In 1998, Steve Fossett set the overall Chicago to Mackinac Race record of 18 hours, 50 minutes (333 miles) in the 60 foot catamaran Stars and Stripes, designed by Gino Morrelli, Bruce Nelson, Britton Chance and Bernard Nivelt.
Emails to the Multihull Mail List from Rob Denney Jul 1999 thru Jul 2002
NOTE 1: The MhMl Archives at steamradio.com appear to be incomplete prior to Dec 9, 2000. The 199 emails on this page are from my personal archives, consisting of Thunderbird folders, dating back to when I (Joseph Oster) joined MhMl on Feb 24, 1996; at that time, the list was hosted at ronin.com. These emails were selected using a search criteria of "from contains denney". It would be nice, of course, to have the full archive restored in a format more accessible than this, but that is a big project for another day.
NOTE 2: 1st HarryProa web page - 1st "U" web page
Subject: [MHml] fastest boat on the water?? From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Fri, 9 Jul 1999 07:12:26 -0400 To: multihulls_at_steamradio.com John, I have just finished building a 40' Pacific proa (named Harry) which _potentially_ fits most of your criteria. 1) Faster than any production boat. As it is not launched yet (waiting for sails and tramp, should be sometime next week), this is unproven. However, it weighs about 1,000 lbs (this is the weight of the components, I will weigh the lot on launching day) and will have 750sq' of sail (power to weight ratio higher than Playstation and Stars and Stripes, I think) so it should get along fairly quickly. The rig is only half size at the moment until I know it works. The doubling is easily achieved using a telescopic mast. The rigs are semi rigid wings, with the mast enclosed. This means the masts can be very large section, light, strong and cheap. It also means the centre of effort of the full size rig is only 16' off the water making for ample stability. 2) Build it myself for less than $30,000. Harry has cost $US4,000, plus maybe another $500 worth of stuff I had floating around. It is cored construction (flexiply with glass both sides) and the only carbon is in the rudder shafts. Time is 15 weeks from start to now. The cost and timing blew out because I built 2 wing masts which I then scrapped as they were too cumbersome. There was also a lot of thinking and experimenting time. The 2 hulls, beams and stub masts were built to undercoat stage in 160 hours. Because it was built under my house, where space is limited, a lot of time was spent waiting for glue to cure. The next one would be sailing in under 2 months. For $30,000, you could use carbon in the rigs and save a couple of hundred pounds. Or build a 60 footer which would weigh less than a ton and have well over 1,000 sq ' of sail. An all carbon version would weigh half as much, and cost maybe 3 times as much for materials, plus moulds, vac bag etc. Harry is a schooner, for cruising related reasons. A single rig would lower the weight (and the cost) and increase the light air speed. Harry is engineered on the "looks right, hopefully it is, but even if it's not I am the one who has to fix it" system. Before building a race version, I would run some numbers past an engineer. 3) 4 Single births (almost nothing else inside the bare hulls) Harry will eventually have 2 double berths, toilet, nav station, galley etc. This will add about another 250 pounds (in the right place, to windward). For racing, the 4 single berths, and not much else, could be fitted into the 24' long windward hull that I have. I will be building a racing weather hull once everything else is finished. Swapping them over will take about 5 minutes. 4) Everything including sails made myself I made everything on Harry. Purchased materials were the core, bits of framing timber from the local hardware, reinforcement, resin and additives, wing covering (this was sewn by Gary Martin, a very understanding of weird requirements sailmaker, but as it requires no seam or luff shaping, this could be done by you), spectra string (75' of 1/4", a roll of 1/12" and miscellaneous bits of in between sizes), house paint (Harry has a 20' paint job, except below the water which is copper filled epoxy and will be 1200 grit w&d. A showroom topside finish would add a couple of grand), and 20 x $1.50 pulleys to control the wing shape. Tools are 4" and 9" grinders, saber saw, drill, orbital sander, router if you have one. Consumables: self tapping screws, a couple of sheets of chip board and 10 yards of sandpaper. Apart from the pulley axles, and the sail eyelets, there is no metal on the boat. 5) Outboard motor power (price of outboard not included) I expect 3-5 hp will push Harry at 5-6 knots. I designed and built a 40' cat in New Zealand last year which did 6 knots with 4 hp. Harry is heavier, but has less wetted surface. 6) Trailerable (once a year, price doesn't include the trailer) Harry's main hull is 40' long and weighs 310 lbs, which is trailerable once a year on a flat bed truck. All the other components are shorter and lighter and could be loaded singlehanded. The end 8' of the leeward hull is not loaded by rudders or stays. Making this detachable is on the list of things to do. This would mean the longest component was 24' long, and could maybe be loaded single handed. I have rigged Harry singlehanded and will probably launch it on my own. This involves rolling it across 100 yards of mud flat. 9) Something that could blow away everything in the Chicago-Mac Race (with the right crew). No idea of the competition or the race conditions, but I think you would be in with a chance. The balanced wing rigs should be much easier to trim than soft rigs. There are no winches, tracks or highly loaded sheets or halyards. One single purchase string per wing controls angle of incidence, another controls camber. There are two tillers, one of which is locked, except when you want to climb up to windward. Flying extras is a bit problematic. Hopefully the weight is low enough that they will only be needed in the very light, or not at all. Time will tell. Tacking a Pac proa with balanced rigs and reversible rudders is about as fast as tacking a conventional multi. However, there is a loss of windward position, so you probably want to avoid tacking duels. It is much easier (bear away, dump 2 sheets, pin the tiller, unpin the other one, pull in 2 lightly loaded strings, luff up) though, so you might win a 50 tack duel as the opposition would be knackered, and you would not even be sweating. Harry is the third Pac proa I have designed and built. Some of it is incremental developement. Some of it is first time stuff. There will be teething troubles and breakages. Once (if!) these are sorted out, Harry should be a fast, easily handled, comfortable cruising boat for 2 couples. Regards, Rob
Subject: [MHml] Harry From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sat, 10 Jul 1999 10:11:40 -0400 To: multihulls <multihulls_at_steamradio.com> Thanks for the interest in Harry. Re the Chicago/Mac race, I agree that it would need a special boat to beat S&S and co. I still think it could be done in a Pac proa for less than 30k, but there would be a lot of carbon and no paid labour involved. Even if it couldn't, it would be fun trying. When is this race sailed? Shipping Harry over would cost about $2K each way if anyone is interested............... There are no Harry photos yet. I have always taken lots of construction photos of boats and never looked at them again. This time I didn't bother. When I have some sailing shots they will be in Multihulls Magazine. An article and GA are in an upcoming edition. As for a web page, until Harry is working, I have nothing to put on it, nor time to produce it. John Metza wrote "Some people have told me to procure used parts from a big high tech mono. Boy that sounds like a great idea. When is one of these proa people going to enter a major race and kick some serious bootie? I would love to see it. Have I missed it" High tech monos are built to totally different requirements to fast boats. The first requirement seems to be buckets of money. Using their gear will lead you down the same path. It has been tried many times, notably here with old 18 foot skiff and AC rigs. Cheap initially, but until lots more money is spent, not fast. As far as I know, no Pac proas since Crossbow 1 and Jzero have raced successfully. If there are any others, I would like to hear about them, please. Harry will be competing against the local fleet (no S&S's, but plenty of Farrier type boats and reasonably quick 40 footers) as soon as possible. Gary Lepak asked Q Do I understand correctly that all the accomodation is in the windward 24' hull? A Yes. Lots of people tell me this is wrong, but can't say why. The first purpose of Harry is to determine this. Q Is the rig unstayed? A They each have a spectra stay to the end of the beams, but should be strong enough to stand unsupported. Q Is it easily reefed? A Telescoping the rigs to 40% of their height should be easy enough. Completely dropping each sail will be easy enough. Intermediate reefing is easy in theory, but I have yet to apply the ideas in practise. It is possible with the wing rigs that intermediate reefs will not be necessary. Q What is the construction of the akas? A I have a thing about jargon. Except for copies of ancient polynesian proas, let's call them beams. They are bent 5 mm flexiply (3 ply with the outer, lengthwise veneers comprising 95% of the total. Bends to a 4" radius, then glass one side and it holds it's shape. Bloody marvellous stuff, $40 per sheet) with triax inside and out. Q What is the overall beam? A 21', although when the accomadation is complete it will be about 24'. Q Are the berths in the hull(s) or in an overhang? A The berths are cantilevered inboard. Access is from the weather hull. Between the bunks is a walkway between the hulls, with seats on either side and a removable table in between, and maybe a bimini over. The plan is that my wife and her friends can sit here drinking wine and chatting, completely seperate from the racing/sailing aspects. The seats and cantilever are each one piece, flexiply/glass. Q At under $5k, and 4 months building time, I'd say that you have a cheap, comfortable, AND fast boat, which isn't supposed to be possible! Of course folks have different ideas of what "comfort" means. What type of cruising would Harry be capable of? What payload could he carry? A Cheap, comfortable and fast aren't possible in a conventional boat. They are in a Pac proa, but at some cost in terms of quick tacking and gybing. More importantly from the perspective of popularity, at huge cost in conventionality. They are where cats and tris were 30 years ago, and I suspect people are even more conservative now than then. Evidence of this is that there are only a few of Russ Brown's beautiful boats sailing. Incidentally, the comfort is not there yet. This will take another month (less if I slip Harry to do it) and probably another $1,000. Comfort is 1.9m (6'4") headroom in an 800mm (31") wide hull, 2 x 1.3m (4'3") wide x 2m (6'8") long double bunks with sitting headroom, enclosed toilet, seperate shower, large galley and nav station (cantilevered 2' out on the outboard side), table and seating. More importantly, it is being able to seperate the sailing and socializing functions of the boat. Hopefully the seating area will be free of spray, while still offering 360 degree views. Harry is for 2 couples for a weekend, and spartan racing for 1 or 2 for longer than this. Extended cruising requires more payload/bigger hulls which would reduce performance, or longer hulls. Cruising displacement is 1100 kgs. No big deal structurally if this is exceeded somewhat, but performance will go down. Q Last question: Where do you sail and when is launch day? A Brisbane, Australia. When it is ready, maybe this week, and sailing next weekend. Anyone visiting this neck of the woods is welcome to come for a sail once it is working. Bob Hobbs wrote Being a wingsail designer myself, I am very curious about your wing. Anything you can tell me ? Sure, anything at all. However, no one I explain it to understands what I am talking about! It is nothing special, all ply, pine and pulleys. Basically a NACA 0012 foil with solid, removable nose pieces and the trailing two thirds of each side able to move relative to each other to create camber. A vertical batten inside the wing supports the leech. The mast is at 25% of the chord to reduce sheet loads, the nose supports the luff and eliminates halyards. No idea of the loads it will see, so I expect some breakages, but there is nothing in it that a bit of uni glass won't fix. I will be amazed if it all works first time, but the theory is pretty simple, so eventually it will. regards, Rob
Subject: [MHml] Flexiply From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Thu, 15 Jul 1999 03:50:57 -0400 To: multihulls list <multihulls_at_steamradio.com> Michael Rowe wrote "The construction industry in our area calls this "wiggle board." ......... " The Flexiply used in Harry is not Luan, but a fairly coarse grained (which makes it easily bent across the grain), pale timber the same weight as gaboon. It uses a water and boil proof phenolic glue, and apart from an affinity for mould, and probably for rot, if it is not epoxied, is eminently suitable for marine use. Anyone seriously interested in importing it to the USA should give me a call. Regards, Rob
Subject: [MHml] Pacific Proas From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sat, 24 Jul 1999 02:06:17 -0400 To: multihulls list <multihulls_at_steamradio.com> Craig O'Donnell said: The fact is that the Pacific Islanders design extremely conservatively, within the proa envelope. Craig implies that modern Pacific proas are the same as the proas of the Pacific Islanders. This is incorrect, and as Pacific proas are on the verge of doing to the sailing scene what catamarans did 30-40 years ago (that is, revolutionise it), it is time for some differentiation. I suggest that the term Pacific proa cover all rig to leeward proas and that the ancient proas, and their modern copies, be given some appropriate Pacific Island name. This could be in the same vein as amas, akas, vakas etc. Perhaps modern proas and multis generally could then revert to non jargon descriptions of these such as beams, windward hulls and leeward hulls. Craig also said: THEIR boats aren't 'radical' any more than a Baidarka of seal skin is 'radical'. Lack of radicality is a hallmark of traditional boats, or so called 'artisanal fishing craft' -- home made traditional boats -- worldwide. I think he will find that given the restraints of materials and boat usage, the Pacific Islanders designs were pushed as far as they could go. I am not sure anyone could do much better today, given those restraints. I bet the first person to suggest that sailing outriggers could go in both directions and thus become proas was considered a radical, as was the wise man who originally suggested using seal skins instead of whatever they replaced. If these craft are now non radical it is a function of evolution, not any lack of radicalism on the part of their owners. The same applies to modern multis. 40 years ago they were radical, now they are well within the envelope. Regards, Rob PS Harry is launched (leeward hull draws about 3") and trials will begin as soon as the rain stops.
Subject: [MHml] twin una rigs From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sat, 24 Jul 1999 02:06:21 -0400 To: multihulls list <multihulls_at_steamradio.com> John Metza says: With the exception of Bob at DynaWing....... snip......Would anyone designing a catamaran for a customer recommend one of these rigs? Discourage it? What advice would you give? John, Bob said it all, what else would you like to know? There is no reason not to have twin rigs except that they are different, so obviously no conservative, correct thinking yachtsman will consider them until/unless Goss wins The Race. My comments as an occasional designer are: Unless you have shares in a fittings company, and enjoy hard work while you are sailing, (Don't laugh. All the evidence is that this is what the vast majority of multi and mono owners want) I would not recommend the twin una rig any more than I would recommend a conventional sloop rig. If keeping the centre of effort of a large sail area low is a priority, I would suggest a balanced rig in each hull, similar to what Pete Goss originally specified. (Incidentally, did anyone ever come up with a sensible reason why the aerorigs were not used?). The best option, in my opinion, is a single, unstayed, balanced rig, located in one hull. We tried this on W (40' cat) last year, and the limited testing that has been done to date, shows no ill affects. It certainly puts to rest all the unbalanced driving forces criticisms. It is also an incredibly low cost (both to build and to maintain) method of achieving the design criteria for this boat. Of course, such a rig looks different, so no one will ever regard it as anything other than a freak, much less buy it. regards, Rob
Subject: [MHml] Carbospars From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Mon, 26 Jul 1999 18:15:46 -0400 To: multihulls list <multihulls_at_steamradio.com> Gary's comments on Carbospars are a bit harsh, and while they may explain why Goss is not getting them to build his rigs, they don't explain why he has gone for the una rigs over the Aerorig, or a copy of it. . "Things may have changed but the Aerorig certainly used to be constructed spiral wound on a mandrel. Various word of mouth (and therefore I must stress unlreliable) reports indicate that there is quite a lot of unnescessary weight due to suboptimal resin / matrix ratios." Aerorigs now have wing section masts, a shape which is easier to female mould than to spirally wind. Spiral winding, done correctly, provides resin fibre ratios which are only exceeded by high pressure female moulding. However, on small masts, there is frequently more off axis reinforcement than is necessary. This should not be the case with large masts. "Carbospars also used to (and may well still) guarantee their spars for life. Ergo quite a lot of _extra_ engineering. Not always the best way to go." This is a function of what Carbospars thinks Aerorig owners want. It does not mean they are incapable of building to a tighter spec. The life garantee should not add much weight/structure/engineering. Unlike conventional rigs, an unstayed carbon mast, particularly with a balanced rig which applies lower crash loads when jibing, does not need much built in redundancy. Carbon epoxy has exceptional fatigue properties, so as long as it is initially strong enough and built properly, there is not a lot to break. Carbospars have a reputation for being expensive." No arguments here. A well earned reputation! However, they have done a lot of developement work, which someone has to pay for. "The biggest Aerorig to date has been on a 100 footish mono. Nowhere near the height Mr Goss is talking about. I wonder if it would even fit in their factory." Carbospars built a J class (Velsheda??) mast, the longest in the world so far. Suspect shed space would not be an issue. "Personally I reckon he will end up with a pretty neat rig which may well change people's buying habits." No argument here either. However, a neat rig for a balls to the wall racer easily capable of exceeding wind speed is not a neat rig for the average cruiser and most racers. For them an Aerorig is far more suitable. Yet another instance of cruisers being duped into buying racing technology. "No offense to the guys from M&M but I'd rather see Pete Goss win than Steve Fossett. I guess its the famed Oz desire to back the underdog coupled with a desire to see something "new" in the technology stakes rather than "more of the same" (even though the engineering problems with Playstation are totally leading edge)." Me too. I have no connection to Carbospars, other than having quoted against them a few times. I do admire any company which tries to sell a new, easier to use rig. Needless to say, I also think Aerorigs/ballestron rigs are way ahead of anything else available. regards, Rob.
Subject: [MHml] twin una rigs From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Tue, 27 Jul 1999 09:35:31 -0400 To: multihulls list <multihulls_at_steamradio.com> John Metza says "This fall/winter I will retrofit my 5.0M G-Cat with Twin Una-rigs consisting of Twin DynaWings. " <You Beauty!!! Wonderful to see the talk stopping and the action starting. Seldom seen with innovative boats these days. "The rigs will be built with a tilting mechanism .." Be very careful about adding weight. A 16' cat's performance will diminish very quickly if it is overloaded. If the tilt mechanism weighs more than a few pounds, leave it off or you will end up disappointed and may not proceed. Make sure you weigh it in it's normal state before you burn the bits and try very hard not to exceed this weight. Also get a gps and do some accurate speed and tacking/gybing angle runs so you are comparing apples and apples. Or find another G cat and sail side by side, before and after. "I am going to extend the beam of the G-Cat from 8 to 16 feet. Without the loading on the central beam I anticipate no problems in the structure even with this added beam." "I suggest you do some calcs on this (let me know some weights and beam dimensions and I will look at it if you like) as the loads are pretty different. The mast in the middle/dolphin striker set up loads the beam in compression, one in each hull loads it in bending. "The increased beam will of course allow me to carry more sail area with fits into my long term plan for the boat to kill Stars and Stripes". Maybe. Most overcanvassed cats capsize diagonally, not sideways. Length (or as a lousy second choice, full bows) are the cure, not more width. Still, you will find out the optimum ratio pretty quickly, and have a lot of fun doing it. "Here is my plan for the S&S Killer: I will procure used, or build a pair of Formula 40 hulls. Check the rules to see what space is required in the hulls. If this is available in a F40, and you can find one cheap enough, go for it. If not, it will probably be cheaper/easier to strip plank a hull. 10mm cedar with 6ounce uni glass each side, hulls as rounded as possible would be hard to beat cost wise, and probably quicker to build than to extend a F 40. "I am going to look into the cost of extending them to as long as possible. There must be a point where the costs of the structure get excessive, maybe someone out there can help me out with that?" Depends largely on the rig. If you have forestays attached to the bows, the loads and stiffness required are pretty high. If the rigs are freestanding, the loads are localised, and the only loads on the bows are the water loads, both vertically and when hull flying, horizontally. These are not trivial but mean a much longer boat is possible. Cost of length is pretty cheap. Cost of hull height and width is less so, as bulkheads etc are needed for the larger panels. Cost of overall beam and strength tends to be very high. Keep it skinny, low and lightly loaded. (Use S&S as a guide, but round the gunwhales and decks as per Goss' boat. "The formula 40 hulls will be spread much farther apart than a typical formula 40's 24 feet. I am looking at basically as close to a square boat as possible. " The other big problem with square is tacking. Fingers Crossed with it's humungous rig and 24' (?) beam found it easier to gybe, which makes the whole upwind exercise pretty pointless. Lots of rocker helps, but is slow. It may be faster to fly a hull than to carry lots of rag. Righting moment is not the whole story. "The beam structure, since it is supporting no rig can be made much lighter/wider. I would like to know people's feelings on giant foam/epoxy wings for the beams (to lessen aerodynamic drag). " Big is definitely better, structurally, but keeping it light and streamlined may be a challenge. Calculating the optimum size is not too difficult. Start looking for cheap carbon. For light structures in bending it can't be beaten. A thin faired beam will have less drag than a thick faired beam. "I will of course be looking for used parts from all sorts of sources for the beams and anything else." Cheap is good, but light is better. The rig will be (provided they live up to my high expectations) Twin Una-DynaWings. <I'm betting they will easily live up to your expectations. But again, watch the weight. "I will have more sail area than S&S, with a lower CE and larger beam which will allow me go faster. My boat may be a little shorter, but I will overcome that with the power of the twin rigs. Should the conditions arise, I will be able to push the boat much harder with much less fear of capsize that S&S has." Make it as long as practical (trailing, mooring, etc). Then nominate a wind speed (check the race conditions over the years) at which you want to fly a hull, and adjust the beam accordingly. I suspect it is not fear of capsize that limits S&S, more fear of breaking. "I think when I build the rigs, I will test the boat with only one rig. Maybe that is how I will handle reefing? Just leave one rig off!!! What do you think?" No reason why not. I suspect that the little boat will perform better with one rig as the weight and complexity will be less. While I think it is wonderful that you are experimenting, I think you will find the following: For $30,000 you will not get a conventional (apart from the rigs) cat lighter than S&S. A cheap 40 x 40 footer weighing less than 2.5 tons will be a challenge. Longer will be heavier. You will have a boat which, if it stays together, may beat S&S in a gale, but otherwise won't. The cheap way to beat huge, powerful boats is not to try and go bigger and more powerful, but to rotate the spiral in the other direction. Go lighter, with less sail, lower, localised loads, and fewer gadgets. Start from the lwindsurfer end of things, not the Playstration end. What I would suggest is that you do a spread sheet (or just a list) of all the component parts and their weights (and costs if you want to get depressed). Then go through and eliminate half the rudders and centreboards, half the rigs, half the fittings, half the beams and 3/4 of one of the hulls. You will then have a boat with superior power to weight and power to wetted surface ratios. You will also have much better diagonal stability and a much lighter loaded craft. In fact, you will have a pac proa. Tacking will still be slow, but at least you will be able to do it by sailing across the wind (shunting) rather than having to sail downwind.(gybing). You will also have a boat which will have some potential for cruising between whipping S&S each year. Regards, Rob
Subject: [MHml] jargon From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Tue, 27 Jul 1999 09:45:26 -0400 To: multihulls list <multihulls_at_steamradio.com> Still raining or else I would let this pass. Anyone not interested in Rob and Dave splitting hairs (again) should move right along. Dave Culp says "It's tough enough to speak distinctly about proa parts. Using "generic" terms such as "windward hull" immediately begs the question, "Would that be an "Atlantic" windward hull or a "Pacific" windward hull?" You pick what you want to call it, but several thousand sailors understand immediately what you mean when you say "ama."" snip "As to "jargon," Rob, aren't terms like "windward" and "leeward" jargon themselves? (Just ask any auto mechanic...) The windward hull of an Atlantic proa, a Pacific Proa a cat or a tri are just that: The windward hull. Several thousand might understand, several million wouldn't have a clue, yet would understand immediately what a windward hull or a beam (even your auto mechanic would understand this) is. Ama, aka and vaka seem to be popular in the USA but are unknown in Australia, New Zealand, and I suspect Europe, except by Newick fans and admirers, of whom incidentally, I number myself. Explain what they are to anyone who doesn't already know, and they will respond: "why not call them beams, windward and leeward hull?" Dave "I say, use the term(s) you're comfortable with, but perhaps it's a good idea to learn to "understand the language" of the culture you choose to belong to?" If by the culture I choose to belong to, you mean American multihullers, I consider it enough of a concession to use unnecessarily complicated weights and measures without also having to use unnecessarily complicated descriptive terms. If you mean the ancient polynesian culture, I don't consider that the pac proas which will become popular have much in common with these boats. This is not denigrating the polynesians. But, as Craig pointed out, they are optimised for fishing and working in warm water with a crew of many, not weekend cruising/racing with the wife and kids. They are also built from materials which no one in their right mind would use today. Regards, rob
Subject: [MHml] jargon From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 28 Jul 1999 04:17:29 -0400 To: multihulls list <multihulls_at_steamradio.com> John Dalziel said "Now, for proas it seems reasonable to differentiate, and name, based on the intended function of the floaty thingie that mostly stays to windward (or leeward as the case might be). So as a name, "windward hull" is pretty much out, and something better might be: log, ama, hama, float," John's argument for specialized terms is a good one. However, when describing proas to laymen (almost everybody), I find it easier to use the language we all speak. On the rare occasion that what was the windward hull becomes the leeward hull, it is easier to explain this particular circumstance than to try and invent a whole new language. Those who understand akas, amas, etc will have no trouble comprehending being caught aback. It has stopped raining, I'm going sailing. Actually, I will mostly be motoring, stuffing around, stuffing up, enjoying the scenery, passing anyone I can, avoiding anyone I can't and sitting on the hook drinking tea and waiting for the tide to come in. Perhaps someone could dig up some ancient polynesian terms so that we can distinguish between the name of what I am doing and it's description. This way, only those in the language loop will realise what we are doing and we can keep the knowledge to ourselves. This is the point I am trying to make. regards, Rob
Subject: [MHml] Carbon spars From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 28 Jul 1999 04:17:34 -0400 To: multihulls list <multihulls_at_steamradio.com> Pete McDowell asks "Are you in the business of designing/marketing (maybe even making) carbon structures ? I'm thinking of things like rigs, beams for multis, etc, here." I used to make carbon spars, foils etc, then got diverted making fittings (winch handles, blocks, furling spars etc), but back burnered this as venture capital proved difficult to find. I now design, and if required, build boats for people who want something different, preferably lighter, faster, easier to build or cheaper than what is currently available. During the spar making stage, we came up with some very effective tooling and processing options. I now make these available on a consultancy basis. I will be in the USA in September setting up a carbon mast/beam factory as part of this. Incidentally, if there is anything interesting happening on the Eastern seaboard of the USA at this time, I would like to attend. Last year I designed and built a 40' cat in NZ (named W, see next Multihulls mag, or Inside Multihulls web page, eventually). An upshot of this was the guys whose shed I hired got interested in carbon and acquired 2 autoclaves, one 3' cubed, the other 60' long x 2' diameter. They are currently rebuilding Playstation and doing the deck for the kiwi AC boat, but when this is finished, they will be available for carbon work. I also have an arrangement with a very competent builder here in Aus. I employ an engineer when required, plus I have a smattering (enough to be dangerous!) of expertise. Sorry for the ramble. The answer is yes, I can probably help with your masts and beams. Regards, Rob
Subject: [MHml] proa design question From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Fri, 13 Aug 1999 08:13:44 -0400 To: multihulls list <multihulls_at_steamradio.com> Jeff Gibert asks why a proa cannot be tacked. They can, easily. W is a 12m cat in NZ with the rig and foils mounted in the port hull. The rig is an unstayed ballestron. W occasionally gets caught in irons tacking from port to starboard, due to the rudder being on the inside of the turn. Starboard to port is no problem. Pictures and an article on W are on the Inside Multihulls web page, or will be when Terry puts it there. The question should be not whether it is possible, but why bother, particularly with a conventional stayed rig which requires significant beam on either side of the mast for shrouds and headsail tracks? An Atlantic proa will actually perform better (up to slightly more than hull flying conditions) as a cat than as a proa, assuming it is set up accordingly. A Pacific proa that does not have to tack can be far lighter than a cat or an Atlantic proa, with lower and more localised loads, meaning there is much less to go wrong. Shunting is less effective in terms of vmg to windward than tacking, although with a balanced rig, shunting time is close to that of a conventionally rigged cat. Short handed, the difference diminishes. Shunting is also much more controllable, as speed is not a requirement, although room to leeward most certainly is. The proof of the above is that rarity according to recent postings, a 12m Pac proa with wing rigs which is more than just a sketch and a discussion. Harry is now in the water. If you are ever in Brisbane, let me know and come for a sail. For those who are interested, the non rig bits of Harry are complete and initial tests show that the rockerless hulls with twin rudders are easily maneuverable. Harry turns 180 degrees in either direction in 2 boatlengths with one rudder, less with both. A 5 hp outboard at 3/4 revs propelled it at about 7 knots (timed due to no show of friend with gps). More accurate numbers, including drag details are planned for the near future. Weighing pre launch did not happen, but according to the waterlines and Maxsurf, 400 kgs (900 lbs) is pretty close. I am currently adding another 100 kgs (220 lbs) of accomadation to the windward hull to make it habitable, with 2 double bunks, galley, headroom etc. Cost so far, $6,000 ($US4,000), excluding mistakes and design changes. Time: 5 pretty relaxed months which include a heap of thinking time and changes. The wing rigs are not working. Lots of teething troubles, but all surmountable, I think. Halyards have been eliminated and sheet loads reduced to a single purchase, but the vertical battens (sail plan form is rectangular) and uncomplicated control system are taxing my ingenuity and patience. Regards, Rob
Subject: [MHml] Re lifting a hull From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 18 Aug 1999 17:41:23 -0400 To: multihulls list <multihulls_at_steamradio.com> Obviously going without, slipping or working between tides are options. Inflating 44 gallon drums would be difficult. Each 44 gals (200 litres) will support 440 lbs (200 kgs) so you will need 13 to lift half the 5 ton boat. Done carefully, I see no reason why careening would be a drama. In fact, I think it would be fun and the experience may even come in handy down the track. I would not use the main halyard. It is probably not strong enough, and the lead from the sheave is awful. Tie a loop (2 or 3 turns will ease the load on the knot which should be a bowline or a clove hitch around the standing part for spectra/kevlar) around the mast under the cap shrouds and with a seperate piece of rope tie the loop so it cannot slip down away from the caps. The looped rope should have a breaking strain of at least the boats weight. 12mm spectra is 6 tons. The pulleys should have similar breaking strains. I doubt your winches will pull these loads, so use a multiple purchase. The turning blocks on the mast are probably dubious as well. Probably better to use a come along or a chain hoist attached to the pulling point on land The fenders should be as big and numerous as possible and placed near bulkheads/frames/stringers in the hull. The jetty edge should be as low as possible. Watch the fenders as the loads come on to ensure they are not flattened, and the hull is not flexing or cracking. Watch the mast to ensure it stays straight, watch the rope for signs of fraying and the pulleys for nasty cracking noises. The hauling rope should go to as high a point as possible to reduce the angle. Failing this, it should be as far away as practicable. If you work from inside the hull, there will be no danger, nor need to lift it more than just clear of the water. Use a hot air gun to gently warm and dry the substrate before epoxying it. Fast hardener, left in the pot until it starts to warm up will speed things along. Lower the boat as carefully as you lift it. Do it when there are as few people around as possible. I usually do tricks like this as soon as it gets light in the morning. Fewer busy bodies, fewer boat wakes and calmer weather. Have fun Rob
Subject: [MHml] This DynaWing Thing From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Thu, 19 Aug 1999 17:32:50 -0400 To: multihulls list <multihulls_at_steamradio.com> Also of interest, National Geographic a few years back ran an article on an > >Irish character (gypsy horse showman I think) who built a canvas/tar covered > >catamaran (30ish feet) to sail the Atlantic that featured an interesting rig. > >It was junk like, having a series of flexible timber battens (like sections > >thru a syn wing) that had a nose piece, a mast hole, and then trailing faces. > >The battens tapered from bottom to top - ie all similar shape, but bottom > >biggest, top much smaller. These were covered with poly tarp cloth, and from > >memory the pictures looked like a sym wing when sail hoisted but head to wind, > >but of course on sheeting in, sail altered shape to an assym wing. Looked > >really interesting - balanced, easily reefed, low loads everwhere, no winches This sounds like a description of one of Rob Denney's rigs. Rob? The article I saw was in a Wooden Boat publication. An interesting boat, built by interesting people, but very little worthwhile info on the rig, which they call a tuna rig. The article was about Mark 1, and closed by saying they were building Mark 4 for a client in America. Mark1 got them from England to the Caribbean on a boat which was definitely not race oriented, so it must have worked. The boat was actually pretty tricky. Tar and canvas over frames. Nearly bullet proof, apparently and very cheap. The builder was a craftsman par excellence, judging by the photos. The wing rig I built for U (23' Pac proa) was similar, as far as I can tell. The problem was keeping the sail cloth taut around the front of the wing without large halyard loads. Not a problem for a slow tradewinds rig, but not very quick. The rig for Harry is an improvement (that should read "I hope the rig for Harry...") . Differences are a multipart flexiply removable leading edge, a rectangular plan form and no halyards. The battens attach to the mast and angle of attack is controlled by turning the mast which is easy as the rig is balanced. The windward and leeward battens are controlled with strings to induce camber. Loads for this are also quite low, about 2 kgs (4.5 lbs) per batten. Automatic camber change when shunting. Pretty simple, but not yet working, due to teething troubles, although I had no trouble with models. As soon as it is working (2 weeks, the same as for the last 3 months), photos and drawings will be available. Some customers (from my epoxy selling days) of mine built a Tuna rig for a 40' steel mono a couple of years back. I never saw it, but they are now cruising the Southern Ocean and according to reports, it works well. Again, slow and cruisy. If anyone wants a copy of the article, try Wooden Boat. I lent mine to a friend, who lent it to someone else. It may take a while to track down. Rick Anderson asked Now to start the flames and knives - how'd that go as a "poor mans" Ballestrom for a Proa? You don't get much poorer (well, tighter arsed, anyway) than me, Rick. Hopefully it will go well. It also costs peanuts. About $AUS1,500 ($1,000) for the masts, battens and sails (made by Gary Martin, but as there is no shape, a decent home sewing machine would suffice) for 2 x 16 sq m rigs. Apart from a dozen $US1.50 pulleys and a roll of 2 mm spectra string, there are no shop bought fittings. Eventually, they will be 2 x 32 sq m using telescoping masts which are relatively easy when the masts are inside the sails and there are no halyard loads. Could be cheaper using lighter sail cloth and bigger section masts. Ideal for a proa as the sheet loads are low. This reduces the string required from a multiple purchase system when shunting. Note that this is not a proa specific rig. Anyone wanting low cost, low load, efficient rigs will benefit if it works. Regards, Rob
Subject: [MHml] Harry From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 25 Aug 1999 04:20:46 -0400 To: multihulls list <multihulls_at_steamradio.com> Robert DesRoche (and others), Many thanks for the enthusiasm, but let's not get too excited just yet. Harry is nearly complete (if it would only stop raining), but has yet to prove anything except that it is light, roomy, easily and cheaply built and easily driven. Until it is sailing, you should keep your backyard as it is! There will be some pictures in the next day or so on the U web site which show what happenened when enthusiasm got the better of detailed analysis. There is also a bit more on this site than was in the Multihulls article. I will post progress reports as they happen, but I owe the MM crew for a lot of favours and information over the years, so full details will appear there first. To those interested in Harry plans, the answer is not until it is working satisfactorily, and has done some offshore miles in rough conditions, maybe by the end of the year. Then I will sell a kit containing all the materials required to build the boat (including the rigs) to sailing stage, plus detailed instructions/drawings on how to do it. The kit will cost about $US10,000. Yeah, I know it's a lot of brass for a 40 foot cruising boat, but I need to earn $30k to build a 200 kg (440 lbs) Stars and Stripes beater! Regards, Rob
Subject: [MHml] Beam lashing From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Thu, 26 Aug 1999 17:45:26 -0400 To: multihulls list <multihulls_at_steamradio.com> Robert DesRoche asks Who knows of a fast and cheap way to attach crossbeams on a demountable cat or proa. webbing straps or lashing ala Tiki, nuts and bolts, tow balls and couplers ( that is my idea, cheap and fast and pretty darnd strong.) I want to make a trailerable proa and can't seem to fit it into the trailering envelope. The fastest and neatest is tapered beam ends and sockets. Use large tapers, in both horizontal and vertical planes. Strong, rigid and easy to assemble/disassemble. Hold them in with rigging loads or a dowel. Cheapest is vb cord (3 mm1/8" terylene lashing) wrapped around a wooden block glued onto the topsides. The beam needs to be supported as far apart as possible to reduce wracking loads. Sitting the beams in slots cut in the gunwhales works well. Webbing straps are more expensive, difficult to tighten and need thicker blocks than vb cord. A ball and socket is great if you want multiple degrees of freedom, but heavy. Like nuts and bolts they need to have the load spread fairly well, both on the beam and the deck. Strength is not a big problem for Pac proa beam attachments, assuming a shroud to windward. The loads the beam attachments see are not much more than 150% the weight of the crew plus the float, maybe doubled to account for wracking, waves etc, then divided by the number of tie downs, bolts etc. Regards, Rob
Subject: [MHml] Harry vs tradition From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Fri, 27 Aug 1999 03:50:13 -0400 To: multihulls list <multihulls_at_steamradio.com> Tom Eletto asks My question is based on the comments of John Dalziel regarding a loaded windward as opposed to leeward hull. You obviously don't agree with his analysis. Has your experience simply shown you that the problems he details don't occur or ??? I agree with some ofJohn's analysis. Where I differ is the conclusions and the emphasis. Most of my comments are based on experience. Those that aren't are based on common sense. John says The answer in the Pacific has been: a light log with very nearly neutral buoyancy, movable ballast (crew) sent out onto the platform as necessary For me to ask my wife to bring along 6 friends and spend the day running up and down the beam of Harry, occasionally being fully immersed when the breeze died would have killed the project, my marriage and my design credibility stone dead. This comment supplies the brief answer to Tom's question. For anyone who wants the long answer, read on. John says it is comparatively rare for a boat to be sailed at its maximum stability point, and this is the *only* time that the "all weight to windward" is to your advantage. So the rest of the time- which means most upwind travel, but also effectively includes all reaching and running- you are simply adding to your drag by keeping the weight to windward- since you have to keep it from sinking even when it is not needed for stability, you've added skin friction and wave drag. If the max stability point is low then it is quite common to exceed it. The weight is advantageous at all apparent wind speeds over the breeze at the max stability point. With little or no weight to windward, the max stability point will be at low apparent wind. With a lot of weight to windward, the beam, for a given stability can be much less. No doubt that the weight to windward adds friction and wave drag. Against this is the usable space, comfort and dryness that is gained in a relatively short hull. Compare living/sailing in the lee hull of a fast cat with living/sailing in the weather hull of a fast tri for an indication of the difference. The log type boat is for racing, the accom to windward is for fast cruising. John says You have also added structural weight, in spades. Even with the rig on the lee hull, the weight of the windward hull will have the same effect on the structure as it does on an Atlantic proa or catamaran. Though the lee hull is fairly light, it will still have considerable skin friction, even when not pressed, for it must be designed for full immersion and have underbody lines to match. It will also be considerably heavier than a comparable log on an equal-sized Pacific canoe, and will need to be structurally able to resist the strains of the backstay and mast(s). To me, a Pac proa without a balanced, self supporting rig with a stay to the end of the beam is a nonsense. Given this, I cannot see the relevance of the above. John says Motion will be much worse on a boat with a strong windward weight bias, since the heavy windward hull, intercepting every wave and reacting ponderously to it, will always be attempting to pitch the lee bow up or down. Roll in a beam sea will be as bad or worse than a catamaran's. Sail efficiency will be a lot lower as well, as the boat is rolling the sail back and forth through the air with every wave, making trim a sometime thing. It is also impossible as a routine matter to fly the heavy hull for cleaner air flow to the sail and less hydro drag. Once the sails are sufficiently loaded, the motion caused by beam waves is more up and down than rolling. This applies to any boat, but will occur in a lower breeze for a low righting moment boat. The motion with unloaded sails may be worse, I don't know. I personally have no problem with cat motion in a beam sea. I do find the motion of a rowing scull (pretty close to the motion of a hull with a semisubmersible log, I suspect) in a beam sea to be awful. I can't see how flying the weather hull allows better flow to the sails on the lee hull. The overall hydro drag will be the same when either boat flies a hull. The only difference is that it will happen at different apparent winds. Adjusting the beam will make it happen at the ame app wind if this is a requirement. John says You've also added considerable torque against which the rudders must fight. With the sail over the lee hull, and the center of hydrodynamic drag quite a ways to windward near the heavy hull, the sails are acting at a large distance from that drag location. So the rudders must be much larger in order to counteract that- adding drag, complication, and expense. This may well be correct in theory. In practise it is not noticeable. The helm balance of a cat flying a hull barely changes. W works well with only one rudder. It also ignores the large drag from the occasionally fully immersed log, it's supports and it's human ballast, which happens regularly on a cruising boat. John says Another difficulty with the windward-weighted arrangement is that during lulls, the boat will spin sharply to windward due to the drag caused by the heavy hull. This can lead to speed-wasting (and irritating) backwinding. And if you are caught out in heavy weather, the boat can yaw, and the wind forces on the large hull can now drive the boat into a backwind. And once you are backwinded it is much easier to capsize, since your weight bias now works against you.. Sorry, this is bunkum. If the windward hull was a WW 2 landing barge it may happen. With sensible sizes, it doesn't. A balanced rig does not get backwinded. A Harry type pac proa will not capsize to windward. John says Let's take a look at Pacific canoes for a moment- and the first thing we see is that _every_ damn one of them violates the "principle" of keeping the maximum amount of weight to windward! NO Pacific proa has the heavy hull to windward. In fact, the weight of the logs on most of the canoes is almost negligible. WAAN AELON KEIN (in multihulls mag proa issue) is a good example, and typical. In Haddon & Hornell, the largest log I could find, and that on a 45'+ boat, was about 350#. So the "all weight to windward" theory is simply not practiced ANYWHERE in the Pacific. It is in Australia, mate! Believe it or not, boat structures, requirements and design have moved on a bit in the last thousand years. In "Dunnies of the South Pacific", by Crappit and Flush (currently out of print, unfortunately) there is NO mention of inside toilets being used ANYWHERE in the Pacific until recently. This is not a good argument for crapping in the back garden. John says what do you do when beating in high winds; you fall off a bit, don't you? That way the waves don't stop you so much and overall you will make better progress than if you had tried to punch it out on a tight beat. This is the problem with these boats. They don't go to windward. For years, multis have been denigrated for this. Now that we have overcome it, John wants to revert. If you want to reach back and forth across the bay, running in and out along the beam, these boats are a cheapish way of doing so. If you want a cheap, comfortable boat, capable of beating most others on all points of sail, then a Harry type is a better direction to travel. John says But if the boat must be used in all sorts of conditions, it will pay big benefits to come up with a boat that will handle the vast majority of those conditions in a competent way, even at the expense of that last dollop of speed during speed week. This is what the traditional Pacific proa does well, and what a proa with "all weight to windward" does not. More bunkum, for all the reasons stated above. The only thing a traditional type proa does well is reach fast, and it only does this if it is built from lightweight modern materials and is sailed by an athletic crew. This makes it ideal for speed week, as Crossbow I, Slingshot (sort of) Gamma and others have unequivocally proved. Finally, I should like to express my gratitude to John for not using jargon (aka, ama, hapa and vaka). It certainly made it easier to understand. Joseph, I don't suppose the above could go on your proa links page? regards, Rob
Subject: [MHml] S&S beater From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Fri, 27 Aug 1999 03:50:20 -0400 To: multihulls list <multihulls_at_steamradio.com> John Metza asks, of his S&S beater: Could Rob Denny Build it? You betcha! As soon as he has sold another 30 harry kits he will be putting his money where his mouth is to prove it. Joseph Oster says ABSOLUTELY NOT... snip.... to be realistic, one must look at the costs of professional construction, engineering, high performance sails and hardware. Joseph's numbers are undoubtedly correct for conventional multis and cruising proas. However, the scaling effects are just not relevant for a go fast Pac Proa. As for his realism, I heartily disagree. Not that it would not be nice, but sucking it and seeing will be much more fun. The 100' leeward hull length is not a particularly relevant part of Pac proa costing. I would start with the race accomadation/safety requirements, the required Bruce number (say 3+, given that S&S with crew is 2.76) and the breeze at which you want to fly a hull (say the average race breeze). The weather hull is the minimum possible to support the safety requirements and the crew and provides the righting moment mass. Within limits, this is the same for a 40' proa or a 140' proa. Calculate the beam from the Bruce # and the hull lift breeze, then work backward to establish what it will all weigh. Adjust the sail area and beam accordingly and most of the work is done! The leeward hull is as long as feasible, taking into account strength vs theweight gain for each additional metre, building shed and trailer size. I will be building a narrower leeward hulled, single beam, single wing, miniscule weather hull carbon version of harry. This would be 200 kgs(440 lbs) (easily, based on what I have learnt from harry) plus crew and would match John's original trailerable requirement. I expect the lee hull of this to be between 40 and 50' long, depending on the finished weight . The big killer in all this, as Joseph points out, is the rig. It would have to be a self made wing, not relying on highly stressed, accurately cut, infinitely tweaked, stretch free materials requiring winches, ball bearing blocks and ball breaking loads to operate. This eliminates a soft sail, and probably a Dynawing as well, unlesss Bob could be talked into doing it for cheap, which would certainly silence his critics. No idea whether my current wing will work, but I am pretty sure one of it's descendants will. John Metza says (of me) You are certainly a skilled craftsman. Thanks, but unfortunately not. What is required for this sort of boat is thinking outside the square. The actual implementation is not terribly interesting and I try to rush through it as quickly as possible, when it is not raining, as it has been all this week. What the job looks like is a distant second to how it works. John asks Could it be built with foam and epoxy or is that too big for such a structure? What would it cost? Bigger boats than this have been built from foam. The cost is dependant on the parameters. Decide these, and convince me (easy) and my engineer (not so easy) that you are serious and we will do some detailed numbers. Then you can get some prices, organise a shed and get started. Allow about 2 man months to build it, but as much as another 2 to get the bugs out. This is another reason for going for the light, small rig end of the spectrum. regards, Rob
Subject: [MHml] S&S killer From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sat, 28 Aug 1999 09:09:32 -0400 To: multihulls list <multihulls_at_steamradio.com> Len Susman says The question here realy is have multihulls and proas specifically reached a level of development where only small gains via tremendous sophistication are possible. If so then the Backyard Builder being capable of producing a serious competitive vessel is gone and the competition has gone to the engineering and construction professionals with the big bucks and high tech access to materials and facilities. And Joe's estimates are right. If the field is still open to development then John and Rob have a window of opportunity, but I think it is safe to say the window is shrinking every day. This is an excellent question. Please read the Harry and U web pages (if Joseph hasn't removed them (grin)) and let us know what you think. I happen to think that _maybe_ the window is still open enough for the backyarder to have a chance. It is certainly open far enough to have a go, don't you reckon?
Subject: [MHml] S&S killer From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sat, 28 Aug 1999 09:09:39 -0400 To: multihulls list <multihulls_at_steamradio.com> Joseph Oster says: I can only go on my own experience hanging around a few multihull projects over the years, usually watching more than working (though I've slathered a good deal of epoxy here and there). I admire you for your web work and am grateful for what you have posted for me, but would respectfully suggest that this lack of design, racing, building and (I suspect), seat of the pants living experience is a poor base from which to comment negatively on Johns boat. Joseph says You really must count labor costs in a project such as this. Bunkum, and Bunkum again! If no one ever does anything new on their own without paying professionals to do it, nothing new will ever get done except by the Fossetts of the world. Get your hands sticky on a project or two for yourself, you will learn heaps about the art of the possible and expand your boating horizons enormously. John has said he will build it himself. Most amateur boats I have been involved with (hundreds, yes hundreds) have been every bit as good as professional jobs, and frequently far better. Joseph Here is another example... snip...Most cats near this size are $200K retail or more Who gives a rats bum? John wants a boat to go fast, period. Looks, standard of finish, building time are all irrelevant. And even if he doen't beat S&S, so what? There is more to life than money. He will have had enormous fun, learnt heaps and certainly won't be last. Bet you any money you like he cleans up your dopey friend in the $140k Farrier tri. Joseph A 100' proa just can't possibly be built for this price or less, IMHO. Money where your mouth is, Joseph. If I build you a 100' proa for $100k, (better than half price, not a bad bargain) will you pay for it? This allows me to employ professional engineers and the guys who rebuilt Playstation to build it, and leaves me enough to build my own S&S beater. What does IMHO mean? Joseph says So are you saying that the front 20 feet (at each end) would not contribute to displacement (only wetted surface area)? Then are you really building a 60' proa with wave piercing extensions at both ends? Hmmmm... What does Hmmm mean? Joseph Proas aren't magic. You still need power if you want to beat S&S. And you need some displacement in that ama for righting moment! For the 21-meter design ..snip. Your design may be fine for what it is, but it bears as much relation to John's proposal as S&S or any of the other boats you have mentioned; that is, none. What have you got against long leeward hulls? Will a 40' proa with lightweight 30' extensions added to each end be quicker? Yes or no. If no, what about 20'?, 10? This is what John proposes and I wholeheartedly endorse. Joseph I've had these big proa dreams for eleven years now... Just trying to be real. And BTW, for Playstation (105'), the construction costs were about $US4.5 million (before the fire) and the operational budget is $US1.5 million per year!! Big deal. How much of that was spent on design, re engineering, changing of minds, fairing, labour, supervisors, phone bills, painting, experimenting, repainting when Sony came aboard, wastage, travel for the Fossett team and designers, consumables for a vac bagged prepreg boat (vast), high temperature moulds, safety precautions, launching, assembly, insurance, transport, Cookson's profit, North's profit, SP's profit, Southern Spar's profit, safety margins at every step of the way, media, launch party, stuff required to race round the world, gear to handle the colossal rig, team uniforms, tender(s), half acre trampoline and it's hundreds of lashings, bank charges, lawyers fees, sails for world girdling, etc etc etc. John needs none of these and very little of the 6 tonnes of carbon in the beast either.. Joseph says Not trying to be a wet blanket here, believe me! maybe not, but God help us and the cause of fast, innovative boats if you ever do! Regards, Rob
Subject: [MHml] Harry vs Traditional proas From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sat, 28 Aug 1999 09:09:49 -0400 To: multihulls list <multihulls_at_steamradio.com> Love the comments, keep 'em coming, please. Linkmeistr asks: that there is a big risk of flying a hull, then dropping it and causing all kinds of directional instability in big seas. I would not want to be riding that animal, but we may get to find out if / when pete goss loses one of his rigs? I may be wrong, only sailing a prao occasionally, but how does the prao inherently stabilize itself downwind? No idea, having not been out in big following seas, but U,W and the 5m all worked well on all points of sail. I would hope that normally it would be the weather hull which flew, in which case it would be no worse than a cat flying a hull. Flying the leeward hull is a scary thought, but no scarier, nor more likely, than doing the same in a cat. A prediction: Goss won't lose a rig. Unstayed masts are so much simpler to engineer, and have so little to go wrong, once they are debugged and tested, it would require a major disaster to break them. Other gear failure, capsize, freeze, fall overboard, maybe, break a mast, no. Joseph Oster wrote No for two reasons: 1) Too much quoting of John Dalziel's article... snip I was asked to compare Harry with Johns ideas. Difficult to do that without quoting him..... Harry is not proof or otherwise of "Norwoods Approach to Pacific proas", whatever this is. I see nothing wrong with adding more stability to large catamarans. I have capsized 2 of them so think it actually has some merit!. The shortness of the windward hull on harry may well be a problem, it certainly is on U. So far, (motoring tests in the middle of the night) it looks OK. If it ain't, I will add another sheet of ply to the middle of the weather hull and lengthen it by 8'. This is one of the advantages of a development boat and a non structural accomadation hull. Please let us know which part of the weight to windward theory you disagree with, and what particular experiences back it up. Hans-Dieter Bader says My proa has the log to windward and I sailed on C...snip.. Therefore to assume that your boat structure is a thousand years superior to something like Waan Aelon Kein is rather funny. Uproariously so, if that was my assumption, but it wasn't. My point is that what I want and what i have available to build it with is different to the Polynesians of 1,000 years ago. I want a fast on all points of sail, comfortable (dry seating, no passenger movement required, full headroom, double bunks etc), cheap cruising boat for weekend sailing. I have no wish to fish the warm lagoons nor do I have a bunch of fit young men to help me sail across oceans, or access to unlimited coconut trees (or whatever they/you build them from) , or the ability to turn such into lovely sleek boats. I have nothing but admiration and respect for these guys, but I reckon that if they wanted to do what i want to do, today, under a house in the suburbs, they would build something much more like Harry than Waan Aelon Kein. Any chance of some performance numbers (preferably comparative with similar size boats) for your boat? And how suitable it is (or could be made to be) for weekend cruising with the wife and kids? John Dalziel says Harry in fact demonstrates one of the biggest drawbacks to Norwood's theory. snip... So you have been unable to attain Norwood's prescription. I wasn't discusing Norwood. I know little or nothing about the man, nor his boats. I was pointing out the flaws in log boats for fast cruising, as requested by Tom. This is the crux of the matter. John says Harry will have no more sail-carrying capacity than a catamaran of the same weight and beam. ..snip.. Harry, as a cat, would be faster than Harry the proa. All else being equal, true, extremely fast. In fact, bunkum. A cat the same weight and accomadation as Harry is impossible, with the materials/technology used. John says Harry as an atlantic proa would be faster than Harry as a Norwood proa, All else being equal, true, extremely fast. In fact, bunkum. An Atlantic proa the same weight and accomadation as harry is impossible, with the materials/technology used. Michael Schact says It's nice to get some experienced proa sailors talking again. Thanks for the nice words. Reality check. I have not done much proa sailing (never more than swimming distance from shore), I have only built 2.95 proas and they are rough prototypes. They are cheap and cheerful because I am. They are very rough by conventional standards (ditto!). Michael asks I wonder if you don't mean comparing a lee cat hull to a center tri hull? Whatever, I was comparing living under a waterfall with living in the dry. Michael asks So for a fast cruising proa such as Harry, would you say that trimaran center hull length:beam ratios are appropriate for the weather hull? My philosophy on all hulls is as long and thin and low as possible, within the major constraints of strength and wetted surface and a bunch of minor ones such as: Harry's windward hull is as long as I could build in one piece under the house. As you say, it will be unloaded most of the time, and when it is not, performance will not be very high on the priority list. Hopefully in these conditions, playing with rig balance, or the oversize rudders will suffice. If the drag is a problem, I will lengthen it. If it is still a problem, I will burn it, chop down a tree for a log, apologise to Sue and the Polynesians and go racing. Michael asks (Or is the secret plan to campaign Harry in a few races when the wife is not aboard?) Cut it out, Sue reads these postings sometimes!!!! So why is the lee hull so long compared to the weather one? I know that longer is better theoretically, but practically speaking, short boats are great for marinas, docking, etc. I would think that a lee hull proportioned like a typical high bouyancy tri float would be adequate. i.e. much closer in length to the weather hull. Perhaps pitch control? You got it. U, despite being a flat bottomed planing lee hull, tended to bury the nose prior to putting on the canted-aft beam. The rectangular wings and schooner rig are also a result of this (lowering the CoE). With a bit (alright, a lot) of imagination, the lee hull looks like two bows of a tri float joined together. There is a plan on the back burner to make the ends removable or inflatable. This would make the longest component on the boat 7m (24'), which would make marinas cheaper (especially if the beams were telescopic or folding, which is pretty easy to do) and trailing viable. Michael says Research done by some people that have built and sailed modern copies of traditional designs (traditional form, modern materials) points to the crab-claw sail (or oceanic lateen) as one reason the heavy windward hull was not needed. ..snip..These researchers of traditional canoe forms state that "sitting out" is hardly needed, and the canoe is much more stable than one would suppose. I sailed a crab claw proa in Kiel, Germany (talk about cold!). The rig (dacron on alloy spars) did not impress me much. Certainly it did not remove the need for weight to windward. When I first read John's praise of them (during Dave Culp's big proa thread), it was too late to try them in harry. However, I did express amazement to him that they appeared to be something for nothing (or not very much, anyway), and asked for details of their speed and windward potential. I also checked out paddle steering in the 5m prototype, and again was not impressed. Just not enough area to reduce leeway upwind. Fine for reaching, and wonderful for paddling out of tight places. John's reply was "One popular notion that I need to spend some time correcting is that the Oceanic canoes are fast for their length when compared to other multis. Not so- they are about the same and possibly a bit slower." At this stage I lost interest in log boats for my purposes. This could explain the lack of need for sitting out with the crab claw. Perhaps it's efficiency is so diminished in a breeze that the heeling force and drive force both drop off? This is much more believable to me than the magic lift from the canted rig theory, which should be easily proved with waterline photos at rest and under sail. It certainly did not happen on the German boat, which I studied closely from ashore and in videos before going for a sail. In fact, I cannot see how a fixed canting rig on the leeward hull can prevent heeling. All it can do is lift the leeward hull. The force trying to lift the weather hull is not diminished. As it heels, the force gets larger as the mast straightens. If anyone can give me provable (numerically, physically or comparatively, ie not gut feelings or wishful thinking) details of crabclaw rigs performance and if those details appear better than Harry's wings (not difficult at the moment!), or the ballestron rig on U or W, then I am still keen to experiment. John and Joseph, in the interests of information disseminating, really should add John's quote to his web essay, along with how well they consider log boats suit the aspirations of 95% (?) of readers of this list for fast cruiser/racers. regards, Rob.
Subject: [MHml] S&S beater From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sat, 28 Aug 1999 18:36:48 -0400 To: multihulls list <multihulls_at_steamradio.com> John Metza asks: I built a proa the same length of S&S out of foam and epoxy. Wouldn't it be lighter than S&S? ..snip.. Now based upon the numbers, don't we now need a much smaller rig to go just as fast S&S? Looking good. In fact it could be less than half the weight, as it would only have one beam, no daggerboards or cases (see below), lighter rig, two crew, not 6, smaller section hull because it is lighter and has less rag. John I build a free standing wing sail (or DynaWing depending on how my testing comes out) with a very large diameter free standing mast inside the wing at maximum chord. Sheet loads greatly reduced because of the mast being so far aft in the wing. Looking better. Extras are a problem, but hopefully only in the very light. A risk worth taking. Why can't the two rudders be transoms hung and kick up like beach cat rudders? Why all the fuss with the spade rudders? 2 large spade rudders remove the weight of the dagger board, case and controls. Spade rudders are very simple to build with carbon shafts. Much cheaper than stainless. Call it Hurry, maybe. Don't let the s grind you down. Regards, Rob
Subject: [MHml] Harry vs log boats From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sat, 28 Aug 1999 18:43:57 -0400 To: multihulls list <multihulls_at_steamradio.com> Craig O'Donnell says Well, Rob, it's really only about 300 years ... but seriously, I don't understand what the argument is here. <Me neither. Craig asks Traditional boats simply did not have a "balancing" (aero, easy, simple, balesto)-rig. So how can you compare two essentially different hull forms along with two essentially different kinds of rig? The same way you compare monos and multis, I guess. Tom asked how my experience/ideas stacked up against John's. My answer is that John's boats are not as good for what I want. I could do the same analysis on a Hunter, a Bertram, a tin dinghy or any other sort of boat. Craig says But I don't understand the logic. Might as well compare the latest America's Cup moonohull to the 1760's schooner SULTANA. Sure, what do you want to compare? Their ability to cross oceans, their speed up wind, there absurd costs, there post race use? All these comparisons can be made. The fact that they are totally different does not void the worth of the comparison.
Subject: [MHml] Ballestron rigs From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Mon, 30 Aug 1999 08:14:56 -0400 To: multihulls list <multihulls_at_steamradio.com> Ted Warren says aerorigs..snip..meaning lots of carbon and heavy. Or lots of depth and width, and light. The weight from concentrating the loads at the mast has to be offset against the weight of the jib tack/attachment and the mainsheet attachments to the deck, and the weight /cost of the gear needed to trim unbalanced sails. For small rigs these weights/costs are small, but so is the load at the ballestron/mast connection. For big rigs, the ballestron wins every time. Incidentally, you refer to AeroRigs. No idea if this means you are using their weights or not, but our experience is that we can (and have) built ballestron rigs between a half and a third the weight of AeroRigs, and a heap cheaper. Building one for yourself (ie without all the add on costs to cover your posterior in the event of breakage), is even cheaper. Building a couple (for yourself) becomes very competitive, as the mould/heater/compressor costs are amortized. Ted it's an unsayed rig, which means that the spar will be heavier and the boat will be heavier to withstand the rig loads at the step. The spar, yes, but don't forget the weight, cost and short life of the rigging, turnbuckles and spreaders, nor the weight of the chainplates, jib and main sheet attachment points and the beefing up to support them. It becomes pretty close, with the cost advantage moving towards the unstayed rig over time. Ted Although simpler to design, an unstayed spar will always be heavier than a stayed one of equal materials and competency of design. Of course, but generally we are comparing alloy and stainless with carbon and the unstayed carbon looks pretty good. With medium modulus carbon prepreg available at $10/lb, it may be worth another look at your calcs. Ted The aerorig maintains good jib-main geometry off of the wind...snip..exact geometry of the aerorig at a fraction of the cost. True for a cat, Ross Turner has been doing it for years, but a challenge on a proa, trimaran or a monohull, I think. The geometry is only one of the advantages along with low loads and easy sailing. There is nothing stopping you putting up extras on an aerorig, or a wing for that matter, any more than on any other type of rig, as long as they are all designed accordingly. Ted I'm only impressed with the balance issue and ease of control of the aerorig..snip..but discarded it after calculating the size and weigh of the balestron. No doubt at all, but for a larger boat the numbers become a bit more skewed towards the ballestron. How is Tiny Dancer (brilliant boat, by the way, puts my rough and ready proa efforts to shame) going? Any race results against conventional boats yet?
Subject: [MHml] W From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Mon, 30 Aug 1999 08:15:02 -0400 To: multihulls list <multihulls_at_steamradio.com> Mike Nicholson says This afternoon a friend rang and said "Boy, I've just seen this really ugly catamaran." snip I would hate to think that the owner had given up developing the concept. It is a bit ugly, isn't it. Looks better at full beam (7m instead of 4) with the aft beam in place, sails up, tramp on and the accomadation off. Looks much better at 10 knots with barely a wake, one hull pointing up, the other level. The pod was put on to enable us to qualify for the Coastal Classic. About three days work (much of it discussing the least ugly way), and then they wouldn't let us enter. Probably fortunate as there was a bit of work to do. White undercoat to keep the sun off. We weren't sure what changes would be needed, so a gloss job was put on the to do list. Probably looking a bit chalky by now. Told him he should have used house paint.....Looks like the accomadation on Harry will work, so it is likely Gray will use a similar arrangement on W. Helps solve the tramp load problem too. Sails in both directions, extremely well, but not yet in a breeze or huge seas. I emailed Gray for a state of play report and he replied he has been in Holland for the last 6 months and has taken up mussell farming. Unfortunately on W! Promises to have it ready for the AC if I get over there. I would hate to think of him giving up as well, although like a lot of other innovative types, the last 5% is the big problem. (95% done, 95% to go...). I am sure Gray is open to offers to maintain and improve the boat in return for use of it. He is a very approachable, laid back sort of dude. Incidentally, W is not really a proa, more a cat, strictly speaking. Probably need a new name combining the two. Prat, or Coat, or something. Then again, probably not a problem as it is unlikely anyone else will want one, at least till the bugs are out. regards, Rob
Subject: [MHml] S&S beater From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Mon, 30 Aug 1999 08:15:14 -0400 To: multihulls list <multihulls_at_steamradio.com> John Metza asks Can I kick up the windward rudder? Which windward rudder? See my prior posting on rudders and harry/U articles for reasons why spades make sense. John asks Kurt Hughs..snip.. would be difficult. Cylinder moulding is quick, cheap, stiff, strong, and easy, especially for mostly parallel buttock lines hulls (like a proa lee hull) and wide beams, as on a single beam proa. Foam/epoxy is a nonsense. Epoxy is the resin, polyester is the alternative, almost as good if you are careful. The reinforcement is either glass, carbon or kevlar. All have their pluses and minuses which I will go into offlist unless lots of people want to read it. Foam/glass, vacuumed, will be a little lighter than cylinder moulding for given stiffness, and probably strength. Foam/kevlar will be much lighter, Carbon/foam lighter again. You can (less than a week) build a long (60' rather than 100') cyl moulded proa hull (either in one hit or in sections with butt straps) from 45 sheets of 1/8" 6 x 4 door ply, and another 12 sheets of 1/4" for the deck, or a glass,kevlar or carbon/foam lee hull (takes longer as you really need to build an airtight mould), expensive because of the materials and the consumables. I built the mould and two half hulls for W in about 14 days. This was a much trickier mould (shape and inserts) than would be needed for a proa. As I said, when you are ready to decide, I will talk to my engineer about the length/material/wetted surface options. John says I hope ..snip.. these emails. No, it is raining. When it stops, (tomorrow by the look of things) you may not hear from me for a while. There is some talk that I am leading you astray, but i figure you are big and ugly enough to decide for yourself! Ian farrier said Hmmmm.... so the owners of my designs are dopey...something to keep in mind. Cut it out, Ian. You have dealt with me long enough to know that I would never seriously criticise you, your owners or your boats. This triumvirate was responsible for a significant part of my epoxy business revenue and has done more for the general acceptance of trimarans worldwide than anything else. Got to be a good thing. I thought it was dopey to spend $140k on a 24 footer. Still do. Anyway, looks like I was wrong, someone who knows him much better than me reckons he is not dopey, but ridiculous (see below). Joseph Oster says Well Rob, ..snip.. Speaking of brevity, it would be polite ..snip.. Robust discussion is what i thought as I wrote it. You did tell me I was quite wrong, and leading poor innocent Mr Metza astray. I responded. Sorry if you are offended. Equally sorry to waste all that bandwidth. I shortened the rest, but missed Len's. Brevity is a wonderful thing, but not at the expense of clarity. You said "I can only go on my own experience hanging around a few multihull projects over the years, usually watching more than working (though I've slathered a good deal of epoxy here and there)". I didn't think watching or slathering is a good enough basis to advise John on the merits of an S&S beater for $30k. Still don't. Less brevity and some more details of relevant experience could have (and still can) avoided my apparent misunderstanding. Joseph says If the boat..snip..we must compare apples to apples. For the last time. A proa such as john envisages, would not be an apple. It would not be finished like an apple, it may not even fall apart after one season. It would not have the same sails, rig or deck gear as the apples. It would be different, fast and cost less than 30K, based on my limited experience with W,U and Harry. Joseph says I didn't say snip well. Sorry, this does not make sense to me in the context of john building his own boat. Joseph says Thanks man, I've been there and done that more than my modest claims apparently indicate. Don't be modest, man. Maybe a web site so we can judge where you are coming from, experience-wise. Joseph says This sounds like "Don't confuse me with the facts!" :-) See apples bit above Joseph says The "so what" snip break his budget. I am not leading John anywhere. He asked if I could build a boat capable of beating S&S. I think I could, based on my experience and all the numbers/ratios which are normally used to assess these things.. I would no more promise it would beat S&S than Bruce Farr guarantees to win you guys the AC. I leave it to John to decide whether he would rather try and maybe fail, or spend the money and time elsewhere. Next time I have 30K for a boatbuilding project I will certainly have a go. A project like this is meant to be fun. To build, to experiment, to have a go, to go fast and all going well, to beat the big boys. It is not supposed to be the definitive answer to the meaning of life. Until you understand this, you will never understand my (and I suspect John Metza's) motives. I suggest you save your time and bandwidth and live with the fact that we are a pair of dreamers/fools/wastrels. Despite all this, if you are in the Chicago area September 2001, say hello and come for a blast. John Dalziel says Rob, Joseph is right snip. John, Joseph is wrong. Do you guys cost the time it takes you to read a novel when you buy it? Building, experimenting and sailing are all part of the whole experience. IT IS MEANT TO BE ENJOYABLE. I don't enjoy fairing and painting. It does not help me achieve my ideal boat. Therefore I don't do it. Look forward to taking you for a sail as well. Joseph says I assure you my friend isn't "dopey" at all. That amount of money on a small boat sounds ridiculous to me too You said it... Joseph says I question the logic of only 60' of waterline on a 100' proa with 20' on each end as wave piercing overhang. Me too, John too, although wave piercing, as I understand it, is not overhang. It is hull which has no purpose other than to part the water. Therefore, it does not need to be strong enough to support rigging, rudders or beams, just keep the water out. Dave Culp ....Joseph Norwood I guess I better see what all the fuss is about. What's the cost of 21st Century etc, and do you guys accept credit cards yet? Sorry, no easy Web access. Is there anyone in this game that you don't know??? Joseph Oster says As Ted pointed out, "the basic problem that you need much greater downwind sail area to achieve good VMG" cannot be ignored. I don't believe wing sails alone can solve it so a screacher or spinnaker will be needed to be competitive. True. As windsurfers, C class cats, Tornados will all vouch for! Gosh! Beating S&S downwind in the light will be a problem. Just in case this is the breeze we get, perhaps we should forget about it and go back to mowing the lawn on the weekend, and watching TV in the evening. Ted also pointed out that proas are a different ballgame. Actually, what we will do, is offer a sail on the boat for the use of a screecher for the race. Bet we have more offers than time to take them all sailing, and that Mr Fossett is at the head of the queue with the best and biggest screecher you have ever seen, and that Goss is not far behind. Do a similar deal for borrowing the safety gear. Let's maybe go one step further and build enough of the boat to inpress a sponsor. $15K or so for your company name plastered all over the most photographed/filmed/talked about boat in the fleet. Even if it comes last, even if it breaks before the start; Ask anyone at the start of the first Route de Rhum which was the boat they remember. Bet they say Rosieres, the 60' long x 80' wide proa which fell over at the 10 minute gun. How's that for changing the rules, Mr Curmudgeon! Incidentally, a screecher off a wing is not difficult, structurally or aerodynamically. What may be different is where the tack is attached for optimum efficiency. The rest of Josephs comments are dealt with on the Harry vs log boats thread. regards, Rob
Subject: [MHml] harry vs log boats From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Mon, 30 Aug 1999 08:15:44 -0400 To: multihulls list <multihulls_at_steamradio.com> Joseph Oster says NOTHING AT ALL!!! snip Where is the "common sense" in having a shorter hull carrying most of the weight most of the time? Wrong way round. Make the weather hull comfortable with the weight it needs to carry, then make the leeward hull as long as convenient. The fact that my garage may not be long enough doesn't alter what is required. If I describe Harry as a 24' Pacific proa, with a long leeward hull, does this help? You need the righting moment. How are you going to get it without loading the windward hull? Running crew? Sails which lose drive/heeling force under high wind loads? water ballast? bearing away or luffing up when the weather hull lifts? None of these satisfy my criteria, so i put the accomadation there. little slower up to log flying breeze (plus a bit), faster from then on, as the log boat must be overpowered at log flying stage. A lot more comfortable always. Joseph says With more than 50% snip are both speculating here No speculation. Compare it with a F40 cat (wt ex crew 1,900 kgs) running downwind with all 5 crew (and on really scary days, extra sails, water and anything else that's portable, 600 kgs maybe) in the weather hull. The chances of flying the lee hull? not large. > > The shortness of the windward hull on harry may well be a problem, > > it certainly is on U. Joseph says Aha! snip Harry bears little or no resemblance to my definition and analysis of the Pacific proa! Semantics! First cousin to jargon. If Cheers is the definitive Atlantic proa, the critical requirement is that the beam is loaded in bending and the rig is on the windward hull. Harry's aren't. To be honest, I don't care whether Harry bears any resemblance to your definition and analysis of a Pac proa or not. Assuming this is the same analysis as John's I am still waiting for the answers regarding it's speed, suitability for cruising, ease of building, accomadation, how the crab claw sail reduces heeling and the rest of the queries in my last post. If you want to exclude harry from the elite ranks of Pac proadom, fine. Let me know how the ruling body would like me to refer to it. > > John Dalziel says my whole essay WAS a comment on Norwood's prescription, as is explicitly noted in the essay, and in the question that led to it. My reply was in response to the question How does Harry match up to the claims in your essay for a log boat? I humbly apologise for any criticisms I made which would apply to Harry, but not to Norwood's prescription. I suspect most of these difference are of degree rather than total errors? John says If one of the professional designers wishes to answer the weight point with specifics, let him. They have. Assuming lightness is what pro designers aim for, name the lightest 40' cat around. Now the lightest with headroom and 2 double bunks. To paraphrase the estimable Mr Warren, proas are a different ball game. John says " And the cat will have the faster (one-way) hulls, which will more than compensate for weight gain implied by the need for stiffer beams. Harry, as a cat, would be faster than Harry the proa." Which is a statement you obviously choose not to dispute. Sorry, missed it. I do dispute it. The speed gain from one way hulls will not come close to matching the speed loss from heavier beams, longer windward hul, 4 foils and the additional sail required to drive it. Long skinny hulls are not going to be much slower regardless of whether they have a transom or not. Check out rowing sculls. Check the waterplane of almost any fast cat, pointed at both ends John says It seems to me that Harry has the accommodations of a 24' trimaran, mounted on a 40'er. I don't see where it would be any real chore to match them on a 40' catamaran. None whatsoever, which is why there are so many cats of this type out there, and 24' tris. None of the cats cost as little or weigh as little as harry. None of the tris at the same cost or weight have the accomadation. I may be wrong. let me know the examples. > > > > John says Again, the accommodation part of your statement is pure "bunkum," since it is plainly possible to build in better accommodations in the longer atlantic hull than in Harry's stubby one. No it isn't. For a start, they are not in the weather hull, but alongside it. Secondly, because there are no masts, beams or rudders (and more importantly, none of the loads from same) in the windward hull on Harry, the space is all usable. Have a look inside Cheers to see what can be done on an Atlantic proa. John says the stability advantage of the atlantic version is great enough that by rearranging Harry' materials as an atlantic proa..snip.. even given the same weight and type of construction. I suspect that it would need to be shortened more than considerably. And have less sail, and be narrower, and go slower, and be heavier. It should be noted that I have the advantage here, as I know what materials are in Harry, and you don't. Maybe someone will do some comparative numbers. The whole point of Harry is that the windward hull is supported by the shrouds from the masts. This triangulation takes so much stress out of the beams that it is impossible to match the weight with an Atlantic proa, cat or tri. John says And I think it is worth pointing out that your estimate of Harry's weight is of indeterminate accuracy since the boat is incomplete. Your lee hull _measured_ weight of 318# is over your original target weight of "250-300#." snip Your attitude towards the loads on the outriggers seems cavalier, snip, as was necessary on your earlier proa. So it is highly likely IMO that Harry will come out weighing _at least_ several hundred pounds more than the target weight. > > Touche. Especially the bit about U's beams. This is what happens when you acknowledge your stuff ups. Shock horror! 18 lbs difference between predicted and actual. Thank you for pointing this out. This is what happens when you bow to pressure to let everyone see your ideas before they are either plans or reality. Harry may well end up being twice the weight it was when launched (550 kgs/1200 lbs was the sum of the components, including the short rigs and the accomadation. Say another 10% (?) for errors, 610 kgs (1330 lbs)), say a tonne and a half. Still be lighter and cheaper than any other boat I know of built with the same accomadation, speed (based on numbers, as it is yet to be sailed) and cost. I think. Maybe not, in which case, let's have the details of the other boats. Heck, it may even end up 3 times heavier, in which case it may be a failure, and may make a good bonfire. Just for the record, what weight, speed, cost and other criteria would I need to achieve for harry for you to to rank it as a success? As a breakthrough? As a revolution? No waffling, just the figures. John says compared to other multis. Not so- they are about the same and possibly a bit slower." snip Speed for _length_ is not the strong point of the Oceanic (or Pacific) proa; The reasons for length are speed, space and very secondarily for easy motion. Beam is for righting moment, leading to speed. If you have both length and beam, but no speed, and no space gain (in a log boat's leeward hull which is empty, yes?) , what's the point? Easy motion, i guess, but if this is offset by the need to run up and down the beam, why bother? John says that _particular_ quote was contained in a private email to you so you are out of line in using it here. A bit precious I think. If you stand by it, you stand by it. However, if I am out of line, I apologise. John says I am tempted to respond in kind by quoting the outlandish performance predictions you made for Harry's snip but I won't... Quote away. I was wrong when I made them (and said so). I will still be wrong and will say it again if it makes you feel any better. Admitting error is all part of the testing process. The difference between quoting my outlandish comments word for word and mentioning in passing that I made them and threatening to publish them, is a pretty fine ethical line. You ever thought of a career in politics? John says In the meantime, maybe you should knock off the bragging and wait for Harry to prove your point. Sorry again. Didn't think i was. Harry is an experiment that has yet to work. Most of my postings mention this, or words to this effect. John says Or just polish the weeds off your other boat and go sailing. Touche again. Except W ain't my boat. What Gray does with it is nothing to do with me. He has expressed nothing but satisfaction with the design and the construction. The fact he is too busy to use it, or polish it, is his problem, not mine. OK, you have made your snide little cracks about U, W, Harry, my lack of morals, my excess of ego and my ex client's lack of boat care. I guess thay are warranted. I dish it out, I guess I can take it.. However, as you make no comment about log boats (except how slow they are), then am I right in assuming that my criticims of them, in my last post, are correct? What's with the Harry Bare Naked title? A reference to me being totally up front with all aspects of the design and building, or a slur on my painting ability? Hans Dieter Bader says No, they actually buy a cheap runabout. They know how much it costs to build a boat and the know that with the motor they get where they want to go (at least most times). too true. I should have included the sailing bit. Hans says There was a windtunnel test at the Auckland University, which suggests for a 36 foot Marianas canoe speeds up to 19 knots. This is traditional building and traditional weight: around 1 ton. Now we're cooking. This is impressive speed and weight. Any other detail? point of sail, breeze, etc. Any idea who wrote it up? Or where I can get a copy? Hans says The easiest way to build would be in a female mould using stones and weights instead of screws or staples. Any spots with much loading could be strengthend with flax fibres laid in resorcinol. Do you have a better idea? Goodness Gracious! and they call me radical! No idea whether it would work, but definitely worth a try. Not sure whether the gap filling properties of epoxy would not be better than resorcinol, at least for the bamboo. Never tried to stick anything to bamaboo. I will and let you know. Epoxy is toxic, but wear gloves etc and it should not be a problem. As you say, its renewability is of equal importance. Anyone know the relative environmental costs of the major glue types? bamboo is a superb engineering material, I am not sure how good it is in non tube form, or with the bulkheads (correct word is??) smoothed off to allow gluing. Flax is also pretty good, although hemp has better properties. A mate played with woven hemp for surfboard sheathing a while ago. Worked almost as well as glass. The hippie surfies loved the idea. I have tried weighting foam into female moulds and it is a nightmare without vacuum, sand or water as the force. Male moulds are not much better, unless you tie weights to the gunwhale overhang bits, in which case it works well. Suggest you try some sample bits on the flat and proceed from there. Please let me know how it works. Another possible would be to use the bamboo rods as a space frame (lash the ends with the flax) and sheathe it with woven flax/hemp saturated in something safe. Unfortunately, the more waterproof it is, the less environmentally sound it will be. Maybe tar, like the irish horse trainer. Hans says you simply replace the outrigger with a second, smaller hull and fit a solid platform with a mountaneer tent Exactly what I would do, but I suspect my wife and her mates would not come along. Hans says The right size and position (and shape) of the sail on the canoe, is still the big X-factor. snip Please keep us up to date with comparisons. I would also appreciate some feed back about the performance of the crabclaw and it's apparent ability to diminish heeling. Hans says I am rather interested in proa behaviour in 60 + knots of wind and heavy seas 60 knots is interesting for everybody. If you need a hand testing it in these conditions, let me know. I assume you are in Auckland? Regards, Rob
Subject: [MHml] polyester/epoxy From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Tue, 31 Aug 1999 02:50:26 -0400 To: multihulls list <multihulls_at_steamradio.com> Marty Voss says your statement about polyester and being careful. I have been rebuilding an epoxy over ply 31' Cross Polyester can be used in foam sandwich boats and provide almost as good a job as epoxy. Epoxy has better long term characteristics, but assuming your laminate is not at the limits, this is not a problem. The big worry with both is to get a good bond to the foam. Precoating the foam with resin and squeegeeing it firmly is not bad, but vacuuming is far better. The problem is getting the resin into all the little part bubbles and hollows on the surface of the foam. With nowhere for the air to go, even squeegeeing has it's limits. Vacuum removes the air, the resin takes it's place and makes for a much bigger bonding surface. Warming the surface helps on cold days as the resin thins and the air expands, making release much more complete. Most sandwich failures occur between the core and the first layer, which is why this bond is so important. End grain balsa is not such a problem as the air tends to be displaced through the wood cells (I think, it certainly goes somewhere) and out the other side. The other reason for vacuuming is to ensure contact between the core and the laminate. Not a problem with small jobs, and nbot so bad when the laminate is placed on the core, But placing the core on the laminate with tight corners, large flats and recalcitrant cores is a recipe for disaster if they are weighted instead of sucked. Contour cut cores are easier, but need to be filled with bog before use. However, polyester and wood are a whole different ball game. Polyester is nowhere near as waterproof as epoxy (the Gougeons did some fascinating tests on this a few years ago. Available in a booklet from them) and is more brittle and nowhere near as good an adhesive. Consequently I would be very wary about using it for sheathing wood, and absolutely against using it for any wood gluing. Polyester does not cure in the presence of oxygen and leaves a sticky uncured surface, to which nothing except polyester will stick which is great for moulding boats etc in stages. Alternatively, it can have some wax solution added to it, which floats to the surface and prevents the air reaching it. However, you then have a wax surface to which nothing will stick. For these reasons, polyester sheathing of things that will be glued with epoxy is not a crash hot idea. Vac bagged polyester is protected form the air by the bag, so no problems with secondary bonds. Peel ply is another option, but adds to the cost. Plastic sheeting over the job is another option, if done carefully. Polyester contains styrene which addles the brain (use it in a confined space and come out giggling, but decidely unwell), and the catalyst blinds you if you get it in your eyes. Epoxy curdles the skin if you let it. Polyester lasts less than 12 months, epoxy much longer, although test anything for cure time and completeness if it is over 12 months old. Polyester cure time is short and easily varied, but don't go outside the limits. Polyester wets out most glass, and particularly chopped strand mat, much quicker than epoxy does. CSM used to be considered a necessity for interlaminar bonding strength, but these days is used more for bulking out the laminate. Polyester can be used with gel coat on a mould. No paint required, which is a serious work saver, but a lot of effort making a perfect mould. Summary. I would stick with epoxy for all the structure, everything wooden and anything which is to be secondary bonded. I doubt that the price/gallon of bulk epoxy will be much less than polyester in small quantities, so I would use epoxy on everything. If you want to play with polyester, start on removable bunk bases and similar non structural, non secondary bonded items. The osmosis thing seems to have been fixed. Modern polyesters are far better than 20 year old ones. Much of the osmosis I have seen was caused by lousy workmanship, voids, foreign matter, non wet out glass, poorly mixed or measured catalyst. I would still use vinylester as the tie coat under the water on a moulded boat, or coat it with epoxy, but the chances of osmosis are increasingly rare. Marty asks: Keeping in mind that I am not involved in organized racing do you believe that a home builder with moderate skills can build a fairly fast multi of 35' or so using polyester resin? No problem, but my experience, and that of thousands of home builders is that a wood/epoxy boat will be quicker, easier, more pleasant and cheaper. A polyester boat is best bought as hull and decks from a reputable builder, beg, hire, borrow or steal a mould for a couple of weeks, get all your mates round and build a hull and decks. Far cheaper and faster than any timber technique. Make sure you like the boat though! Strip plank foam is another possible, where one side of the foam is glassed with uni, then cut in strips, screwed onto formers, unis down, glassed on the foam side, removed and more laminate added inside. Light, but expensive due to core costs. The cost of the core is more than offset by the cost of the resin . I would look at sheet ply (seriously shape limited, and with a poor reputation due to polyester being used instead of epoxy), cylinder moulding (some shape limits, but very quick and cheap for the hull), constant camber (slower and ditto), then strip planking, which is incredibly popular because it provides curvy shapes, easily, but is huge work to fair. Cost of the hull is pretty small beer compared to the overall boat. Weights should always be compared as absolutes. A 10% weight gain is great, but saving 1lb per sq ft off 10 lbs per sq' at the additional cost of $50 per sq' needs close analysis. Costs vary regularly. Glass here has just dropped by 25%! Material suppliers love to bargain! Ask around, but watch for quality and service as well as price. Get the teenager involved. Good source of cheap labour. Failing this, send him/her out to work asap to pay for it! Hope this helps, Regards, rob I would be interested in your thoughts on carbon/glass/kevlar, but am also interested in your statement about polyester and being careful. I have been rebuilding an epoxy over ply 31' Cross tri for the last year, it is sailing now and I am looking at the end of the project, perhaps another year of weekend work....so I am looking at what to do next, and the cost of epoxy keeps going up. Keeping in mind that I am not involved in organized racing do you believe that a home builder with moderate skills can build a fairly fast multi of 35' or so using polyester resin? The way epoxy has been touted as the best thing since dacron, and with the blistering problems that have been associated with polyester I would have until recently not considered this. However as I have said the costs keep rising, and raising a teenager has forced me to reconsider the ways open to me to spend what I make (and am allowed to keep).
Subject: [MHml] Harry vs log boats From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Tue, 31 Aug 1999 02:51:12 -0400 To: multihulls list <multihulls_at_steamradio.com> Joseph Oster says The "slap, dash, bing, bang, boom" school of naval architecture, eh? Presume this is meant as a cheap dig, but actually it is pretty close to the truth. Difficult to find books/instructions on designing boats like harry. Even harder to get feedback from people who have done something similar (log boats) but who are so hidebound that they refuse to discuss the limitations of their ideas. This does not apply to all log boaters. Those who have actually built boats have been very helpful. On the basis of this, a fast proa would look more like a log boat than Harry Joseph says You need a precise amount of righting moment for a given rig.... snip.... We know all this. Answer the question, how are you going to get it? Joseph When you first announced Harry on this list July 9th (seven weeks ago!), you made the following statements: Why the exclamation mark? Too fast, too slow, too what? How does it compare with other projects you have watched? 7 weeks ago I have just finished building a 40' Pacific proa (named Harry) I had. Not gloss painted, not even particularly fair, certainly not tested enough to make any factual statements except for weight, cost and time to that stage. All held together with bits of string until i knew what worked. If you are querying my use of the word "finished", then you are undoubtedly right. It wasn't, and probably never will be. However, in the interests of brevity, and on the understanding that readers would understand that what I meant was that the hulls, beams, rigs and foils were ready for testing, I settled for 'finished". If this misled you into thinking the golden age of proas had arrived, please accept my apologies. 7wa not launched yet (waiting for sails and tramp, should be sometime next week) It wasn't, they were, but did not work as well as I hoped. Tramp too soft, rig details too complex. I launched it anyway, and motored around for a bit to test steering, power requirements and admire the clean wake from the short windward hull, then decided to fit the accomadation while i figured out how to make the rigs work. Since then it has rained as often as not, and as Harry is in ankle deep mud in the middle of a mosquito infested mangrove swamp, in the open, not much has been done. This has given me the opportunity to ask for feedback and to point out some misconceptions. The feedback has been interesting, but unfortunately, much of the list postings have been personal to me as people do not like their partially formed, untested, but maybe interesting ideas being shredded publicly.. 7wa it weighs about 1,000 lbs (this is the weight of the components harry launched, ready to sail weighed 400 kgs (plus or minus a bit as component weighing is dubious). Since then I have added the accomadation, weight another couple of hundred kgs (even more dubious as it was not weighable). I have neither the ability nor the interest to weigh harry until it is complete, and probably won't bother even then if the result is that my credibility is doubted for being 6% out on an estimate made at the very beginning of the project. And yes, I have done the figures. A similar error for John Metza will cost him another $1,800. 7wa Or [for $30K] build a 60 footer which would weigh less than a ton and have well over 1,000 sq ' of sail. Still think I could. If John Metza is not put off by your accountants theory of boatbuilding, maybe we will find out. now "twice the weight", "another 10%"... Heck, it may even end up 3 time heavier, in which case it may be a failure, and may make a good bonfire. Still might. this is the nature of experimentation. This was not written as facts, but as possible outcomes after testing. Given the above answers to your statements of mine over the last 7 weeks!, I have to ask you. What is your problem? Joseph says I enjoy the honesty you have expressed in your Harry and U articles and admire anyone who is actually building proas or, for that matter, multihulls of any kind. You may well admire me and my efforts, but if this is the way you show your admiration, it is little wonder that so few people are willing to put their ideas on line for you to tear them apart on the basis of a lot of watching other people work (another unanswered question) and apparently very little else. I know of 4 other proa projects, the owners of which are not willing to go public until their boats are sailing. I think this is a shame (for them and us), but cannot really blame them. I want feedback on Harry. I want people's opinions on what will and won't work. Good ideas, I will try, others I will see if I can modify. Most of my ideas stem from other peoples input. What I don't need is holier than thou insults because it does not fit neatly into one of your little boxes. Joseph I believe, Rob, it is too much effort to sort out the reality behind the myth, especially when it doesn't bother you at all to make bold statements that you must later retract. I believe, Joseph, that if you read what I have written the reality is obvious. I also believe that, in your usual nice, sweet, charming, non offensive way, you are calling me devious. List my retracted statements, and I will do my best to say why, but can already tell you that if there are any, they are probably based on the results of testing, trying or advice from others. Anything you can't distinguish as either reality or myth, please ask. Let's get a few things straight before you go. You and others wanted some details about harry, I supplied them in the form of an article written when harry was little more than a twinkle in my eye. Harry is an experiment, according to you a totally new kind of boat. (Another question you have not answered). What I said (many times) is that I won't have everything spot on, and some of it won't even be close. There may need to be some alterations and additions. It may end up weighing more than it now does. It may be a total dog. I know this is anathema to people who won't try anything new until it has been fully tested and everyone has one, but it is pretty normal for an experimental craft. I ask you the same question I asked John Dalziel Just for the record, what weight, speed, cost and other criteria would I need to achieve for harry for you to to rank it as a success? As a breakthrough? As a revolution? No waffling, just the figures. This thread started because I was asked to comment on John's essay about log boats as they compare to Harry. I did, and asked the log people some questions. Most of these are yet to be answered, particularly about performance and righting moment. You have turned it into a criticism of Harry based on five eights of very little information, and all of that with the knowledge that Harry is an experiment, and as such bound to be changed. Hopefully, you are also stopping your negative campaign on John Metza's idea as well? Good. Now perhaps we can get on with designing it and finding out what the limits really are. Ideas on this boat are needed. I am sure that anyone who contributes will be welcome aboard for a sail. They will certainly be welcome to help when it is being built! Signing off a thread when you are wrong is always going to be difficult. Seems there are three ways to do it. 1) Just stop contributing. 2) Admit to being wrong. 3) Say you are quitting the discussion, then make nasty remarks and insinuations so that you can be seen to have the last word. Perhaps some of the people for whom etiquette is more important than content could have a look at this and see if they can come up with a better system or even a neat little abbreviation. Maybe IWW, S would do the job. regards Rob PS This time next week Harry will be painted (weather permitting) and I will take some photos. If I scan them will you put them on the web? At least then , the knockers will have something visible to base their criticisms on, even if it is only my crappy workmanship.
Subject: [MHml] I was wrong, sorry. From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Tue, 31 Aug 1999 02:51:17 -0400 To: multihulls list <multihulls_at_steamradio.com> John Dalziel, I have been told that quoting your private communications on the list was a serious breach of etiquette, and, worse, an abuse of confidence. If I had thought about it before posting, I would have realised that this is obvious. I didn't, and I am sorry. Please accept my sincere apologies for any embarassment this may have caused and for my trite little insults when you pointed it out. I hope we can still continue our debate on the list, or off it if you prefer. Regards, rob.
Subject: Re: [MHml] Ballestron rigs From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Tue, 31 Aug 1999 17:56:19 -0400 To: multihulls list <multihulls_at_steamradio.com> Dave Culp says You didn't say anything about the stay from mast top to ama, Rob. FWIW, making a wholly self-supporting rig on a pac proa is an oxy-moron snip Two of the strongest points of the genre, snip 2) "perfect" construction geometry: no bending forces in the crossbeam; only pure compresssion in mast *and* beam. Strengthening Rob's case for ballestron rigs (can we call 'em aerorigs? Easier to type.), particularly as these grow larger. Absolutely. A pac proa without a shroud is like foam without glass. Floppy. And perfect construction is a brilliant and apt phrase. I didn't defend it because I thought Ted was referring to aerorigs in general, probably because I got caught up in his general comments on unstayed masts. The problem with calling them aerorigs is that it is possible to make them much lighter and cheaper than Carbospars do. We built 3 EasyRigs, which were all way lighter than the Carbospars product, which, according to people who have been there (dubious I know, but there mucst be some explanation for the weight difference), has a lot of glass in it, presumably for toughness. I have dropped our all carbon ones from reasonable heights and done no obvious damage. Difficult to tell I know, but static bend tests revealed no cracking noises up to the design loads. Our prices were about the same as a conventional rig, if all the fittings and beefing up were included. This is much less than Carbospars charge. Build them yourself (possible with small to medium sizes without an oven) and the price, even including the mould is much cheaper than an alloy and stainless rig, with all the attachments. With the price of carbon dropping, this will only get better. During your big proa thread I got the impression there was a lot of information available on wishbone rigs. Could you tell me where I should look, please. No, I am not giving up on wings, but another proa builder can't wait for me to get my act together. Can't blame him, I guess, but it's the bloody weather. Dave Culp
Subject: [MHml] Roy Mills' proa From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 1 Sep 1999 18:42:20 -0400 To: multihulls list <multihulls_at_steamradio.com> Roy Mills says twin rudders in dagger boxes, symmetrical ogival in section so they would work both ways if it proves that they are both needed for balance or leeway fighting. The bow rudder could be given a bit of incidence, via its tiller, if needed. Sounds good. The only things I would watch are the rudders working in both directions. The centre of balance is at about 25% from the leading edge, so they will be unbalanced/hard to use when it is 25% from the trailing edge. Apparently Ted Warren has a tricky way round this. Alternatively, if they are in casettes, it is easy to make them turn through 180 degrees. My other comment would be that if you have 2 rudders anyway, make em bigger and forget the leeboard. Roy I really fancy the idea of a balestron type rig, ..snip..So, with its shroud, it would not be able to spin through 360 degrees, but it should be able to make it through about 358 degrees and I only hope to need a bit less than 180. Perhaps the required stiffnes of the boom could be provided at reasonable cost by spectra type rope in tension along the bottom of it, and Cedar in compression along the top. A Ballestron rig makes sense on a proa as the single sheet means there is less rope to pull when you shunt. Multi purchases mean miles of spaghetti. A wing mast should improve the ballestron significantly, if the mast rotates seperately from the boom. We have found that the centre of effort on a ballestron moves fore and aft a lot, particulalrly in gusty conditions. Too close to the mast, and you may find that you need to push on the mainsheet to ease the boom! The tension member on the bottom of the boom makes sense. I look forward to your results. Not sure I would use spectra, carbon has less stretch, and can be epoxied in place. If the bom is above the deck, the spectra would make a good vang from end of boom, to mast at deck level, to other end of boom. A stayed boom. You don't need 360 degrees, the shroud is the only way to go. Watch your cockpit set up, though, yo don't want the shroud in the way. maybe a split above head level, one to each beam end? Roy The LOG. we have lots of those of varying size all over our beaches, free for the taking. snip..perhaps two single berths,and a seat anyway, with wind/water screen both ways which joined with a tarp or similar would make it snug at night even if it rained Do your weight numbers carefully. The weather hull may need to be quite long to fit this in and stay skinny. Light weather performance will be affected, although if you get tricky with the beam attachments, it may be possible to vary this, on the beach, for different breezes. Roy The leeward hull would still have a leeward projection to provide a float to assist in capsize resistance but it would be clear of the water until quite a bit of heel developed, perhaps 20 degrees, who knows. I need to build one of these at some stage, or go for a sail on one. (Hint, hint!) Seems a mighty lot of drag, plus a nuisance coming alongside, plus weight in the worst possible place. Look forward to hearing how it works. Roy Getting now into the fantasy extrapolation, heeling would only occur in strong winds, and strong winds equate to speed, so maybe the leeward heel resistor could carry a foil or two. ..snip... try replacing it with a two sided aerofoil sail. Use the same mast, balance would be very similar and area could be similar too, See how that goes. Way to go. No experience with horizontal foils but others have, so it should not be too hard to find out what is required. If you are going to have the lump to leeward, may as well use it. Please share any thoughts on your 2 sided sail (off list, in confidence if it is secret). I am struggling with mine. Roy Might be nice to just sit and let the sail weathercock, fish, read, eat, whatever. No "might" about it. Roy Maybe the windward hull should have a flat inner side to slow down the leeward drift when engaged in these peaceful activities. Will reduce diplacement too much, I think. The ballestron rig has very low drag when feathered. Roy do not expect to build before 2001 anyway, so take your time. And I do not expect to build it to be thrown away quickly afterwards, although my estate might. I do expect to use epoxy, plus glass or carbon where appropriate and I do want it to look sleek, not ugly, and I do expect to eventually put a decent finish on it. 2001 is not so far away. Built it correctly, but wait until you have finished experimenting before going for the decent finish. It is heartbreaking to ruin a good paint job because you want to move the rudder cases a foot further out. Regards, Rob
Subject: [MHml] Harry vs log boats From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 1 Sep 1999 18:42:36 -0400 To: multihulls list <multihulls_at_steamradio.com> Hans Dieter Bader Aitmala, I.E., (1992), Performance prediction on the Pacific proa, University of Auckland, Dept. of Mech Eng., Project Rep PME 92-05..snip Thanks Hans, I will contact Prof Jackson Hans Good hints! The flax I talk about is NZ flax which grows on every corner. snip.. Know it well, I used to make skirts out of it for school concerts.The hemp I talk about is the stuff in half the back gardens! Has anyone tried gluing or treating the flax to make it waterproof? Hans The two spared triangular sail attached to the mast and to the boat at the tack gets a shape like a part of a cone if you let the sheet out. snip The Bermudan is only competitive close hauled. I understand the lower coe than the bermudan sail, and maybe agree with Marchaj's theories (although I have been told that the bermudan rig he used had huge twist. Any comments, anyone?). I am still not convinced there is anything special about the crab claw that reduces heeling. Could the reduction in heeling be caused by the reduction in projected sail area caused by the billowing? Does the sail billow automatically (stretchy sail cloth or ropes, or bendy spars perhaps?) Is the contention that the crab claw (CC) 1) lifts the leeward hull or 2) that it produces less heeling force for a given amount of drive force, and that the difference increases (ie even less heeling) as the breeze increases? If it only lifts the lee hull, this is a good thing, but does nothing to increase the righting moment, only the speed. Or am I missing something altogether? How do they perform to windward, in your experience, vs a conventional bermudan rig of same size in a similar size/weight boat. Hans But you mentioned to come to Auckland for the AC, please let me know and we have a sail (it could get funny though, as the Navy nearly towed me out of the starting area for a Whitbread race once - our old outboard died - and the wind too! Thanks for the offer. Definitely in February, maybe before. I once had a similar experience becalmed in the lee of Brittania. Bounced down the side until we hit the Royal Barge with HM just boarding. She was not amused, but Prince Phil was. Bob Lechner on clarification of proa thinking. You got mine right. Joseph Oster says Norwood was there long before you snip I never said he wasn't. John Dalziel said Harry "did not attain the Norwood prescription" or some such. You said harry was not a Pac proa by your definition. Seems by your definition it must be a new type? Joseph I did forget to mention one important point though: high performance catamarans (and tris) tend to pitchpole before they roll sideways. The same thing may happen for the Norwood/Denney proa sailed to maximum stability. And it may sprout wings and fly as well! What possible argument have you got for suggesting this pile of red herrings? Let's see the maths, or at least be told where it can be found. The pitchpole problem is actually an interesting one. My feeling is that a portion of the heeling force on a cat or tri depresses the leeward hull, due to the offsetting athwartships of the rig from the lee hull. This is not so on either a True Pacific proa (TPP) or an untrue one (UTPP?, surely someone can do better than this?), where the drive force depresses the hull, but the heeling force only lifts the weather hull. I stress this is only a feeling. Any comments, anyone? The 5m did not nose dive, U did, a little, until the beam was canted aft. Worse than the rigs causing a nosedive, is, I think, the crew and the bulk of the weight not being sited aft as it is on a cat or tri. This is more the reason for my choice of the schooner rig than to reduce the sideways heeling. It is also partly why the leeward hull is paralell for much of it's length. If I'm wrong, it is not so difficult to add another sheet of ply or two. Joseph The true Pacific proa with less weight to weather addresses this problem with the longer leeward hull using the same rig as a catamaran of similar weight. There are some very specific numbers available to support this if you do the math. No idea of the math for pitchpoling, but wonderful to at last have some righting moment answers. Let's look at the math for righting moment. The righting moment of"a cat of similar weight to the TPP" is 50% of the total weight * the hull centreline to centreline beam. The righting moment of the proa is the weight of the windward hull, plus half the weight of the crossbeam* the centreline to centreline beam. If the weight of the weather hull in a TPP is 25% of the total weight, and the beam, say another 10% (probably less than this), then the TPP has a righting moment only a little more than half that of "the cat of similar weight" The cats stability is further enhanced because the crew can and normally do, sit to windward in a blow. The TPP, with all it's accomadation, steering etc in the leeward hull cannot. Therefore, i would suggest that the reason TPP's do not pitchpole (if indeed they don't) is more to do with the fact that they can barely carry half as much sail in a breeze, than anything to do with hull length. They cannot carry the same rig, have the same righting moment, the same all up weight and have only 25% of the weight in the weather hull, unless they are almost twice as wide as the cat. 25' wide on 68' long (your design, see below) does not achieve this. Nor do any of the log boats i have heard about. Joseph Any boat where the weight of human crew is a significant percentage of total displacement has fundamentally different design criteria than a more fully loaded cruiser. Who said anything about a fully loaded cruiser? Start another thread if you want to discuss this. Harry is a weekender for me, the wife and 2 friends. Glad you have finally come to grips with the fundamental design differences. If the crew are a significant part of the displacement, it is critical they are in the best possible place, to windward. Harry achieves this. Always. There is no need for the crew to go to leeward, except to raise or lower sails, at which time, the capsize risk is minimal. Joseph I have analyzed this in considerable detail with respect to a cruising proa of 7..8 tons and am confident about the main (leeward) hull being the proper place to carry the majority of the weight. The principals of yacht design still apply, even to proas. Another fundamental difference, this time in approach. You can carefully analyse forever, but until you build something you can never be sure. Start with something small and get bigger as you find out that analysis is not the whole story. There are no successful yacht designers that I know of who did not start on small boats and work their way up. Which priciples of yacht design say that all the weight should be to leeward? Joseph As to "6% out on an estimate", I've heard numbers between "harry launched, ready to sail weighed 400 kgs" ranging up to 610 kgs. and "it may even end up 3 times heavier". I have explained this twice now. No one else had any trouble understanding it the first time, much less the second. Joseph It still might not be the design I would choose for myself ..snip.. Doing it at 20+ knots requires a Pacific proa with 75%..100% displacement on the main (leeward) hull that can routinely lift the ama. See above about a new thread for world cruisers and boats for you. As to routinely flying the ama (windward hull for all those who don't speak polynesian), all I can say is that you need some more sea miles. Are you seriously saying that your design will regularly lift the windward hull while cruising? Assume it is doing this, and that you are on automatic pilot, or tending the fishing lure, or just watching the sunset, and that a gust hits. What happens? You either capsize, or you heel to a large (over 45 degrees) angle before, if you are lucky, the weight of the log is countered by the breeze blowing along the sail, instead of against it. Add in a swell , and the angle could easily hit 90 degrees. This is not cruising, this is lunacy! I will assume the 100% displacement to leeward is a typing error. If not, please provide details, this is just what John Metza needs. Joseph I am reluctant to divulge too many details of our analysis or make unsupported claims... But I'd be very disappointed if the 68' cruising proa can't hit 21 knots in a stiff breeze... The hull centerlines are 25' apart with 25% displacement in the ama. Talk is cheap. 21 knots sounds like an unsupported claim to me. I doubt the speed will disapoint you, we regularly do that in moderate breezes in a 38' fast cruising cat. However, the first time your dinner is dumped on the walls, you are going to be mighty irritated. I didn't want any of your top secret design details, I just wanted to know where the righting moment comes from. Appears there isn't any, or not much, anyway. Rob, I will take some photos. If I scan them will you put them on the web? Joseph I'll consider it, though my server disk space is limited. One photo is literally equal in file size to five times the text in the Harry article. Don't worry about it, save the space for log boat stuff. Anyone who is interested can email me direct. Thanks again for the web stuff you have done for me. I do appreciate it. I do not think much of your proa theories, but you do have an excellent web presence. Joseph says I would also appreciate more mutual respect and much less hostility and personal attack in this debate! You are giving as good as you get! For those who are interested, the weather hull on harry is now weatherproof, except for the hatch, which will stay as a tarpaulin for awhile. Looks most peculiar, but hopefully a coat of paint will conceal some of the funny bits.
Subject: [MHml] Vacuum Bagging From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Tue, 7 Sep 1999 04:35:34 -0400 To: multihulls list <multihulls_at_steamradio.com> Lee Vogtman asks about vac bagging SP sysytems has some good literature, as do Airtech. Vac bagging is one of those black arts which after the first time, you wonder what all the fuss is about. The trick is, not so much how to do it, more how to do it at non aerospace costs. Bagging needs a pump, a gauge, a bag and a bleeder. While a shop vac will work, it won't pull a good enough vacuum for thick laminates, optimal resin content or sharp curves. Try a milking pump if you know any dairy farmers, or apparently fridge compressors work well. Second hand pumps are also pretty good value. Mine is now 10 years old, lives under an inch of dust, and as long as the oil is topped up occasionally, never fails. It is also possible to hire them from some suppliers. To get the air out of the bag, you need to get the hose in and sealed. The expensive way is a machined alloy fitting. The cheap way is a piece of copper pipe epoxied into a piece of ply with slots on the bottom to prevent resin from being sucked up the tube. Cheaper still, and less likely to cause problem at the take off is to tacky tape the tube into the bag. It is important that there is plenty of bleeder on the end of the pipe to stop resin absorption. Resin going up the pipe is no big deal, it can be cracked out later. Resin getting as far as the pump is a disaster. The gauge should be placed as far from the vac take off point as possible, and should read the same as the gauge on the pump, otherwise you have a leak. Full vacuum (1 atmosphere, 15 psi) can boil off some of the volatile components of some resins. Check with the manufacturer, although in reality, the higher you can get, the better the job will be. Builders plastic sheet works for the bag. Clear is best so you can see what is happening. The thicker the plastic, the better, as it is less likely to puncture and will stretch more to bridge corners etc. For high temperature jobs, special plastics are available. The bag is held to the mould edge with tacky tape. Window sealant tape works well, blue tack doesn't. The important thing is to keep the bag and mould edges scrupulously clean.Nothing sticks to wet epoxy. I usually put the tape on the bag prior to mixing resin. Leave the backing tape on until you are actually sticking it down. Taping the edge of the mould with packaging tape keeps it clean during wet out. Tacky taping the bag means that any tucks or folds are easily sealed by taking a dart in the bag. Make the bag well oversize to avoid bridging problems. The bleeder cloth is polyester fluff, the same as used for shoulder pads in dresses and as house insulation. Available from clothing and building material suppliers, but only in huge rolls. I have used old carpet successfully. The bleeder must release from the laminate when cured. Peel ply and perforated plastic are the standard materials. I generally leave out the peel ply and save the $3 per sq m. The perf plastic leaves a worse surface, but it is easily ground for secondary bonding. Perf plastic can be made by folding a sheet of plastic into the smallest possible square and punching it with a sharpened awl. Hole size is not important up to 2mm dia (more than this and the bleeder will be hard to remove), nor is spacing, as long as there are plenty of them. Use the slowest resin you can, and if gel time is a problem, work late at night/early in the morning. You should end up with les than 50% of the finished laminate as resin. Try to only use this amount, but ensure all the laminate is wet out, particularly round the edges Practie on something small first to get the hang of things. The trickiest bit is sealing the bag. A handy tool for this is a stethoscope to locate the leaks. Otherwise, hold your ear close to the edge and the leaks will show as a hissing noise. The more you seal, the louder the hisses. Rubbing the bag over the tacky tape usually stops the leak. Hope this helps. Any questions, please ask Regards, Rob
Subject: Re: [MHml] Catamarans and The Thomas Crown Affair From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Tue, 7 Sep 1999 17:11:22 -0400 To: multihulls list <multihulls_at_steamradio.com> Joseph Oster says $169K for a used 40' trimaran!!! Imagine that! Must be those damn greedy boat builders again, charging for their labor and driving up the price of what really should be cheap boats... :-) And a HEAVY 4,000 lbs. too! :-) They must have used too much carbon fiber! <BG> (I'm being sarcastic folks! This is the hard reality of high performance multihulls as I know it) Sarcasm doesn't become you Joseph. There was never any doubt about what you know on the subject of high performance multihulls! This is why it was important that your views were not allowed to dominate the discussion on other ways of going fast. By the way, you forgot to mention that RWS has no accomadation and is totally unsuitable for anything but day/overnight racing. Or that it probably costs half it's purchase price per annum in maintenance, replacing worn out/broken gear and mooring fees and needs a crew of at least 4. Still, I bet someone buys it. RWS is an excellent example of what you get when you limit design with length/beam/weight rules. A lovely boat, but for less money, they could go a heck of a lot faster. regards, Rob
Subject: Re: [MHml] Catamarans and The Thomas Crown Affair From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 8 Sep 1999 17:19:04 -0400 To: multihulls list <multihulls_at_steamradio.com> Marius says Let's assume the design goal would be to design the fastest all around boat for a given length (say 40 ft?, doesn't really matter , since you have to set a length for this exercise , why not 40ft ) . Why the fixation on length? A windsurfer was competitive with a 60' Open tri across the Med. I said that for the money spent on RWS, it would be possible to go faster. This would most easily be achieved by going longer. I suspect that just adding 5' to the bow of each hull would increase the speed around the track. Marius Are you saying it can be done cheaper and the resulting boat would be also faster ? What am I missing here? Two things. One, it costs more to design and build complex boats, which includes boat buit to a rule, than to design simply for speed. Two, small increases in speed are very expensive, once all boats are at the same level. What I would give up on RWS is the middle hull, 75% of one of the outer hulls, one of the beams, 50% of the structure of the other beam, the trampolines, all the winches, tracks, pulleys, mast, running rigging, sheets and sails. The weight saving? You can guess it as well as I can. The cost saving on materials and labour would be of a similar proportion to the weight saved. I would then calculate (Bruce #, the square root of the sail area divided by the cube root of the weight of the boat) how much sail was required to achieve a slightly better power to weight ratio than the original, take 80% (or whatever superiority factor you want to assume for a wing over a conventional rig) of this figure and built a simple wing rig, maybe a copy of the one on Miss Nylex (old C class cat, the wing design of which has been published, so it's free) which was built relatively cheaply from non high tech materials. I would then make the long hull double ended (join the 2 bow sections from the outer hulls), put a rudder in each end (saving the weight of the dagger board and case), and hey presto, you have a Pacific proa, a log boat, no less. This would be slower to tack than RWS, perhaps a little slower downwind, unless we kept one of RWS's screechers and flew it from the ends of the long hull, but quicker, in theory, on all other points of sailing. I would then get my crew to spend their race running up and down the beam to keep the weather hull just clear of the water. Much more fun than winding winches, and no gunwh'l bum complaints. Marius Being a novice I always thought the higher tech and more expensive materials are stronger and lighter . snip obsolete or lower quality design(er)? Agreed, but there are (much) cheaper ways of using the high tech materials, resulting in a minor disadvantage, but at a major cost saving. I would disagree with the need for computer modelling and simulation ,CFD , tank tests , real life tests , scale models , etc), just to go faster than RWS. If you built 2 boats which were faster and the same, then sure, there would be some gains from all the stuff which keep designers in business, but to just go faster than a Formula 40, there would be no need. Marius So my basic question is for same boat length how do you cut costs , increase performance and quality , make the boat more useful Have a look at the Harry (linked through Joseph Osters proa page) web page for what I have done. I am not suggesting that this is the answer to everyone's requirements, or even that it will work, although what has been done so far, seems successful. It does show that there is more than one solution to the problem. Marius What would need to change in the F40 specs to allow those faster and cheaper boats for same length? The speed requirement is easy. Look at the rules for the class and ignore them. The ones i am aware of are beam limits(increase), sail area limits (increase), mast fore and aft size limits (increase) headsail requirements (eliminate), weight (reduce). These would all make for faster boats. But, as soon as they were all faster, then money would come into it, and the guy who spent most would win. This is a fact of yacht racing. It is not (yet) a fact of fast sailing. The F40 rules were an effort to stop the racing getting too expensive, and they were not a bad effort. Marius would be great to have a boat that proves Dick Newick wrong , wouldn't it? So everyone says, but very few of them are prepared to try something different. Unless you are willing to look outside what is considered the norm, Newick is dead right. A recent example of this is the ballestron rig. For cruising boats it is so much better than a rig based on a racing boats that there is no comparison, yet how many of them are out there? Very few. Why? Because yachties are very conservative people. Regards, Rob
Subject: Re: [MHml] Vacuum Bagging From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 8 Sep 1999 17:19:10 -0400 To: multihulls list <multihulls_at_steamradio.com> Gary Pearce says Nice "handy hints" stuff from Rob. Perhaps he would like to add a few tubular hints. Sorry, chaps. Tubes is how I make my living (occasionally). Much as I love you all, you will need to pay for this information. Lee Vogtman asks "It is important that there is plenty of bleeder on the end of the pipe to stop resin absorption." Do you mean the same plastic that you refer to later - the plastic that you put over what you are laminating? Is this just a perforated 'cover' over the end of the tube to keep epoxy from going up the tube? No. The bleeder is the absorber material. Carpet, fluffy polyester, etc. There should be a thick pad of this under the end of the pipe, and some across the end to prevent the bag being sucked into the pipe. The purpose of the bleeder is to let air pass through it, and to absorb surplus resin. Ideally, the end of the pipe and the associated bulk of the bleeder pad are not directly on the laminate. This can cause the laminate to lift around the edges of the pad. The perf plastic acts as a release fabric (nothing sticks to the plastic). The perforations are to let the resin pass through, en route to the bleeder. Regards, Rob
Subject: [MHml] Paint on carbon From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Thu, 9 Sep 1999 17:16:35 -0400 To: multihulls list <multihulls_at_steamradio.com> John Metza asks I am curious as to why Playstation's hulls were painted? Just for advertising? Looks? Safety? Cover Fairing compounds? Should Carbon be protected from UV? My carbon windsurfer masts are 6 years old with no UV protection and no signs of degradation or failures. Playstation was actually painted twice, as Sony only got involved at the last minute. The paint is for all the reasons you suggested, but primarily to protect the epoxy from uv degradation, a job for which, in my opinion, house enamel is eminently suitable. It is not painted inside, but this is partly to show off the incredibly neat woven carbon work which Cooksons do. Carbon is not affected by UV (kevlar is, glass isn't), but epoxy, and to a leser extent polyester, both are. If your mast is not damaged after 6 years it is either clear coated with uv barrier varnish, or it doesn't spend enough time in the sun. 3 months full time summer exposure in this part of the world will see epoxy start to be affected. regards, Rob
Subject: [MHml] Harry and U web pages From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Thu, 9 Sep 1999 17:16:40 -0400 To: multihulls list <multihulls_at_steamradio.com> I have just recieved an email from Joseph Oster informing me that the Harry and U web pages are no more. The message was off list so I cannot go into his reasons for doing this. They are nothing to do with Harry or U. Presumably the wish to inform people about proas is not as strong as it was when he asked if he could turn my articles into web pages. Anyone who cares, can ask Joseph. Anybody who wants copies of the articles, let me know and I will forward them. An updated article on Harry (Titled "Reality versus the Wish List") will be appearing on the Inside Multihulls web pages and MM paper pages when I get time to write it. Regards, Rob
Subject: Re: [MHml] Catamarans and The Thomas Crown Affair From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Fri, 10 Sep 1999 20:58:22 -0400 To: multihulls list <multihulls_at_steamradio.com> Joseph Oster says snip..., it takes a gifted sailor to handle a proa. Thank you for the praise, Joseph! Unfortunately it is misplaced. Sailing a proa is the same as sailing a cat, once the shunting system is sorted out. Ask anyone who has sailed one. No gifts are needed. It took a gifted sailor (Tom Follett) to come third in the 68 OSTAR in a proa, but this was because Cheers (my inspiration, love this boat, admire and respect Dick Newick, the designer) was undercanvassed/poorly rigged in light airs, and was too short/too skinny in the ends in heavy airs. It was nothing to do with it's being a proa. regards, Rob
Subject: [MHml] Cheers From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sat, 11 Sep 1999 20:01:14 -0400 To: multihulls list <multihulls_at_steamradio.com> Duff Sigurdson says "Am I missing something here? No respect to Dick but what exactly inspired you about a "under-canvassed, poorly rigged, too short, too skinny" boat? >From this brief description of the boat, I am inspired by the man but pretty suspect of the boat...." All I know about Cheers is from the book Project Cheers, (abvailable from ??????, but it is a wonderful read, even if you have no interest in proas) by Follett, Newick and Morris, who put it together. The undercanvassing was a safety option (these guys were seriously pushing the limits of what could be done in a multihull). The masts were square section and possibly oversized (safety again), with no effective vangs so the mains twisted a lot. The mains were roachless and had short battens (normal in those days, but without a vang, seriously slow). The schooner rig has enough trouble going to windward normally, (although it can, and has, been done), but added to the above, was not ideal. The bows dug in at speed. Follett was worried about pitch poling and even the addition of anti dive plates did not help too much. Fatter bows, or much more preferable, longer hulls would have solved this. It was also only 16' 8" wide on 40' loa. The steering/centreboard arrangement was not conducive to rapid shunting. Despite these details, and they are details, Cheers is/was a magnificent little boat. Before the sponson was added, and with the proposed wing masts, it was extremely elegant, apart from the 'orrible little dodger arrangement. To design and race this boat was a remarkable feat. My congratulations to all involved. As for looks, I doubt if any breakthrough boats were ever described as beautiful. However, once they start to win a few races, or these days get a marketing team behind them, then beauty seems to follow soon after. If you want a beautiful proa, have a look at Godiva Chocalatier, Rory Nugents proa. Newick like lines (may even have been a Newick?), sleek and minimal. I think beauty is an overrated term. I prefer elegance: of function, design and looks, in that order. regards, Rob
Subject: Re: [MHml] Catamarans and The Thomas Crown Affair From: ROB DENNEY <CARBONDESIGN_at_COMPUSERVE.COM> Date: Sun, 12 Sep 1999 04:58:08 -0400 To: multihulls list <multihulls_at_steamradio.com> Marius said >From my personal viewpoint , some proas are not ugly at all . Actually I liked the lines and the idea per se . Glad to see you are coming round. Marius asks My reservations came when I tried the mental exercise of picturing sailing one in a gale and it looked to me as if the proa snip could be a very unforgiving vessel . If anything goes wrong, you're done snip but what happens in a proa if your only ama breaks, If your only ama (windward hull for those not fluent in polynesian) breaks in a proa you are just as far up the creek as if your only windward hull on a cat or tri breaks. You may be marginally better off in a tri. I presume you sail a 2 ruddered schooner so that you have some redundancy when a mast or rudder breaks? No, you ensure they are engineered correctly, test them before going offshore and then keep an eye on them. Same applies to proas. Marius says you are caught sliding backwards on a breaking wave and the wind on the wrong side, the rudders arranements seem awkward , This is a more sensible thing to worry about, and as no one I know has done it in a Pacific proa , it may well be a problem. Cheers (Atlantic proa) did heave to with ease on both Atlantic crossings. However, I suspect it is of no special significance, asuming the boat is designed with this in mind. The wind on the wrong side is a rare occurence once you have mastered shunting and with a weather cocking rig and adequate bouyancy in the weather hull (a la Harry type proas) the proa will not be any worse off than a cat or tri, and much better off than a tri with small floats, or a foiler. In fact, because the rig weathercocks, the proa is better off than the cat or tri caught aback with all the sheets cleated. If the rudder arrangements are awkward, change them. 2 ruddders, working independantly, or together are much better than one. Any awkwardness comes from the connections and can be rearranged. Marius says the manoeuvering assumes you have to bring the boat to a stop . etc, I instinctively dislike the idea of being dead in the water during any manoeuver , I'd rather have steerage and maintain some speed (again , my own personal conservative view ) Stopping to tack (shunt in a proa) is a lot better than getting caught in irons on medium/big waves in your conventional boat and being blown backwards, with all the loads this puts on the rudders and steering gear. Shunting also means that you can have up tiny amounts of sail, as you do not need large amounts of boatspeed/power to push the bows through the waves and the eye of the wind. Shunting has a lot of advantages over tacking. The main one is that it can be done with little or no boatspeed and is totally controlled. This is very handy in crowded places, and in big sea, strong wind conditions. A secondary one is that most of the things that can, and do go wrong (genny caught on spreader, wrap on winch, crews hand caught in the traveller, winch handles coming out and hitting operators, or going over the side, ropes round the tiller, crew falling over while changing sides, etc) on a conventionally rigged multi while tacking, are not problems on a proa. Bringing the boat to a stop is a bonus, not a problem, except when racing. The worst part about tacking a conventional boat in big seas is finding a relatively calm patch, or at least one without breaking waves to prevent the tack. On a proa, you dump sheets, bear away, reverse the rudders (automatic if designed properly) sheet on and take off again. This process, from full boat speed to full boat speedd is as quick on a well organised proa as it is on a conventional multi. You may have speed during your conventional tack, but you don't effectively have steerage control. Once you have dumped the headsail sheet, you are committed to completing the tack, or ending up going backwards in irons. Picking up a man overboard is much easier in a boat designed to stop than one which is not, particularly in big seas/strong winds when the ability to return exactly along your path, immediately, and then go forwards or backwards a few metres under perfect control is going to make the difference between life and death. In U when I lost my hat overboard, I stopped within a boat length, reversed under perfect control and stopped with the hat directly under where I was sitting. This would be impossible in a conventional boat. Regards, Rob
Subject: [MHml] vacuum and infusion From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sun, 12 Sep 1999 17:04:00 -0400 To: multihulls list <multihulls_at_steamradio.com> Lee Vogtman asks I'm still confused as to when in the boat building process you should use the bagging process. I know of other builders who don't bag their strip-planked hull at all. Am I missing something trivial again? Bagging is used when cost is less important than weight or laminate performance. Bagging adds time and cost of consumables to provide uniform resin ratios, and void content. Careful hand layup of thin laminates will provide nearly as good a result. Thick laminates and cores should be bagged for optimum performance, but vibrating rollers, contoured cores and general overbuilding of non performance boats all provide more or les satisfactory results. There are thousands of strip planked boats in Aus and NZ. None of them are bagged. The savings of weight are just not worth the cost and drama. Lee says I still don't understand why some builders bag their stuff and others don't. Is it called for in the plans by the designer or is it the builder's call? I would think that if it's a simple process (and it looks like it is if done correctly) then everyone would want to use it. Builders bag if the customer will pay for it. They do not tend to use cheap techniques or materials (reliability being more important than cost), so it is not a cheap process. It is simple, but it always takes time, over and above that to lay up by hand. Generally it is the designers or the owner call, the builder just does what he is paid for. As a rule of thumb, I would vacuum onto a foam or honeycomb core of a performance oriented hull, but not a strip planked cedar hull, unless the laminate exceeded say, 1 kg per sq m, (30 oz per sq yd) in which case i would do it in two hits rather than mess about sealing the mould for vacuuming. High performance fibres like kevlar and carbon should be vacuumed to make the most of their propertiess. Uneven resin concentrations make for nasty stress concentrations. Carbon looks the same wet out or dry, so unless it is vacuumed, it is difficult to know when it is wet out properly. Tom Speer says With all the discussion about vacuum bagging hulls, anyone want to chime in with their experience in doing resin infusion? As I understand it, this modern technique is very much like bagging a wet layup, except that you lay up all the plies dry. Then the bag goes on, and when vacuum is applied to the top, it sucks the resin up from the bottom. Much less excess resin because when the resin fills an area, hydrostatic pressure stops more from coming in. This technique would seem to require litte more than vacuum bagging, cut down on waste, and take all the panic out of trying to lay up, bag and consolidate before the resin goes off. Resin infusion was originally done on matched moulds. One either side of the laminate and the resin pumped and/or sucked in. Jeremy Rogers' yard in Lymington 20 something years ago did this on the OOD 34. I expect it was pretty common on smaller structures before this. It was a dubious process at best. Infusion got a boost when the EPA lowered the acceptable level of voc emissions allowable in industrial processes. Infusion contains virtually all the styrene emissions in the system. It is a bit different to straight vacuuming, as there needs to be a layer between the bag and the laminate which allows the resin to flow. You cannot suck resin very far through dry laminate alone. There are some interesting flow problems concerning areas where the resin, and the entrained air flows rapidly or slowly, depending on laminate and core thickness, type and weight. Consequently, resin is usually recycled through the laminate more than once. Once the system is sorted out, it is a low stress, very fast way of laying up a hull. During the sorting out, it is very stressful, as it is possible to lose the lot, through exotherm of the resin, reinforcement not wetting out, pump or vacuum failure. The worst that can happen with vac bagging is a leak or loss of suck, both easily fixed. You still have the cure problem, exacerbated by the potential for large quantities of resin to accumulate and exotherm. For this reason and it's viscosity, vinylester is the preferred resin system. The waste component is not much less than vag bagging, once the bugs are out of any particular moulding. Until then, it is potentially large. Tillotson Pearson (Rhode Island, i think) have patented a system known as SCRIMP, which they use on their boats. They have the bugs out and it works well, by all accounts. A licence to SCRIMP costs $10k, I think. Regards, Rob
Subject: Re: [MHml] Catamarans and The Thomas Crown Affair From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Mon, 13 Sep 1999 17:12:14 -0400 To: multihulls list <multihulls_at_steamradio.com> Graham A says I have no desire to Stop,Reverse and turn through 270 degrees every time I want to tack or jibe. Fair enough,(apart from the 270, which should be 90) but you should appreciate that unlike conventional boats, you don't actually have to move at all. None of this scrambling from side to side stuff is required. You sit there, to windward, bear away, dump the sheet, change tillers, turn your head through 90 degrees, pull in the other sheet and off you go. All perfectly controlled, no heads banging on boom, no sheets flailing or sails flapping, and with a balanced rig, no big loads. In fact on small to medium sized proa, the sheet won't even need a purchase, much less a winch. Imagine trying to market your car if you had to change ides every time you turned a corner! Gybing is a similar exercise, but instead of bearing away, you luff up. Neither of these is as efficient on a race course as tacking or gybing a conventional rig, unless your proa is kite powered. However, shunting does have numerous advantages as per my last post. Accidentally gybing or luffing through the eye of the wind are a nuisance, the same as on a conventional boat. On a well set up proa it is no huge task to sail out of either situation. Accidental gybing is quite rare as if the proa is light enough (and they should be) then it is faster to sail a series of broad reaches downwind. Hope this helps with your ejumacation. Good to see you have a sense of humour. This and your Big Pond address imply that you are in Australia? If so, and you are ever in Brisbane, let me know and come for a sail on harry. This will complete your lesson, and may even convert you. Regards, Rob Denney.
Subject: Re: [MHml] Russ Brown tri From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Tue, 14 Sep 1999 06:23:22 -0400 To: multihulls list <multihulls_at_steamradio.com> John Gerlach says, It makes perfect sense if Russ is thinking about crossing oceans as, unless his thoughts have changed, he has stated in past interviews that he does not recommend Pacific proas for long ocean passages. Did he say why? Any idea where I can read the interview? Regards, Rob
Subject: [MHml] Re: Bagging From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Tue, 14 Sep 1999 06:23:37 -0400 To: multihulls list <multihulls_at_steamradio.com> Malcolm Phillips asks I am somewhat confused about vacuum bagging because I think there are several different techniques used to achieve different objectives. I am about to bag (if necessary) a experimental model wing sail (2m x 50cm) with one layer of 4oz cloth(??), but I wonder if it is necessary. Not only not necessary, but you will almost certainly remove too much resin, leaving the laminate starved. careful squeegeeing will give the best result. malcolm 1). When you want to achieve the lowest weight by getting rid of the unnecessary epoxy (or when using carbon or kevlar and you want the fibers straight for maximum strength) you use: >> >>Vacuum bag, core, fibres + resin, peel-ply, bleeder cloth, vacuum bag.<< Correct, but this only puts laminate on one side of the core. There is nothing inherent in vac bagging which keeps the fibres straight. In fact, if they are on the outside of a curve, they are likely to be crimped as they are compacted. Questions: Q I assume that perforated release fabric is the same thing as peel-ply and peel-ply is a trade name? A Peel ply is a material similar to spinnaker cloth, but more porous. It is actually polyester, to which the resin doesn't stick well, and as the laminate is rigid, it is easily peeled from the surface. However the bleeder cloth, even when full of resin, is fairly floppy and sticks to the peel ply, making it very difficult to remove. For this reason, a layer of perforated plastic is used between the peel ply and the bleeder. Unless a peel ply surface is required, the peel ply can be left out. A peel ply surface is a little bit rough and can be secondary bonded with no further preperation. A per plastic surface will be shiny, and needs sanding to remove the gloss before sec bonding. Q Do you ever use bleeder cloth without peel-ply - I assume it will stick to your piece? A Like the proverbial to a blanket. Q Can you use bubble wrap for the bleeder cloth - it will not absorb the resin? A Yes, but resin absorption is a big part of why you vac bag Q How smooth is the surface - after you sand off the studs? A Quite. Ready for high build epoxy. Q Peel-ply is quite expensive ($3 m2??), can you re-use it? A Not once it has resin in it. 2). When you want uniform surface clamping pressure for veneers or heavy cloth you use: >> >>Vacuum bag, core, fibres + resin, vacuum bag.<< Q This is pretty obvious. You may use bleeder cloth, rope, or bubble wrap to distribute the vacuum uniformly. I assume this would be around the edges of the surface not over the surface?? A For veneers, it must go over the surface, otherwise only the edges stick. In fact, they will tend to force a hughe void in the middle. For heavy laminate, it i important that there is a passage for the air from all over the surface. The laminate alone may not provide this passage. Q Sometimes a sheet of stiffly-flexible mylar (0.14 mil??) is put between the fiber cloth and the vacuum bag to give a smooth surface?? A This works well, as it releases easily, but it does not remove excess resin. 3). When applying light cloth you do not need the vacuum, just squeegee the excess resin off the cloth. Questions: Q Which of these three method gives the smoothest surface? A The mylar Q What else do you do to get a smooth surface? A Sand, fill, sand, high build, sand. Bloody horrible work. Unless a smooth surface is required for performance, much better to leave it rough! Q What is gel coat? A gel cot is polyester resin with pigment and thixotropic agents added. It i the coloured surface on most fibreglas boats. Epoxy gel coat is also available, but breaks down in the sun too quickly to be used outdoors. 4). When you have a negative mold. (smooth surfaced, air-tight - this may be a flat surface for bulkheads) you use: >> >> Mold, fibres + resin, core, vacuum bag.<< (Or if you want the highest fiber/resin ratio do it in two steps??) This gives a surface as smooth as the mold and should require no further finishing work. Gel coats and paint can be applied to the mold. A mold release wax is applied to the mold to stop the epoxy from sticking to it. A Again, this only puts fibres on one side of the core. Better (may be tricky on a complex shape, but easy on a flat mould) to put both ides of the laminate on at once. To do this, you need to make small holes in the core at about 50mm (2") gaps to let the excess resin and air out. A board with a bunch of nails protruding from it does a good job. If 2 mould surfaces are wanted, then doing it in 2 hits is valid, but getting the air/excess resin through the core and the cured laminate must still be done. Mould release waxes are very hard work. There are now water based liquids which are just wiped on the mould. Much easier, and a better release. Airtech Carson, Cal, make an excellent one. Two applications to bare chipboard and you get a perfect release. Hope this helps, Regards, Rob FWIW, the Betwaites are gifted, but not amateurs. they are very successful boat builders. The 18' skiffs have traditionally been sponsored for large sums of money, although only recently has there been enough left over to pay the crews. If this sort of money had gone into multihull development, the gap between monos and multis would be even larger.
Subject: [MHml] Baby Stay From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 22 Sep 1999 04:41:22 -0400 To: multihulls list <multihulls_at_steamradio.com> Jeff Russell says I've become exceptionally frustrated with the baby stay (inner, lower forward stay) on our Iroquois catamaran. I want to remove it, but thought I'd check and see if anyone knew if it was put there for some true purpose other than screwing up our tacks! <g> The baby stay is to stop the mast inverting when the main is reefed, and to stop the middle section pumping in a seaway. Check the baby stay tension (and the mast bend) for both these conditions, and if neither is affected, ditch the stay. I did on my Iroquois and cruised many miles without it. If it is needed, make a roller from 50 mm (2") pvc pipe with plugs in each end to help it roll, or put a removable connection or block and tackle on the base and only use it when conditions warrant it. Better still, throw the lot away and use an unstayed mast! This is also the solution to all the stretching spectra problems (grin). For a look at what can be achieved check out KRAZY K-YOTE TWO in the latest Seahorse or on "" http://www.yachtphoto.com/currentevents.html regards, Rob
Subject: [MHml] Inner forestay From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 22 Sep 1999 17:08:30 -0400 To: multihulls list <multihulls_at_steamradio.com> Another possibility is to use the spinnaker pole topping lift, lead to the base of the forestay in conditions that warrant it. The much bigger staying angle means that wire is not necessary. As it will only be used in suitable conditions, the impingement on foredeck space should be acceptable. There will probably be a smaller headsail up, so tacking won't be too difficult. Of course, the topping lift needs to be attached somewhere near the spreaders. regards, rob
Subject: Re: [MHml] Vacuum Bagging From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Fri, 24 Sep 1999 04:56:32 -0400 To: multihulls list <multihulls_at_steamradio.com> Stan Mackdymon asks Why doesn't the epoxy or other resin stick to the carpet? How can the air get thru the bubble wrap? Isn't that solid sheet of plastic with sealed air bubbles? Between the resin and the bleeder (carpet) is a layer of perforated plastic. This lets the air and resin through, but because the holes are mall (about 1mm dia), can still be peeled off after cure. Bubble wrap is another form of bleeder, but does not absorb the resin, so is best used on cores, or timber where there is no surplus resin. The bubblewrap is between the vac bag and the laminate. I m not a big fan of bubble wrap, as it can seal against itself and leave areas of no vacuum. Hope this helps, Regards, Rob
Subject: Re: [MHml] Vacuum Bagging From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sun, 26 Sep 1999 21:40:56 -0400 To: multihulls list <multihulls_at_steamradio.com> Stan asks I'm still having a problem with the bubble wrap. Since the bubble wrap has no holes, once it gets drawn up against the carpet, thats the end of the vaccum. How does the excess resin get sucked up once the bubble wrap covers all of the carpet's pores? Stan __________ | ________Vacuum | | _______________________________| |_________________________ __I____I_____I____I____Carpet_____I______I_______I_______I____ I = pores in carpet __________________________Bubble Wrap______________________ _____________________Laminate/Resin_________________________ If you use carpet, forget the bw. They serve the same function, except the carpet also absorbs excess resin. If you use bw only, the vac pipe goes between it and the laminate, with a healthy wrap of carpet on the end of the line in case of excess resin. regards, Rob
Subject: [MHml] Re: Proa ? From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Thu, 21 Oct 1999 06:38:03 -0400 To: multihulls list <multihulls_at_steamradio.com> Craig O'Donnell says Front-rudder steering is problematic, and so is having the boat "too symmetrical". In my experience of a 5m (16'), U, a 7m (23') and Harry, a 12m (40') proa, front steering works a treat. As responsive as back steering, but nowhere near as good as both ends steering, which is in a class of it's own. W (12m cat with single rudder and rig in the port hull) also steered very well backwards with the rudder turned through 180 degrees. Apart from difficulties in getting U (7m) to plane, I have yet to have any problems relating to too much symmetry. Craig says You have to be able to really shift the balance of CLR versus CE. Again, in my experience with the 5 and 7 m proas and W, this is not necessary. The sheet loads on the balanced rig (EasyRig, ballestron, aerorig or AeroRig) are very low (single purchase only is sufficient, and W's mast is 40' long), which implies that the centre of effort is pretty close to the mast. The spade rudders are also balanced, so the clr does not move much either. In both proas shunting is easy, and once you have a system, stuff ups/getting in irons are rare, and easier to extricate yourself from than in a conventional cat. On the 7m, I occasionally sailed with only the main, thus placing the CoE well aft. Shunting was still not difficult, although tending the sheet was! I suspect that proas which need large movements of CoE/CLR to shunt successfully have either high drag windward hulls or inefficient rigs, which are the cause of the problems. It is far easier, and results in a better boat, if the problems are fixed, than it is to mess with moving rigs, rudders and centreboards. I stress that this is supposition, I have not seen any of the boats which need to move rigs or foils to shunt succesfully. Thinking about it some more, it may be that the rigs are more problematic than the draggy weather hull. The 5m proa had a small vee section windward hull which would almost carry my weight. As I am both fat and lazy, I would tend not to move inboard during a shunt. Consequently, on breezy days, while shunting, the drag from the weather hull would be large. I suspect much larger than that of the lee hull On U, it was noticeable with the final weather hull I tested (category 2 accomadation, including bunk, in a 2m long, deep vee hull), that the wake was much more pronounced than that of the lee hull. Whether this is a function of length or drag I don't know. One of the advantages of the Easyrig is that the resultant line of force of the sails is much further for'd than a conventional centreline rig. This was particularly noticeable on a reach when the drive would be to weather of dead ahead, causing the boat to heel to windward. Given that after a shunt, a proa is reaching, this could help get it on the straight and narrow rather than pushing it sideways, and then slewing head to wind. Again, the results are based on experience, the reasons are open to interpretation. Craig The rig can't really be made to work: aside from two people who fought full size versions to a standstill in recent years, the AYRS fiddled with variations on this sail for a period of years to no good end. John Pizzey built a 7m Pacific proa (Flight) with a single genoa type sail which was shunted by reversing the sheet and tack lines. According to all reports, it worked well. Terry Travers wrote a very descriptive article on this boat which can probably be accessed through Inside Multihulls. Craig, And then there's Rob Denney's tiny test boat with the balanced rig, whatever people call it, jib and main on a single boom. This rig also worked on the larger 7m proa (U), on W and on any number of Aerorigged boats. Why it is not more popular is a mystery to me. The reasons Harry has wing sails instead of an Easyrig are: 1) The sails are expensive, as are all high performance soft sails. The wing is very cheap; about $US500 for the mast, stay, wing covering and controls . If I had thought about it, I probably would have covered them with polytarp. 2) The carbon mast for the Eayrig is expensive, as are all masts which are small and light enough to be efficient. 3) Although the sheet loads on an EasyRig are low, the halyard loads are high. These have been eliminated on the wing rig. 4) Any rig with a mast in the most critical area of air flow is inefficient. The wing rig encloses the mast. This also allows a large section, light weight, cheap materials mast. 5) The wing enables rectangular sails. Better flow from front sail to back, plus max possible sail area for given rig height and width. Whether this will outweigh the lack of high aspect elliptical plan form which is the high performance norm will be known in the fullness of time. Having said this, it should be noted that the wing rig does not work, yet. Model # embarassingly large is being tested this weekend, weather permitting. I've learnt heaps, but have yet to actually sail a wing. For those who are interested, we have spent a couple of weekends away on Harry and my wife reckons the sitting in the sun, drinking wine aspects of the boat are a resounding success, as is the accomadation. Regards, Rob
Subject: [MHml] anti capsize From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Mon, 29 Nov 1999 05:13:14 -0500 To: multihulls list <multihulls_at_steamradio.com> G'day, Lead keels on monos, masthead floats on multis and pods to leeward on Pacific proas have 2 things in common. They prevent capsize (to a greater or lesser degree) and they are weight and drag in the worst possible places. A Pacific proa with a mast canted to leeward and a reasonable sized windward hull is self righting/non capsizable without appreciable performance loss. For those who consider the loss of drive from a "preheeled" mast is too great, then it is not too difficult to make it adjustable. For those who have been following the harry saga, I have finally given up on the wing sails. I still think they are feasible, but not if I want to go sailing this summer. I have built a ply/carbon wing mast (the fifth mast for harry so far), 11.5m long, 550mm fore and aft, 200mm thick, 60 kgs with all fittings. In retrospect, it is too big fore and aft, handling will be a drama. Trailling it down to the boat certainly was. It blew sideways off the 4m long trailer 3 times, fortunately without doing any damage. New rig is everything I said it wouldn't be, which is disappointing. A windsurfer type sail, made by Gary Martin, with a wishbone boom. However, after 6 months of being ready to sail in 2 weeks, i am now ready to sail in one week. More in a weeks time! Regards, Rob
Subject: Re: [MHml] anti capsize From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Tue, 30 Nov 1999 05:21:17 -0500 To: multihulls list <multihulls_at_steamradio.com> ROB DENNEY wrote: > > ... > > A Pacific proa with a mast canted to leeward and a reasonable sized > > windward hull is self righting/non capsizable without appreciable > > performance loss. Tom Speer I don't follow this. An Atlantic proa (mast stepped on windward hull), perhaps? A Pacific proa, mast on the leeward hull, capsizing in the normal fashion. Caught aback capsize is unlikely if the rig is free to weathercock. (which Harry's now is not. This is one of the fixes that needs to happen once I am sailing) Rob > > ...I have built a ply/carbon wing mast snip Tom I can't wait to hear how you make out with it! I think that techniques and equipment for taming large wingmasts could be a big step forward. Rob There is certainly a need for these techniques, non of which I know of yet. It scares the hell out of me. At present, I have rigged a bipod so I can raise and lower it singlehanded. Depending on how easy this is will decide whether it is left up or down when I am not there. I am not looking forward to anchoring in a crowded bay. Tom What sort of shape is the sail planform? Is the clew at tack level (ala Goss's cat) or is the boom more horizontal? Do you get twist control by raising the gooseneck? Is the gooseneck attached to leading edge or trailing edge of the mast? Rob Sail has a 2300 mm long top batten 1.5m down from the head, so it is pretty roachy. The clew is midway between the tack and horizontal, so that the sheet pull is more or less horizontal. Twist control will be mainly a function of outhaul tension increasing leech and foot tension, I think. If necessary a vang can be rigged from the outer end of the boom to the foot of the mast. Gooseneck (piece of rope tied to the boom) and caught aback struts are attached to a rod glassed to the leading edge of the mast. The hounds are attached the same way. This was mainly an ease of building decision, but it has worked on previous wing masts we've built. Boom is a piece of alloy tube. Once I have some idea of the loads, mast rotation and shunting hassles, I will either build a wishbone (seems silly to have a boom on the lee side of the sail), perfect a means of swinging the boom to weather while the sail goes to lee, or have a seperate boom for each end. Sooner or later, the unwieldiness of the struts and shrouds will get to me and I will shove a carbon tube up the mast and bury the other end in the hull. Shortly after this, I will put a ballestron boom and a jib on it. Meantime, I accept all the "I told you so's" in the interest of getting it sailing. Rob: A Pacific proa with a mast canted to leeward and a reasonable sized > > windward hull is self righting/non capsizable without appreciable > > performance loss. > > John Dalziel I've noticed several people making this assumption and must say it a bit glib. Question: How many people on this list have actually sailed a proa- or any other multi for that matter- with masts canted to lee? While we're waiting for responses- my proa has the capability of canting the mast either to lee or to windward, and I normally sail with it vertical or a canted foot or so- to _windward_. And yes, I have tried it canted to leeward. Rob Every time you fly a hull in a multi, and most of the time in a mono, the rig is canted to leeward. John The main result was that as one bore off of the wind, downward pressure on the (lee) bow increased dramatically, with the foredeck some 4" closer to waterline than when the mast is vertical- this on a hull with a lot of flare. Rob Interesting, although this is noticable when hull flying any multi, but I am not sure how much it has to do with the canted rig. It also happens when not hull flying, but perhaps not as noticably as generally there is not so much breeze/speed/power, whichever of these causes the bow to dip. How much cant did you use, what sort of rig is it, and how breezy? Do you find that canting it the same amount to weather has the opposite, or any, effect? John Pizzey uses at least 10 degrees of leeward cant on his proas (single headsail rig) and they do not seem to be affected. Or are they? Terry? John The second effect is the addition of a LOT of extra weather helm when reaching. Rob I have never noticed this caused solely by flying a hull/canting the rig, except in a mono. Perhaps the weather helm is counterbalanced by the drag of the lee hull on a cat or tri? There was no noticable difference to the helm on my proas when the hull flew. John The problem with adjustable cant is that the vertical mast will provide more drive at a better L/D, and the crew is most likely to adjust it that way, and leave it there. If the boat is being driven hard the crew won't give away speed and power in order to prevent turtling in a capsize they don't plan to let happen. And if you aren't pushing hard, why not take in a reef or even two and quit worrying? Rob Dead right. This is why I don't bother with canted rigs, masthead floats, pods to leeward, ballasted keels, stretchy sheets, etc on any boat. Probably also why I have capsized twice, as well! However, for those who want the security, in a cruising Pac proa with a narrow, low, non inhabited leeward hull, I think a canted rig is the most effective and efficient. Mark and Dave snip inflatable tubes as anticapsize devices snip Rob A 500mm dia (pretty large) tube, 4m long would give 785 kgs of bouyancy. This is less than 100% of the total weight of harry (which is comparatively light) and 2 crew. The tube would need a significant amount of structure to support it when submerged. Consequently I am not sure it would be that much help. Fine on beach and day sailing proas, I guess, but limited on anything over 9m. Regards, Rob
Subject: Re: [MHml]Fw: Sydney Hobart 1998 or how much bullshit canyoustand? From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Tue, 30 Nov 1999 19:18:31 -0500 To: multihulls list <multihulls_at_steamradio.com> G'day, Sorry chaps, but you, and the media are missing the point. Offshore yacht racing (even for long coastal hops like the Hobart) is not about whether the forecast is good, bad or accurate. It is about going as fast as you can from a-b, without breaking boat or crew, both of which will low you down. The boat and crew should be capable of taking whatever is thrown at them, and when it becomes excessive, they must have a boat and equipment capable of heaving too, lying to a sea anchor (not just a storm jib with 2 strings and an anchor chain thrown over the front) or safely running off with a drogue. What this means is not better forecasting, but better boats and crews. Many of the boats and crews in the Hobart only go out of sight of land a couple of times a year. They are designed, built and optimised for racing on Sydney Harbour, in daylight, in 0-30 knots of breeze. They are designed around an absurd rule which takes little or no account of seaworthiness. To the best of my knowledge, none of the boats carried drogues or sea anchors. They wouldn't, as they aren't required by the rules. As seamanship is increasingly replaced by technology, I would bet that many of the crews were not even aware that there were other options to ploughing on regardless. I suspect that if they had hove to and gone below when the conditions exceeded the boat or crews ability, there would have been much less drama. Until people going offshore (racing or cruising) accept that they are primarily on their own against the elements, and prepare accordingly, cock ups like the Hobart (and the Guam race 5(?) years ago, and the Fastnet 10(?) years ago) will continue to happen. Blaming the weather forecasters is absurd and wrong. The weather forecasters worked on the same basis as they always have. A storm warning is for a certain mean strength of breeze, 52 knots. The quoted breeze strength is an average not a maxima, it must be increased in Force 8, at night, by 170% to get the maximum gust speed. See Allan Watts' book, Wind and Sailing Boats. If yachties learnt how forecasts work, instead of blaming the forecasters each time they appear to get it wrong, they would discover that weather forecasting, including for the Hobart, is pretty accurate. For what it's worth I've been to Hobart 7 times. In 6 of those we had gusts exceeding 50 knots, according to the wind gear. In each case (except one, where the dial hit the stops at 64 knots for about 30 seconds) I was dubious about the accuracy. The mast whipping around, the breeze increasing as it blows around the top of the mast/main, the wind speed pick up being higher than the regulation 10m above the surface and the moisture laden cold air all tend to make the gear over read compared to the forecast. The pictures of the sea during the race were pretty wild, but nowhere near Beaufort Storm Force 10 (52 knots mean wind speed, max gust speed, 88 knots, foam in great patches is blown in dense white streaks, surface of the sea takes a white appearance, large vessels heave to or run downwind). For those of you trying to stop outboards being banned, please note that, to the best of my knowledge, none of the inboards in the Hobart made the slightest difference to the loss of life, or the ability to handle the storm. What did make a difference was the total inability of the boats/crews to be sailed upwind in severe conditions. Make all engines optional, or better, ban them altogether. Learning when to stop sailing and how to sail in crowded areas and adverse conditions would do more to improve boat design and seamanship and hence the safety of yachties than any number of rules. Duff should also be aware that the comments by the CYC aided by certain well known journalists and weather forecasters were much, much more of an arse covering exercise than those of the weather bureau. Not that this is necessarily a bad thing. There was (still is) talk of ocean racing being stopped altogether if the clubs were found to be at fault, and/or liable for any damage/losses incurred. The problem is one of seamanship, including the design of the boats, rather than whether the weather was hot, or not. regards, Rob
Subject: [MHml] jet drives From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 1 Dec 1999 02:08:10 -0500 To: multihulls list <multihulls_at_steamradio.com> G'day, Some years ago, in Multihulls magazine there was a company named Wolfpak, operating out of Seattle. They produced a range of "low displacement" jet drives which could be run off an outboard power head. Results, including on a small (30'?) trimaran with electric motor and some Hawaiian charter boats looked good. Does anyone know what happened to this company, and whether the technology is sound? regards, rob
Subject: [MHml] DuraKore/balsa From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Fri, 10 Dec 1999 03:44:47 -0500 To: multihulls list <multihulls_at_steamradio.com> G'day, The finger jointed D'kore is Balteks. The non jointed is locally made in Australia, either by ATL or (as Cortec) by Pacific Boatcraft. Scarffing the pieces is pretty easy with the jig. With the (lack of) value of the Aussie dollar and the much more competitive boatbuilding materials market here, it may be worth buying it from Aus and shipping it to the States/Europe. Same applies to resin and glass, prices of both have plummetted recently. In the early days of DuraKore, we found the veneer was worth about 300 gsm (9 ounces) of uni glass on the balsa, in terms of strength and stiffness. Unless light weight balsa and thinner veneers are used, it is not worth using Durakore instead of cedar until it is at least 15mm thick. The trick with the movement is to epoxy the inside of the hull when you glass the outside. This stops the moisture causing one side to swell, and move. In areas where humidity goes up and down, this is also a good idea for cedar. There is as much bs surrounding Durakore as there is around any other building technique where there is money to be made. I strongly suggest you get a sample, lay up a sheet about 500mm x 500mm with the laminate of your choice, do the same with any other materials you are considering, weigh them, cost them, bend them (in both directions), delaminate them (peel off a corner), then attack them with a sledge hammer, both with support over the whole sample (slamming loads) and with edge support only (impact loads). Then leave the damaged bits in salt water for a while to see what effect this has. If you do all this, you will know more about your materials than from any amount of sales literature. It has been a while since I was involved, but most people who did these tests a few years ago, in Australia, built cedar strip boats. Unless you are a serious racer, there are many more cost effective ways of saving weight than the small gains made from the various hull materials. regards, rob
Subject: Re: [MHml] Open 6.5 class? From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 22 Dec 1999 16:13:49 -0500 To: multihulls list <multihulls_at_steamradio.com> G'day, Ron Badley Maybe 6.5m is too small, I can't say for sure. Has anyone ever tried to sail a purpose designed/built, small, offshore racing type multihull in storm conditions? Not really relevant, I think. They have sailed 6.5m cruising boats so it can be done. It just may be that the race boat will have to be a lot cruisier than what we are used to. This is certainly the case with the MiniTransat boats. In open competition, round the cans, they would be thrashed by the sports boats/trailer sailors. The same situation will occur with offshore capable multis, unless they are at least 9m long. Even the 60' tris optimise for inshore or offshore. The miniT boats grew from their special event. We would have to do the same, and I doubt there is sufficient interest to get it going, particularly as the first generation 6.5 multi would not be very quick. Having said this, I think it would be a wonderful class for at least the first couple of years until one type proved superior, at which stage, it would become like all the other development classes. Some other thoughts: 1) The cost of building small (or large, for that matter) multis need not be high. The cost of fitting them for ocean crossings is. Purchasing safety gear could easily exceed the cost of the boat. In these days of bureaucratic control, this is unavoidable. 2) Carbon masts are a safety feature, due to decreased weight aloft. Amateur built, unstayed carbon masts are cheaper than tapered alloy sticks and rigging. The amount of carbon which could be usefully employed in a 6.5m multi (mast, beams, foils) is not going to make a huge dent in the budget. A kevlar inner skin below the waterline is an excellent way of maintaining watertight integrity after hitting things. 3) Given that the aim of the class is development, and that the easiest way to make a multi faster is to reduce it's weight, it seems counter productive to have an overall weight limit. Maybe better to have a minimum skin weight, say that of 6mm (1/4") cedar with 200 gsm (6 oz) glass each side. Easily checked by taking a 25 mm dia core sample from the topsides of the winner, and/or a stat dec from the builder. This may move the emphasis away from long outrigger tris, which are surely the most expensive boats possible for their length. 4) On the same point. An overall weight limit encourages tricks such as building light (and expensive) and adding weight along the keel, to reduce pitching. It also means boats have to be weighed before (and maybe after) each race. 5) Race boats without sufficient downwind sail area (not necessarily spinnakers/screechers, but certainly something) are very boring. 6) Throw in some type of self righting capability to make designers think. While self righting becomes less of a problem as multis get bigger, at 6.5m, it is a necessity. This is a better option than minimum righting moment, which only serves to delay the inevitable. However, minimum RM may be a fairer option than sail area and beam limits. 7) Not taking advantage of developments in sail cloth and rope technology is silly. Maybe impose a cloth weight lower limit for sails so that they last, or a limit on the number of new sails, but dacron instead of kevlar/mylar/spectra is retrogressive, and over a couple of seasons, probably no cheaper. Ditto for rope. Polyester ropes mean wire halyards and shrouds. Neither cheap, nor light. 8) Extending the length limit takes us into areas which are already covered by a mulitude of boats and classes. 9) Keep designers, sailmakers, mast makers, material suppliers and others with a vested interest in selling complexity at arms length while the rules are established. Regards, Rob For those interested in Harry: It now has an EasyRig. I eventually realised that straying from what was proven to work on the prototype was foolish. Carbon mast (built in 3 pieces due to workshop and mould restrictions) with single shroud to weather and all timber boom (heavier than possible, but an interesting, and cheap, experiment). Mast and boom added $AUS1,300 ($US830), plus a jib to the budget, and meant some worryingly rough work installing the lower bearing through a very small hole in the deck. Could be sailing in January. 9.5 months for a 3 month boat is pretty grim, even by my lax standards.
Subject: Re: [MHml] Open 6.5 class? From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Wed, 22 Dec 1999 16:13:49 -0500 To: multihulls list <multihulls_at_steamradio.com> G'day, Ron Badley Maybe 6.5m is too small, I can't say for sure. Has anyone ever tried to sail a purpose designed/built, small, offshore racing type multihull in storm conditions? Not really relevant, I think. They have sailed 6.5m cruising boats so it can be done. It just may be that the race boat will have to be a lot cruisier than what we are used to. This is certainly the case with the MiniTransat boats. In open competition, round the cans, they would be thrashed by the sports boats/trailer sailors. The same situation will occur with offshore capable multis, unless they are at least 9m long. Even the 60' tris optimise for inshore or offshore. The miniT boats grew from their special event. We would have to do the same, and I doubt there is sufficient interest to get it going, particularly as the first generation 6.5 multi would not be very quick. Having said this, I think it would be a wonderful class for at least the first couple of years until one type proved superior, at which stage, it would become like all the other development classes. Some other thoughts: 1) The cost of building small (or large, for that matter) multis need not be high. The cost of fitting them for ocean crossings is. Purchasing safety gear could easily exceed the cost of the boat. In these days of bureaucratic control, this is unavoidable. 2) Carbon masts are a safety feature, due to decreased weight aloft. Amateur built, unstayed carbon masts are cheaper than tapered alloy sticks and rigging. The amount of carbon which could be usefully employed in a 6.5m multi (mast, beams, foils) is not going to make a huge dent in the budget. A kevlar inner skin below the waterline is an excellent way of maintaining watertight integrity after hitting things. 3) Given that the aim of the class is development, and that the easiest way to make a multi faster is to reduce it's weight, it seems counter productive to have an overall weight limit. Maybe better to have a minimum skin weight, say that of 6mm (1/4") cedar with 200 gsm (6 oz) glass each side. Easily checked by taking a 25 mm dia core sample from the topsides of the winner, and/or a stat dec from the builder. This may move the emphasis away from long outrigger tris, which are surely the most expensive boats possible for their length. 4) On the same point. An overall weight limit encourages tricks such as building light (and expensive) and adding weight along the keel, to reduce pitching. It also means boats have to be weighed before (and maybe after) each race. 5) Race boats without sufficient downwind sail area (not necessarily spinnakers/screechers, but certainly something) are very boring. 6) Throw in some type of self righting capability to make designers think. While self righting becomes less of a problem as multis get bigger, at 6.5m, it is a necessity. This is a better option than minimum righting moment, which only serves to delay the inevitable. However, minimum RM may be a fairer option than sail area and beam limits. 7) Not taking advantage of developments in sail cloth and rope technology is silly. Maybe impose a cloth weight lower limit for sails so that they last, or a limit on the number of new sails, but dacron instead of kevlar/mylar/spectra is retrogressive, and over a couple of seasons, probably no cheaper. Ditto for rope. Polyester ropes mean wire halyards and shrouds. Neither cheap, nor light. 8) Extending the length limit takes us into areas which are already covered by a mulitude of boats and classes. 9) Keep designers, sailmakers, mast makers, material suppliers and others with a vested interest in selling complexity at arms length while the rules are established. Regards, Rob For those interested in Harry: It now has an EasyRig. I eventually realised that straying from what was proven to work on the prototype was foolish. Carbon mast (built in 3 pieces due to workshop and mould restrictions) with single shroud to weather and all timber boom (heavier than possible, but an interesting, and cheap, experiment). Mast and boom added $AUS1,300 ($US830), plus a jib to the budget, and meant some worryingly rough work installing the lower bearing through a very small hole in the deck. Could be sailing in January. 9.5 months for a 3 month boat is pretty grim, even by my lax standards.
Subject: [MHml] Harry From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sun, 13 Feb 2000 06:53:03 -0500 To: multihulls list <multihulls_at_steamradio.com> G'day, Finally went sailing on Harry (12m Pacific proa, 650 kgs, accomadation in the weather hull, EasyRig). Single handed, with a lot of tools and junk in one of the double berths. 5 knots breeze to start with, 10 knots toward the end, flat water. Used an old jib which was half the size it should be. The main is about 20% bigger (mostly roach, the top of the sail is 1m wide) than was envisaged originally, as it was made for a wing mast when Harry was (briefly) a prototype for a proa for The Race. No instruments and no other boats to compare with, so no idea of speed. Seemed quick, as all boats do on their own. The good news is that shunting was simple and effortless, even with the wrong size sails. An indication of how wrong, is that in 10 knots, even with a 2:1 mainsheet, it was difficult to hold the sheet. With the new full size jib (Gary Martin, same as the main), it will be considerably easier. Shunting with a steering wheel and a balanced rig is a doddle. Release the (endless, so it self tails) sheet, steer onto a reach, pull in the new sheet and reverse the rudders. I deliberately put the boat head to wind as traditional proa types assured me it was impossible to get out of irons (Irons of Death!, according to one of them) with the heavy, short (7.5m) hull to weather. Reversed the rudders, sailed backwards to about 45 degrees to the breeze, sheeted on, straightened the rudders and off we went. Far easier than backing jibs etc on conventional multis. Next step is to clean up all the temporary items (almost everything!), go racing and see what breaks. Will also be going cruising in the near future. The cost got a bit out of control towards the end when some of my cheap and easy solutions didn't work. Instead of developing them, I bought stuff off the shelf. These will be replaced as time and ideas permit. Reckon I have spent less than $Aus9k ($US5,500) including a _lot_ of stuff ups and experiments. Pictures and article will be in Mulihulls Magazine and Inside Multihulls. Mk 2 is on the drawing board. Roomier weather hull, more elegant beams and lee hull, lighter, simpler to build (250 hours to sailaway), one piece carbon mast and professionally engineered instead of my guess and by god technique. Regards, Rob.
Subject: [MHml] Proas, mistake or misspelling From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sun, 13 Feb 2000 06:53:19 -0500 To: multihulls list <multihulls_at_steamradio.com> Hi Michael ! > > Claus, I am surprised that you would quote Denney from this conversation. > > Did he realize that you had your tape recorder on? Not at all - I'd never do that ! Maybe I used the wrong words or placement in my article, maybe it's just a "Transatlantic" misunderstanding. snip It is a completely wrong to believe I illegally recorded any personal talks between Denney and Zeemann. It was Rob, who reported his personal impressions before a limited audience, which is what we do here, no ? Claus G'day, Sorry for the delay, been in NZ watching the AC and sorting out W, which now works quite well, may even go racing in the near future. The free to pitch hulls are amazingly comfortable. So far nothing has broken in up to 30 knot breezes. Also got Harry sailing, at last. Re Mr Zeeman. I can't remember what I said about him, but it probably was not very complimentary as he messed me about. Did give me the opportunity to meet the remarkable Dr Martin Mai and have a look at his very carefully thought out boats though, so it wasn't all bad. Martin was ready to "stop messing about with plans and prototypes and start making some money producing boats in either Turkey or North Africa". Guess he is still messing about. Ernst Zeeman is in the same category as all the other dreamers. Probably a nice enough guy, but until he has a working boat which he can compare with others, (in terms of cost, space, speed or whatever), it will be hard to take his proa designs/comments seriously. I have no problems with anything I say being repeated, publicly or privately, as long as the context is correct. I suspect that my comments in this case will not add much to the discussion, but if Claus thinks they will, he can feel free to publish. Regards, Rob
Subject: [MHml] Aussie insurance From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Sun, 27 Feb 2000 01:52:22 -0500 To: multihulls list <multihulls_at_steamradio.com> "Anyone have any recommendations for multihull insurers / agents who cover not only Australian waters, but who will also insure a multihull for offshore passages?" peter Skirving, All Boat And cargo is pretty good, does lot of the Brisbane multis, apparently. Nice guy, has been known to support the local club Ph 07) 3893 0888 f 07) 3893 2042 Regards, Rob Denny
Subject: [MHml] Aerorigs From: ROB DENNEY <CARBONDESIGN_at_compuserve.com> Date: Fri, 2 Jun 2000 18:51:13 -0400 To: multihulls list <multihulls_at_steamradio.com> Joshua and Elizabeth ask Does anybody have any experience and or opinions about Aerorigs on 45 - 50 foot cats? How do they perform in heavy weather? Is the additional windage under bare poles significant? Is there an alternative to Lazy Jacks I have no experience with Aerorigs except that they are incredibly expensive and very heavy. I do have some experience with unstayed ballestron rigs on multis up to 12m (40'). The additional bare poles windage of the mast is almost certainly less than the spreaders, wires and asociated fittings on a conventional mast, particularly some of the overrigged horror shows passing as cruising rigs these days. The boom beam on to the wind would be significant, but it is low down, so probably not very. I guess it could be left free to swing head to wind if it was a problem. We did a quote for a 12m cruising cat when we were building rigs a couple of years ago. The unstayed carbon mast was the same weight for a given righting moment and sail area as the bare alloy tube in the conventional one spreader, jumpers and wires rig specified by a well known spar manufacturer. Therefore on this rig the cog would be appreciably lower, as would the all up weight. Since then, the price of high modulus carbon has plummeted. It would now be even lighter, and the finished mast, cheaper. An alternative to conventional lazy jacks is to attach them to a piece of cloth either side of the boom with a fairly stiff batten on it's top edge. This holds the sail, but keeps the lj's well inboard. The cloth acts as a cover when the sail is down. Gary Martin has got this down to a fine art. One of the many advantages of the unstayed ballestron is that sails are always hoisted head to wind, as the rig weathercocks automatically. Consequently, fouling the lazy jacks is a pretty rare occurence, particularly if they are attached at 60-75% along the boom. Battens which are adjusted from the luff also help as there is nothing protruding to catch. Pete Mcdowell They will not be as close-winded as a good sloop rig , so I suppose one should say "not quite as well, ultimately", but that does not mean that an Aerorig cannot therefore be a better compromise for *you* on *your* boat. If you don't hoist extra sail for off-the-wind (a big if imho), the Aerorig will probably be better than the conventional rig (now, somewhere I have a polar diagram comparing a 23 ft Hirondelle sloop rig against the same boat with Aerorig - the Aerorig was better until the sloop version could use its spinnaker). I disagree. There is no reason why an unstayed rig should be less close winded, and a few (less parasitic drag, lower cog, easier tuning, easier trimming when the breeze shifts or changes, faster tacking, fewer stuff ups, automatically feathering mast allowing the boat to be sailed to the gust strength, rather than the lull strength, consistent mast bend qualities which are easily matched to the sail shape) why it should be better. If you add in a small chord wing section mast (not difficult, I believe Carbospars are now selling these) and/or a mast which can rotate independantly of the boom (a little difficult), then the unstayed rig gets even better. There is absolutely no reason why extras cannot be flown, either to the weather bow, the centre of the boat or to an extension of the ballestron boom. However, on a rig which can effectively use all it's sail area on all points of sail, there are plenty of times when you wouldn't bother. Pete Vertical CoG may not move much, but overall weight of the *rig* goes up, even at 50 footer size. In smaller boats, the difference is more marked. I disagree again. Not only is the rig lighter, but if fitted to the boat originally there is a large saving in weight and cost. No deck tracks or travellers, no shrouds, rigging screws and chainplates, no winches (maybe a halyard winch on a 50'ter), no seagull striker and none of the heavy structure, backing plates and fastenings needed to support these. The smallest rig we did was for a 16' cat, similar to a Jarcat. The mast on this weighed 9 kgs, fully rigged. No idea how this compares (Ross?), but if you include the weight of deck gear as well as the mast and rigging, the unstayed mast and boom would be lighter. Pete The outstanding virtue of the Aerorig [some would say the only one! ;-) ] is its ease of use - one person can steer & trim with near enough zero hassle. As always there are other drawbacks to pay for this convenience. Those who would say "the only one" and smile superciliously have obviously never sailed on a well set up rig. I have a few sea miles and owned a couple of boats. I am as unlikely to revert to a wires and tension rig as to go back to monohull sailing. The only drawbacks I am aware of are 1) the cost of the Aerorig which is easily avoided (Carbospars did not invent it, and have no relevant patents that I am aware of) 2) Lightning strikes. I have been told that there are a number of gadgets to prevent this, but have yet to see any worthwhile tests. I have only heard of one carbon mast being hit so this is a pretty small problem 3) the attitudes of equipment suppliers who have a lot to lose if the trend towards complexity is reversed 4) the attitudes of people who bag innovation without trying it. Rick Anderson Don't mean to open a flame war, but where does the "not as close winded" come from? I've watched Rob Denneys rig on his proa, and can't see you'd get any closer. Harry's windward performance is still not what it will be when I make/can afford a less bendy mast, a couple more purchases for the halyards and install the lower windage weather hull and beam. Rick Again, no flame starter, but why is the "big heavy balestron" a problem? I'd suggest that Rob's balestron full length, is lighter than anyone elses alloy boom from tack to clew. Thanks, Rick, but probably not. Harry's boom weighs 35 kgs (77 lbs). It is all timber and ply and is a fair bit heavier and stiffer than it needs to be for various reasons relating to my engineering incompetence. I built a 7m (23') long carbon/ foam boom for W (40'cat) which weighed 18 kgs (41 lbs). This could be reduced to about 10 (22 lbs) using high modulus carbon and optimising the laminate and section. On both W and Harry a large box boom was desirable as bouyancy to prevent turtling in a capsize John Shuttleworth > >However the Aerorig delivers 16% less drive than a conventional rig at > >apparent wind angles of 30 degrees or less. This means a loss of tacking > >angle of 4 degrees. At 35 degrees the efficiency is the same as a > >conventional rig resulting in no loss of tacking angle. > > > >This does not change the performance of the Aerorig 52 because the > >apparent wind angle will be 35 degrees or over. This is due to the added > >weight for cruising comforts, and the lower sail area. However increasing > >the sail area and lightening the boat will not improve windward > >performance as much as expected, because as the apparent wind angle > >gets less, the efficiency of the rig decreases. My estimate is that you only > >get half the benefit. i.e. if you increase sail area by 20 % expecting an > >improvement of tacking angle of 4 degrees, you will only get an > >improvement of 2 degrees. (slight change made to punctation by me) No idea where these figures come from, or how they apply to specific boats, or for that matter, how they apply to the 52. I suspect they are the results of some wind tunnel tests undertaken by Carbospars combined with some of JS's mathematical wizardry. Again, there is no reason why an unstayed rig should produce less power. The figures may well be correct, and relevant, but I would like to see some full size proof before I would put much faith in them. We were talking specifically Aerorigs here ; I would be quite open to agree Rob Denney's balestron rig could be closer than say an equivalent Aeroig (presumably in Rob's boat..... hmmm). Here I think we embark on the 'accuracy of comparisons' road again. Thank you. The rig on Harry is not unstayed. It has a single shroud to the windward hull. This means a smaller (at this stage, too small) lighter mast is needed than if there were no stays. The lack of shrouds is only one of the ballestron advantages. It's balance and ease of handling are it's major ones. These can be achieved with conventional shrouds and masts, but it beats me why anyone would bother. Accuracy of comparison can only be proven on the race course. Until I have raced a bit more, I ain't commenting on Harry's performance. Pete I would bet my last boots that a minimum weight balestron (remember it has to carry the forestay/mast/backstay & sail loads within acceptable deflection ranges) will always weight more than the same minimum weight boom even in aluminium. The conventional boom only has to carry a compression load to hold out the clew of the mainsail, and cope with the stresses caused by the mainsheet being away from the centre of loading. Ted Warren has done calcs to cofirm this (easy there, boots, relax!) Your boots are safe, although I would also add the loads when it hits the shrouds, or the wife's head, and the crash loads the conventional boom sees in a gybe. Gybing a balanced rig is a joy, most first timers want to do it again, and again, just for the jollies. Of course, if you want a mainsail that sets beyond the end of your very expensive ball bearing track, you also need to factor in vang loads. Probably not worth worrying about, as the sail folds round the aft swept cap shrouds so you can't sail on a broader reach than 100 degrees anyway. A lot of booms break. Very few of them are from direct compression loadings. Pete Tut, tut, going to all that bother to get rid of draggy stays & things, & then fitting lazy jacks............... ;-) Tut, tut, I suppose you would also think the addition of a cabin was excessively draggy.............. ;-) regards, rob Denney
Subject: [MHml] Fast, cheap and spacious, was lashing strings etc.etc. From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Wed, 25 Oct 2000 18:53:54 -0400 To: multihulls mailing list <multihulls_at_steamradio.com> Dave Culp wrote: Sure there is! Build a proa... He's right. I have just finished quoting the materials list for a 12m (40') proa, being built in Utah. Materials cost came to $Aus20,000, just under $US11,000. This includes carbon mast and rudder stocks, Gary Martin sails, spectra rigging, deck hardware, LPU paint, and _all_ the materials to build the boat in cedar/glass/epoxy to sail away condition. This for a boat with a power to weight ratio not that far from a Formula 40, is easily driven (motors at 7 knots with a 5hp outboard), and has a double berth, galley, toilet, shower, dinette, standing headroom and a comfortable cockpit. This particular boat is to go on a trailer and part of the spec is that it has to be rigged and launched, singlehanded, in less than an hour, without undue stress. Alistair Wood wrote: Come on then, let's see one! We keep hearing about how great proas are, but why does no-one actually appear to be sailing them? What do you want to know? Harry is a 12m (40') proa with all the features, except trailerability, of the boat above. It has been out of the water for the last 4 months having 6 weeks worth of work done... Will be sailing again this weekend. The old configuration reached and ran about as fast as Australia's top F31, but was less good upwind, due to sail shape problems. It now has a small chord wing mast and reduced windage. I will let you know how it performs. FWIW, Harry was sailing for $Aus9,000 ($US5k, 3.3k sterling) and weighs 650 kgs (1330 lbs). Rough, as befits an experimental boat, but sailable. Good enough for weekend cruises. Puts the $Aus50k carbon wing mast rip off into perspective a bit. With this kind of money, a proa could be built which would beat anything else out there, and still have accomodation suitable for the family. Not that this is likely to happen very soon, when the average multihull owners definition of radical design is a two tone paint job. This last sentence is the answer to Alistair's question. Compared to a cat or a tri, a Pacific proa can have higher righting moment, less windage and a lighter structure. At some time in the near future, a racing owner with a few bucks will realise this, and shortly after, cats and tris are going to look awfully heavy, cumbersome, slow and expensive. John Dalziel wrote: Proa_Files list now has 92 members with, near as I can count, 18 extant proas, and members have 4 more currently under construction. The depth of proa interest has been consistently amazing. Add most of the 27 people who have paid $US20 for Harry study prints from the article in the 25th Anniversary edition of Multihulls Magazine. As far as I know, only a couple of them are on the proa list. Regards, Rob Denney
Subject: Re: [MHml] Fast, cheap and spacious, was lashing strings etc.etc. From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Thu, 26 Oct 2000 17:19:20 -0400 To: Multihulls mailing list <multihulls_at_steamradio.com> Guy wrote Lets put a little spin on this: Harry is 40' long, only 650 kg and has a power to weight approaching a formula 40, unfortunately its getting beat by a production trimaran 9' shorter, 3 times the weight. Wonder why people people buy the trimaran ? G'day, Lets be fair and spin the whole story, instead of just the bits that suit proa knocking: If you were beaten by a boat costing 10 times (at least) as much as yours, would you buy that instead of whatever you sail now? Or would you only buy it if it had less usable accomodation as well? The lack of upwind speed was caused (I think) by poorly setting sails on a novel boat in the early stages of very low budget development. It was nothing to do with the proa format. A proa built with the same budget and development time would make the tri look very ordinary. Imagine a tri without the parasitic weight and windage of one of it's floats, half it's beams, half it's middle hull and all it's standing rigging and the reinforcement and hardware required to support it. In return for the weight and windage saving, you replace the rig with a ballestron rig which allows you to shunt instead of tacking and rearrange the water foils for better steering. How could the proa not be lighter, faster and cheaper? I should add that the poorly setting sails were due to changing the rig from a stiff wing mast to a very small diameter, bendy tube mast, not to lousy sailmaking, and that 650 kgs is 1,430 lbs, not 1,330 as ln my original post. Regards, Rob
Subject: [MHml] AeroRig From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Fri, 27 Oct 2000 06:26:40 -0400 To: Multihulls mailing list <multihulls_at_steamradio.com> Steve wrote I just came across a couple of web sites with info about the AeroRig: http://www.aerorig.com/ http://www.forespar.com/catalog/systems/AeroRig/aero.htm Anyone have any experience with this or comments about it? Any idea where they stand on the price spectrum? I've requested more info from ForeSpar. I got an answer regarding price from someone at ForeSpar...about $50k for a system for my 44' cat. Makes that expensive carbon fiber mast discussed last week seem pretty cheap. Guess I won't be trying this out soon. But it is a neat idea. Rob replies I have been building and playing with AeroRigs (we call them EasyRigs, the generic term is ballestron rigs) for a few years. They are indeed a neat idea. Beats me why everyone doen't have one. 50K is a lot of money, although the standard of finish and equipment package (on the Carbospars rig, I have not dealt with Forespars) is very high. You also need to subtract all the deck gear, (dolphin striker, chain plates, standing rigging, traveller, jib tracks, winches, ropes, main bulkhead) and the beefing up and fastenings associated with it. Still a lot of money. My experience from when we were building them was that we could build one for just over half the cost of an AeroRig, without any fittings on the boom. Ours were also somewhat lighter, partly because the Carbospars guys had higher safety factors, partly because we pressure moulded (105 psi, 120 degrees C) ours, they vac bagged theirs. There are also large savings to be made by building a wood/glass boom, instead of a carbon one. Heavier, but the weight is pretty low, so it is not too bad. What I would suggest is that you a approach a local boat builder and see if he is interested in building you a rig. If you want any other info, please ask. regards, Rob
Subject: Re: [MHml] Fast, cheap and spacious From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Fri, 27 Oct 2000 06:27:21 -0400 To: Multihulls mailing list <multihulls_at_steamradio.com> G'day, Alistair wrote Forgive me, but a 40 foot proa with power to weight ratio approaching that of a Formula 40, but performance of a production F31 doesn't sound that radical. Rob Agreed. However, it is early days in the development of the proa. Although power to weight and similar numbers are only part of the story, they do indicate what could be done with equal amounts of time, money and committment. Alistair It's hard to see how a proa will keep up with a comparable cat or tri on a beat. It seems to me that having to "shunt" between tacks, the proa will stop each time and lose all momentum, compared to a cat/tri tacking normally. The proa will have to be faster through the water to equal a conventional multi to the windward mark. (Doesn't the same apply gybing downwind, but with a greater disadvantage due to higher boat speed?) A year ago, I read an article on Fiery Cross in Multihull Mag. Ross was winning races despite having to gybe upwind. Shunting is far faster than this. I can shunt Harry singlehanded in about 8 seconds. Given a normal 12m multihull 3 tack beat (the second and third because of overoptimism on the first), this is not a huge cost and is more than offset by the enormous saving of weight, wetted surface and windage on a proa. Downwind is worse, particularly if extras are being flown, but again, the losses on a 3 gybe run need to be compared to the advantages from the light weight etc. Alistair What happens if someone luffs you, or you're at the wrong end of a port/starboard confrontation? If luffed, you luff. If on port you either bear away, shunt onto the other tack, or dump one lightly loaded sheet and stop until they have passed. None of which are difficult or inherently problematic. Indeed, Harry luffed head to wind and stopped, will get going a lot faster than a conventional multi, albeit in a different direction. Harry can sail with either hull upwind, but with the skinny mast, this is not recommended in a decent breeze. See John Dalziels excellent post for how the rules and proas can get along. Alistair > > FWIW, Harry was sailing for $Aus9,000 ($US5k, 3.3k sterling) and weighs 650 > > kgs (1330 lbs). Rough, as befits an experimental boat, but sailable. Good > > enough for weekend cruises. Hardly a fair comparison here. What would be the cost of Harry, once you add in the the cost of design and build time (if you didn't have those skills), hours to produce a commercial quality of finish etc? Rob Indeed, hardly fair, but on the same basis, neither is your comment on the relative speeds above. Harry took me "about" 200 hours to build, in a 20' x 10' space with the bits assembled on a friend's front lawn. I have a reasonably detailed list of what was done each day and how long it took, for the unbelievers. "About", as towards the end there was a some wasted time with unworkable ideas which I have excluded. In Australia, a probuilder, with factory will cost $50 an hour, a very competent backyarder $20. Assuming we use the pro and that he is more careful than I am and that the finish is perfect, allow a generous 400 hours, $20,000. Plus the $20,000 for materials, $2,500 for plans and support, and a Harry would be sailing for $42,500. These are $AUS. $US22k, 15k pounds sterling. Add another $Aus1,500 for top of the range sails plus say, $Aus2,000 for safety gear and you are ready for coastal racing. Another couple of grand for a bit of comfort inside and you have a weekend cruiser. All prices ex tax and freight. Of course, you could also build a racing only version from foam/carbon and save half the weight, for the same hours, but maybe double the materials cost. Put a bigger rig and space for water ballast on it, and you would have a pretty quick little boat. Say 400 kgs (880 lbs) and 60 sq m (640 sq') An empty Bruce number of 2.6 for $aus65k Alistair In any pursuit of extreme performance, there is a rule of diminishing returns. The last bit of performance is always extortionately expensive to achieve - which is partly why F40 died out. Rob Absolutely. This is why it is good to look at other options, and take advantage of the big gains possible in the early stages of development. If you look at the performance of Harry vs the tri in the light of Harry being only 5% developed, the future for proas looks pretty bright. Alistair > > .... With this kind of money, a proa could be built which > > would beat anything else out there, and still have accomodation suitable > > for the family. Not that this is likely to happen very soon, when the > > average multihull owners definition of radical design is a two tone paint > > job. This last sentence is the answer to Alistair's question. ... and sounds like a veiled dig at someone who happens to sail on a yellow and red cat (which isn't mine)! I hope this isn't going to degenerate into a personal attack, just because I've asked a question. Oops. The two tone paint was the most disparaging tongue in cheek thing I could think of, based on a conversation with an owner about whether he was being too daring painting his hull 2 different colours. Absolutely no reference meant to Orion, it's gorgeous paint job or Harvey, all of which I admire enormously. Sorry if any offence was taken, it certainly was not intended. Alistair Most multihull owners don't want "radical" - that's what makes them the average. Rob Can't dispute this, but a lot of them are paying a lot more, for a lot less, than what they could be. And those who think they aren't average, should be investigating proas. Alistair As I said before, I'd be fascinated to see one in action, but at the moment all I've got to go on is these statements that proas are the answer, with no practical evidence and against which I have some queries. Rob You are welcome any time. Let me know flight details and I will pick you up at the airport. Or send me 10 quid and I will copy and post a (pretty poor) video. Can't do much more than this at the moment. The theoretical and numerical evidence is pretty convincing, it just needs someone with the money and energy to build a serious racing version. This probably won't be me. I keep getting involved in the next great idea, without fully developing the last one. Once I can see it will work, I move on. Would you like to hear about kite boats???? Alistair I can see the fundamental thinking behind a proa - effectively leave behind the hull of a trimaran that you're not using on a given tack, but to me there seem to be some fundamental disadvantages. In particular, the loss of momentum in manoeuvres, the lack of righting moment if caught aback (Atlantic proa), the complexity of having to raise/lower rudders at each end in each "tack", being forced into having double ended hulls, etc. Rob You leave behind more than just one hull. Also 2/3 of the main hull. Plus, the structure can be much lighter. On Harry all the water foil, beam and rig loads are taken by a 5.5m (18') length of hull 1.2m (4') high x 500mm (20") wide. This can be made enormously strong for little weight, compared to a cat or tri on which almost the entire structure sees huge loads and has to be built accordingly. The lack of momentum can be a blessing. Try changing your mind about a tack half way through it on a cat in choppy seas. Getting back to a man overboard is a 20 second job on a proa, and you stop exactly where you want to. In effect, you trade momentum for control, a far better thing to have. On Harry both rudders stay down, except when sailing downwind when the front one can be raised, or in shallow water, when they both can be. Shunting involves releasing the lightly loaded 2:1 mainsheet, turning the rudders through 180 degrees (half a turn of the wheel, automatic with tillers), and pulling in, by hand, 4 m (13') of new, lightly loaded mainsheet. Nothing else. About the same effort as merely changing sides in a conventional cat. Far less effort than dumping and sheeting in genoas, moving travellers and easing and sheeting in mainsails. If Harry is caught aback, the rig weathercocks and you sail back to where you want to be. Little or no righting moment is required. Double ended hulls are very easy to build, and for long skinny hulls have negligible effect on performance. Hulls which don't need to tack (Open 60 tri floats for example) don't need rocker , allowing higher prismatic coefficients and ultimately higher speed. Please detail the etc. Most of the old, established proa problems have been solved on Harry. Alistair I think it's great that people are out there experimenting with different types of boat. Perhaps one day the proa will be a common sight, but at the moment it appears that for most people, most of the time, the disadvantages outweigh the advantages. Rob Thanks for the encouragement. One day they will be. It is the percieved disadvantages, not the actual ones that are slowing acceptance. Hopefully, intelligent questions from people like you on forums such as this list, and my "everyone's welcome for a ride" philosophy on Harry will start to break down the barriers. Of course, one owner like Harvey would break them down a whole lot quicker! Regards, Rob
Subject: [MHml] Fast, cheap and spacious From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sat, 28 Oct 2000 04:00:25 -0400 To: Multihulls mailing list <multihulls_at_steamradio.com> Peter wrote Some idle questions about proas. Q What defines a port starboard confrontation on a proa ? A Same as on any other boat. If they are on different tacks, one is on port, the other starboard. Q How does the other guy know what is you port or starboard ? A Same as on any other boat. the opposite side to the boom. A proa rig sailing looks just like the rig on a conventional boat Q How do you fit nav lights to a proa? A With difficulty. They need to be changed each time you shunt. There is so little else to do during a shunt that this is no hardship. Q Does shunting at night confuse the hell out of everyone else? A No more than tacking does. One minute the boat is heading towards you and you see a red and a green light , the next it is heading at 90 degrees and you see a red or a green only. All pretty simple really. regards, Rob
Subject: [MHml] Endorphin From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sat, 28 Oct 2000 04:00:36 -0400 To: Multihulls mailing list <multihulls_at_steamradio.com> Roy, The delivery was hard work. The boat had been laid up afloat for a couple of years and was pretty tired. It was also overloaded. It was hard on the wind almost all the way, the crew were rookies and frequently sick, one of the rudders broke halfway through, and the front beam sheered (misaligned hulls, I think) 100 miles from Gladstone. I doubt we exceeded 10 knots all the way. In the condition it was in it would have disintegrated before hitting 20 knots. However, in New Zealand, these boats (stripped out, with big rigs) are blindingly fast and sailed like big Tornados, regularly beating much newer and bigger designs. Keep it light and you won't be disappointed. Regards, Rob I was in Sydney in 1987 and the day before we left I was in contact with a Doctor who sailed a Turissimo 10 (similar to mine). I forget his name but his boat was called "Endorphine". Lack of time prevented me from going for a sail with him but he did say that he had seen 22.3 on the clock on a reach. Are you familiar with him, or the boat ? Roy Mills ------------------------------- Yes I know Alex Burton. He sold the Turissimo 10 and now has a 40'+ bridgedeck cruising cat, also called Endorphin. Rob Denney delivered the Turissimo up the coast to Gladstone (700 N Miles) and may have an opinion. I never sailed on it but wouldn't doubt an instantaneous 22.3 and would expect steady 18's.
Subject: [MHml] Proa perspective From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sat, 28 Oct 2000 04:01:29 -0400 To: Multihulls mailing list <multihulls_at_steamradio.com> Al > > If you were beaten by a boat costing 10 times (at least) as much as yours, > > would you buy that instead of whatever you sail now? Or would you only buy > > it if it had less usable accomodation as well? A professionally developed, built and marketed proa would not cost 10% of a Farrier F31. Let's compare like with like. Rob Sure, as long as we are consistent. Giving me a hard time for being slow, and also for being cheap is a bit rich. If it helps, look at Harry as a cheap, but not excessively so, 25' roomaran (2 doubles, toilet and galley, etc), which has a tiny other hull of only 22 sq m (230 sq') surface area but which is almost as fast as that well sorted out, well sailed, highly optimised, very expensive 31' tri, which lost it's rig last weekend. $12,500 to replace it, in alloy. I have been thinking about the F31 and Harry. Harry's Bruce number (an indication of power to weight), empty is 1.7, a F 40' 1.9, the trailerable Harry 1.8. According to Claas, an F 31 has a Bruce number of 1.4. He doesn't say under what load conditions. Because harry is so light, the addition of 2 crew, outboard, anchor, 100 kgs of tools, etc lowers the Bruce number far more than the same weight does on the tri, or the F 40. Does this make my statement about Harry having a power to weight ratio approaching an F40's incorrect? Probably, although inadvertently. Sorry for misleading you. Al There are plenty of people who've designed and built their own cats and tris - how does your budget compare to them and their performance/accommodation? Rob No idea. Give me an example and I will compare. See my last posting for my prof built numbers. If they have spent less than me to get a boat with Harry's accomodation and performance, good for them. Al > > A proa built with the same budget and development time would make the tri > > look very ordinary. Here we go with the blanket performance statements again. From my experience, most production multihulls are slower than the one-off versions, as they are inevitably aimed at the mass-market, with heavier build for longevity/resilience, more equipment, "plusher" furnishings etc. Rob How can it be anything other than blanket statements and generalizations until someone actually does it? What specific evidence do you want that proas can be cheaper, lighter and faster. If you want cold hard facts, based on an actual boat, you will have to build one. Al > > Imagine a tri without the parasitic weight and windage > > of one of it's floats, half it's beams, half it's middle hull What is the cost of eliminating one hull of a tri? Reduced safety in extremes? Rob No more reduction in safety from less beam than on a cat of the same weight. In fact, the beams on a proa are less loaded than on a tri, therefore for the same beam weight, it can be wider. In fact, as it doesn't have to tack, the beam can be considerably more than either a cat or a tri. However, rather than do this on a racing proa, I would use water ballast. This is a big plus as it is always to windward, so doesn't need to be tacked, and can be easily dumped, on either tack. Al How much way do you lose while shunting, compared to a trimaran tacking - enough to cause a worry if trying to clear a rough lee shore? Rob You lose all way when shunting. As I said, I can shunt in 8 seconds, singlehanded. If Ross is reading this, how long does he take to tack Mollyhawk, singlehanded, or a full genoa F31?. Tris are easier. How long does it take to tack XL2 singlehanded, Paul? Also, how long does it take to get back to a man overboard? And of course, how knackered are you after these exercises? How often do you do more than 3 tacks per beat? Al If you remove half the middle hull, surely you lose half the accommodation? Rob The half you remove contains the unused bits at the ends, the bit under the cockpit, the daggerboard bit, the mast bit and all the beefing up required for a highly stressed boat. In a cruising proa like Harry, you cantilever the cockpit (only seats, no winches or travellers) and bunks off the inside of the hull (see Multihulls mag for the layout). In a racing proa, you go as small as you can to fit the minimum race rules. Al > > ......... and all it's standing rigging and the reinforcement > > and hardware required to support it. Cats and trimarans have been built with free-standing rigs too, so that's nothing to do with proa concept. Rob Agreed, but the ballestron rig is the reason why Harry doesn't have all the problems you mention in relation to proas. Many of which, I agree are problems for most proas. Al > > In return for the weight and windage saving, you replace the rig with a > > ballestron rig which allows you to shunt instead of tacking... At present, I can only see having to shunt as a disadvantage. Can you enlighten me? Rob It is a loss when racing in flat water against fully crewed boats. The time lost is negligible, but the distance gained shooting directly into the breeze during a tack on a tri or mono is significant. My argument is that this is outweighed by the proa advantages. Shunting is pretty idiot proof. Almost nothing to foul or snag, no flogging sheets to come undone under load, no risk of getting in irons if the helmsman slips or a big wave hits at the wrong time, no winch over rides, no missed runners, etc etc. I could shunt directly upwind between 2 marina arms if I wanted to. Wouldn't be fast, but it would be controlled. Try this, singlehanded in Orion, much less a 40 footer. I think that as with so many new ideas, we should look at it the other way round. If everyone sailed ballestron rigged proas, and you came along with a boat that had twice as much surface area, almost all of which was hugely stressed, heavy and expensive, and that required 3 people to tack it efficiently, using thousands of dollars worth of gear, huge amounts of energy and a serious likelihood of injury, for a possible gain of a boatlength per beat if everything worked well, you would have trouble selling the concept. Al > > .... and rearrange the water foils for better steering. Why would you have better steering with hulls compromised by having to go both directions and foils which have to perform as rudder one moment and daggerboard the next? Rob The better steering comes from having two rudders, both relatively large. Harry turns in it's own length under motor at 6 knots boat speed. Can any other fixed, single outboard multi do this? Maneuvering in and out of marinas and tight spaces is a doddle. No steering backwards problems either. Two way hulls don't compromise steering at all. Water foils which act as both rudders and leeway resistors were the holy grail of AC racing until they discovered how difficult they were to use. The ability to fine tune the angle of attack of daggerboards has enormous potential for improving upwind speed. I only use them for steering, and have them linked, but a race crew would be tweaking them as assiduously as they tweaked the angle of incidence of the sails, particularly in close quarters upwind. Angle them slightly and climb up under that slamdunker, or squeeze out the big mother trying to roll over you. Similar effect to a trim tab. Al > > How could the proa not be lighter, > > faster and cheaper? I can see how it might be lighter. Faster? By your own admission, at present, your proa is no faster than a production trimaran 3/4s of it's size. Rob I thought we were comparing "like with like". Harry is a low cost boat in the early days of development. I guess it is at about the same stage of development as Ian's first Trailer tri. See above for why I think the F31 was faster. If my reasoning does not make sense, perhaps someone on the list has a theory why proas as a type are slower than tris? If you can see potentially lighter, what stops you seeing faster, apart from the shunting thing? Generally speaking, the requirements for speed are low wetted surface and sail area in light air, power and righting moment in heavy air. A proa (not Harry, but a 40' racer, see my last email) would have less wetted surface than any other 40 footer due to it's low weight. Sail area is restricted by the size of your wallet. Righting moment can be enormous, because water ballast is usable, whereas on a cat or tri, it is not worth pumping it back and forth. A racing proa can also be optimised to fly a hull in much less (or more) air than a cat or tri (main hull). Al Can we add "safer", which will always be a prime consideration in successfully marketing a commercial product? Rob Ahh, thought you would never ask! We can indeed. First of all, capsizing is very difficult. As the boat heels, the wind blows across the sails, reducing the capsize force. This also happens on cats, tris and monos, of course. However, where a cat or tri runs out of positive righting moment at about 45 degrees, Harry is still positive at over 70 degrees. My first proa was self righting. I believe Harry will be too, but have yet to try it. If waves do cause a capsize, the sealed mast and boom stop it going past 90 degrees. This probably would not happen with a biplane rig on a cat, and certainly doesn't on a conventional cat or tri. Passive righting occurs as the boat is blown around the mast and sails until the hulls are downwind, at which time wind action should right it. Active righting occurs by lifting the front of the boom. The rear submerges and rights the boat. Obviously, this needs some calculations for different boats, but the theory is sound, and on my little proa, so was the practise. Because the boat is light and easily driven, the rig can be smaller. Consequently, pitch pole capsizes are less likely. This is also helped by zero rocker, and the fact that length is very cheap on a proa, as the ends only have to resist water loads (similat to Goss' boat!), not rudder and forestay loads. A pitch pole capsize is catastrophic, the same as for a cat or tri. Man overboard procedures I have already covered. 20 seconds from "Man Overboard!" to sitting stationery and under control alongside the idiot is a big safety plus. The layout on Harry is such that the non sailing crew are totally seperated from the rig and sailing controls. They do not need to move, and frequently don't even notice a shunt is occurring. Compare this to the situation in the cockpit during a tack or gybe on a conventional 40 footer. Traveller whizzing back and forth, highly loaded ropes flying around, sails flapping and winches looking for fingers to jam. Ask your wife which she prefers. Harry's windward hull is called the chardonnay hull for obvious reasons. The crew is always upwind of the rig. If it breaks, they are less likely to be hurt. A well built unstayed carbon mast has very little to fail. It (effectively) won't fatigue, and does not have 50 odd little pieces of metal suffering from crevice corrosion, misalignment and general abuse. It will flex in a squall. Ballestron sails barely flap. They can be hoisted and lowered on any point of sail, with the boat stopped, or moving. A light weight boat is less likely to crush limbs during a collision with the jetty or another boat. It also needs a smaller, easier handled anchor. Unfortunately, for commercial success, we must also add conventional looks, and ideally a marketing budget. Al I've got reasonable experience of cats and tris, so understand their idiosyncrasies. However, I'm reliant on people like yourself to form an opinion of proas. I'm interested in the idea, but remain sceptical as long as no-one will address what I perceive as fundamental shortcomings. Happy to oblige. Hope I have helped with the fundamentals. If not, feel free to ask again. Best thing you could do is come over for a sail. You will more than save the cost of the flight when you build the fastest boat in the Solent for less than the cost of the next fastest boat's sail wardrobe! Regards, Rob
Subject: [MHml] areorig From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sat, 28 Oct 2000 04:01:44 -0400 To: Multihulls mailing list <multihulls_at_steamradio.com> Peter wrote I seriously investigated an aerorig (big A and small a) when deciding on our boat the cost of the rig was 3 to 4 times that of a conventional non- rotating ali mast with all standing rigging. There is also the additional cost of the supporting structure for the bearings. Rob Did you deduct the cost of all the gear you would not need? And allow for the almost zero maintenance of the unstayed carbon mast vs the replacement of your standing rigging every 5 years, and the alloy tube every ten? The wear and tear on sails rubbing against shrouds every time you sail more than 90 degrees off the breeze? The maintenance of all those critical little bits of metal, winches and tracks? The support structure is little more than a load of unis across the cabin top and bridge deck vs all the structure required to stop 10 tonnes of compression driving your stayed mast through the middle of your bridge deck, the fore beam, the bulkheads to support your shrouds and the structure to support the traveller, backstays, winches and tracks. Peter I sailed a Hirondell with one and it was the most boring rig I have ever sailed, so try before you buy. It is not bad up wind in strong winds, where you would normally be on the point of reefing a conventional sailplan, the bendyness spills wind in the gusts. Since you can't fly a spinnaker down wind this is lousy and it just does not seem to have the power when reaching compared to a conventional setup. I assume this is due to the lack of any overlap on the jib and the fact that it only comes down to a point level with the boom. Rob I have not sailed a Hirondelle, so can't comment, but it sounds like the rig was too small. Certainly making it larger would solve the problems you mention. Nothing at all to stop you flying a spinnaker, screecher, drifter or any other sail. I used an MPS on Harry today. Worked a treat. A conventional cat genoa doesn't sweep the deck upwind, much less on a reach, so I doubt the height would have made any difference. Did you also sail a conventionally rigged Hirondelle with the same sail area? Peter Have you noticed those proa guys have snuck in again. You got to give it to them they are tri..ers. Rob Certainly are. And not sneaking. Loud and proud, until it gets too frustrating then we go away and lick our wounds for awhile. Regards, Rob
Subject: [MHml] Fast, cheap and spacious From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sat, 28 Oct 2000 16:55:41 -0400 To: Multihulls mailing list <multihulls_at_steamradio.com> Pete wrote Rob & his ideas are the one thing (two things?) that give me pause as to what I am doing in building a conventional cat at GBPXXXXXX. Could someone PLEASE enlighten me as how/why you 'gybe' a proa downwind. I've asked this before but nobody seemed able to translate action into text... ;-( Curious minds want to know ('inquisitive' is the word really, but it's probably curious by a lot of people's standards too :-> ) I cannot understand - in the context of keeping the boat moving at best speed - why you would gybe downwind & thus end up with the float on the 'wrong side' in a boat that is designed to shunt ! (this of course is because I have never sailed one - see further remark about remedying this sorry situation below :-> ) Thanks for the encouragement. You gybe (shunt actually, the process is the same upwind or down) a proa downwind to change direction, particularly if you are steering at an angle to the dead down wind course to generate apparent breeze. On Harry it is easy. Luff onto a beam reach (boat rotates through 90 degrees) and dump the lightly loaded sheet , so the mainsail end of the boom swings downwind, jib end swings upwind. Pull in the new sheet so the rig has rotated through 180 degrees and the weather hull is still to windward. Bear away onto the new course. Not much effort, but not very efficient in terms of vmg. As soon as you trim the new sheet, the boat stops, then takes off in the other direction. Very smooth, but a lot of lost ground compared to gybing a spinnaker downwind. If you are also carrying a spinnaker, it gets a bit more dificult. My solution so far is to drop it and rehoist afterwards, but I am sure with a bit of experience, a better solution could be devised. Draw a sketch, or glue together a paper model if the above isn't clear. If it still isn't, send me a fax number and I will fax a sketch. No reason to gybe conventionally, although with the EAsyRig, you could run very deep by the lee. rgds Pete McD (a closet proanaut ? There is no second a! Regards, Rob
Subject: [MHml] proas From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sun, 29 Oct 2000 01:51:57 -0500 To: Multihulls mailing list <multihulls_at_steamradio.com> Guy wrote Eer actually I think not, I think the $9k gets you a pile of foam, glass, resin etc, Rob Denney might build a 40' boat from this in a few weeks, Mr. average backyard homebuilder will probably take 2+ years to build a 30'+ boat from scratch. Factor in the cost of the shed, the labour hours, travelling time, marital strife etc and I think you'll find it costs a little more. Meanwhile the chap with the tri has had a good couple of seasons sailing and has a boat with a known good resale value. Rob There is nothing special about my approach to building, except that I am rough (alright, very rough) when it comes to prototypes, and I try to minimise effort and material use (ie a lazy skinflint). Mr average builder could easily do the same, with the same approach. In fact, with the benefit of my building experience and learning from my numerous mistakes, he should be able to do it quicker. The builder of the folding version is 50 years old, never built before and is building in his garage. Be interesting to see how long he takes. On the other point you are correct. Factor in the marital strife involved in building under the house, and it becomes considerably more time consuming. The "good resale value" thing is worthy of a bit more investigation. A $90k boat bought brand new will sell for what? Say 90% of it's value after the first couple of sails, and progressively less as time goes by? This is a loss of 10%, which your accountant would consider to be pretty good. It is $9k. I could give Harry away (if I could find someone who wanted it!) and be no worse off financially than the $90k tri owner, and I have not forfeited interest, insurance, maintenance etc on $90k's worth of investment for 2 years. Guy The other spin is that Harrys hulls might not be anywhere near optimised Rob Definitely a possibility, although as a 5 hp outboard pushes it at 7 knots, with virtually no wake at any speed reached so far, I suspect the hull shapes are reasonable. The lee hull is a long semicircular tube with pinched in ends. The central 3 sheets of ply are paralell, the end ones tapered to a point, on the basis that water flows easiest along straight lines. There is no rocker, as it does not need to tack, and a high prismatic is advantageous for high speed, and nose diving prevention. The join between the end sheets and the central portion is a bit of a bump on the topsides, but fair beneath the water. The weather hull was similar, but only 3 sheets long. The new weather hull has some rocker, and seems to have less resistance. If you were racing, you would do your darndest to fly this hull in any breeze. The shape of the lee hull in particular was chosen for speed, the fact that it is incredibly simple to build was an added advantage. Any comments from you or anyone else as to the efficiency of these hull shapes is much appreciated. As I said to Al, I'd like to hear from anyone who can tell me why proas are inherently slower than tris and cats. (Dan, I accidentally deleted your comments on this. Please resend and I will respond) Guy The problem here is that the F31 development started presumably some 15+ years ago with the trailertri, the budget and sum of knowledge of hundreds of Farrier owners is vast. It is obviously unfair to compare a one off proa agaisnt such a developed product. Rob Didn't stop you in your original post. See comments to Al. I can live with you guys thinking it is slow compared to the developed product (which it is), but not with criticism of it being cheap in comparison as well. One or the other, please. Guy It does though look ordinary...... safe even for Mr. 2.2 kids to spend his $$ on. I fear the proa has one disadvantage which is purely subjective, its asymetry. Asymetry is ugly, it doesn't look "right". If your personal idea of sailing beauty is a tarpaulin hoisted on a bamboo grove this probably isn't a problem. In the commercial marketplace it is. Rob I must confess, this market stuff is not very high on my list of priorities. If Ray Krock (McDonalds man) can sell dog food and sugared water and convince everyone it tastes good, I am sure he could sell slow, ugly, cramped, expensive boats as well. The historically obvious way to do this is to introduce a rating rule. It has always done the trick for monos. It would be nice to sell some plans so I don't have to get a job to finance the kite boat, but if I sell more than a couple, I will find someone else to handle it, so I can continue playing. People can chose whatever they like, it's their money, but I think you will be surprised at how quickly speed, cheapness or spaciousness overcomes ugly. If this were not the case, there would be very few bridge deck cats under 40' sold, and they are certainly neither cheap nor fast. Guy Spin aside I'd love to see a proa developed and racing with the "conventional" multihull fleets. I'd actually like to see a proa...... Photos will be available in the next few days. I think you will be surprised at how ugly/different/assymetric/whatever, it actually is, compared to what most people percieve as beautiful/normal. As in, nothing could be that ugly/different/assymetric/whatever, surely! Fortunately, looks were never a part of the spec. I extend the same invitation to you as I did to Al and the others. Come for a sail. Better still, build a race version. Regards, Rob
Subject: Re: [MHml] Definition of tacking or shunting time From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sun, 29 Oct 2000 21:57:39 -0500 To: Multihulls mailing list <multihulls_at_steamradio.com> John wrote Specifically, I find it difficult to believe that, given a 1-ton boat moving at 10 knots, one can A: decelerate to 0, even by using the rig as a brake, B: turn the boat through 80-90 degrees at speeds near zero, and C: re-accelerate to 10 knots pointing correctly with sail trimmed, all in 8 seconds. Rob The day it was timed, there would have been maybe 12 knots of breeze, boat speed somewhat less (who can afford instruments?). Course was a tight reach. The timing was done by my passenger, I was not aware he had done it until afterwards. The 8 seconds was from releasing the sheet and slightly trimming the new sheet, which stops the boat pretty quickly, then rotating the rudders 180 degrees, half a revolution of the wheel (the longest, most strenuous part of the exercise), and trimming on the new sheet. As the load comes on, the boat tends to round up, back onto course, all sails trimmed (easy with the ballestron). Be a few more seconds before it was back up to speed, but probably less than a heavier boat with overlapping genoa. Once I sort out a few little bugs, I will be hiring a video, and may even buy a gps. More accuracy and a better idea of exactly what happens should ensue. Regards, Rob
Subject: Re: [MHml] proas From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Mon, 30 Oct 2000 20:38:56 -0500 To: Multihulls mailing list <multihulls_at_steamradio.com> Robert wrote but I am willing to forgo that luxury to buy someone else's project like Harry when Rob is done with it. How much Rob $5,000? I get a screaming deal and he does great for 2 or 3 years of sailing compared to any "expensive" new or used multi. When I am bored with it I use the "Easy rig" from it in my next project and throw the rest of the boat away. G'day, As it happens, we are moving to Perth (other side of Aus) in March 2001. I hope to come back to sail Harry in the Brisbane Gladstone, after which there are 3 scenarios. Get a bunch of mates to sail it round (5,000 odd miles, past some of the world's best scenery), sell it, or chop it in half and truck it over. Asking price is $Aus15,000, which, coincidentally is the price for a new one, with complted accomadation, a bit more strength for the Indian ocean, and kites. First to send the money, gets the boat; suspect I won't be knocked down in the rush!. Rob any info about the trailer version of Harry? How to demount, fold? How long trailer to water, estimate? How do I get a better look? Not a whole lot. There is a Harry newsletter and some pictures available on http://www.egroups.com/files/proa_file/Rob+Denney/ There is also a little bit about the folder, named Harrigami, for obvious reasons. The hinge and locking system are very simple, and pretty foolproof. It would be nice to have a quicker trailer to water time than the F boats. It will certainly be less stress as the mast is inserted horizontally, then the lee hull stood up, by rolling it off the trailer sideways. The lee hull is on a wheeled cradle, which then acts as a trailer extension. Hope this helps, but won't be surprised if it doesn't! Send a fax number and I will fax a schematic. Regards, Rob
Subject: Re: [MHml] Russell Brown in Australia From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Tue, 31 Oct 2000 16:42:47 -0500 To: Multihulls mailing list <multihulls_at_steamradio.com> G'day, Really looking forward to renewing my acquaintance with Russ. Bit embarrassing comparing boats, but comparing ideas will be fun. Actually, there is a guy in Brisbane, John Pizzey, who has been playing with proas longer than both of us. Currently lives up Bundaberg way, with house on the water's edge. I will try to find his address. Joe, no reply, so I don't know if you got my previous email offering to help, but if not, please let Russ know I wil do all I can to help him out. Regards, Rob At 8:38 PM -0500 10/30/00, Rob Denney wrote: > >As it happens, we are moving to Perth (other side of Aus) in March 2001. I > >hope to come back to sail Harry in the Brisbane Gladstone, At 9:56 PM -0800 10/30/00, Joseph Oster wrote: >From Russell: > >"Trying to find a place to leave the boat there, do you know any proa > >enthusiasts in the Brisbane , Bundaburg area? I'd like to find someplace > >besides an expensive boatyard to keep the boat. any ideas? Sounds like a deal made in Heaven, at least until March... These two guys could teach each other a *great deal* about proa design. Heck, I'd give my right arm to be a fly on the wall while they talk... (well, at least a couple of fingers. ;-) Dave Culp
Subject: [MHml] Introduction From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Tue, 9 Jan 2001 16:29:25 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> Hello, my name is Alex Mazurkewycz snip something has piqued my interest. Some time ago a poster indicated that someone was building a 40' proa in Utah. Can you guys steer me to him/her? It would be greatly appreciated. G'day, Sorry about the delay in replying. I have forwarded your request to the builder. There is some scope for you to combine your efforts and save considerable money building the rigs. FWIW, the proa being built is a trailerable version of Harry. 10.5m (35'0 long, 6m (20') wide, 35 sq m (375 sq') working sail, 650 kgs (1,430 lbs) sailing, full headroom, double bunk, galley, toilet, shower, dinette. Construction in cedar/glass. I prepared a materials list including pro built carbon mast, sails, all materials to build a boat ready to sail. Came to $Aus20k ($us11k). Construction starts in April. Meanwhile Harry is out of the water prior to being cut in three and put in a container and freighted to Perth, Western Australia, where we are moving at the end of Feb. Regards, Rob. _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Model boat competition From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Mon, 22 Jan 2001 17:15:31 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> G'day Martin, Interested to know on what you base your comment that " it being a cruiser for our waters pretty much rules out proa"? I would also be interested in the full set of rules, plus the criteria on which they will be judged. Ta. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Model boat competition From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Thu, 25 Jan 2001 02:11:28 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> G'day, Sorry Martin, your comment about proas ability to windward is incorrect. It does apply to traditional proas, but not to modern ones. A ballestron rigged proa, with connected 360 degree capable rudders, and no daggerboard (such as Harry, my 12m proa) is less effort to shunt/tack than virtually any other multi. The only exception would be a ballestron, or self tacking jib rigged tri, but even this may miss a tack and get into irons in the wrong conditions, or with insufficient room between tacks. It is impossible to get into irons on a modern proa. Regards, Rob. _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Model boat competition From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Fri, 26 Jan 2001 05:46:00 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> Rob Denney wrote: > > > > (such as Harry, my 12m proa) is less effort to shunt/tack than virtually > > any other multi. Joseph replied >> >>WRONG again dude!!! At the very least, a proa requires sheeting the main around > >>from one end of the boat to the other. Balanced rig or not, this is a string >> >>that doesn't need to be touched at all when tacking a trimaran or cat (which >> >>require only movement of the tiller). This makes the proa more complicated to >> >>tack, not less, which will surely become obvious in a radio controlled model. Give me a break. In the next sentence I said...."The only exception would be a ballestron, or self tacking jib rigged tri". These are the only cruising multihull rigs "which require only movement of the tiller" Try building a model with a conventional overlapping headsail (which still constitutes the overwhelming majority of multihull rigs) and see which is easier to tack. You could also try getting the self tacking jib rigged multi (model or full size) to tack with no way on, or in a sloppy sea/light wind situation, or from a reach. In each of these situations the ballestron rigged, 360 degree rudders, no daggerboard proa will require less effort. In all circumstances the proa will be less effort than a multi with an overlapping headsail. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] High cost of boats From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sun, 28 Jan 2001 23:02:05 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> G'day, Sure there are all the economic reasons why new boats are expensive. There are also the following, which are a lot more fundamental: 1) New boats have a flawless showroom finish. This accounts for a significant cost on a production boat, and an enormous cost on a one off. Frequently, this is the builder's choice. "This boat is an advertisment for my product". True, but it is the owner who pays for it. 2) Boat owners and consequently builders are conservative, and so are timid about trying new things. This is generally justified by the desire to _only_ lose a predictable proportion of the investment; on a new cruising boat, maybe 20% (?) in 12 months, on a race boat, probably over 50%. 3) Boats are far heavier than they could be. Thus they need more power (bigger rigs and motors) to propel them and more beam to support the rigs, bigger hulls to carry the weight, more power to push the extra weight, and so on. A large part of the weight arises from the fact that modern rigs (including the mainsheet loads) are supported from the 4 corners of the boat. Thus the entire structure needs to resist loads which are far larger than those which would be imparted by the sea alone. Balanced, unstayed rigs, mounted in the hull(s) need far less overall support. More weight is added to resist the huge twisting forces arising from two very bouyant hulls a long way apart and held together by a relatively small bridge deck. One long, lean, leeward hull to support the rig and water foils, and a short fat hull to windward to live in results in a far lighter, cheaper structure, albeit at the expense of symmetry and conventional tacking. 4) Modern rigs appear to be designed solely for the financial benefit of the fittings manufacturers, sail makers and riggers. Huge cost savings are available from simplified rigs, both in initial outlay and ongoing maintenance. 5) Gadgets. If it is posible to sail a dinghy by the feel of the breeze, it should be possible to sail a larger boat the same way. If boats are fitted out for what they are to be used for (generally weekending by 2 adults and 2.7 kids) instead of for a potential non stop trip around the world by eight adults, the level of equipment needed drops very quickly. This also applies to occasional racers, where a bit of time practising, and a bit more cleaning the bottom, generally outweighs the benefits of expensive sails, instruments and rigging. None of this is meant to imply that people who want it, should not have a showroom finish, lots of gear and gadgets, heavy boats and complex rigs. It's their hard earned money, and skin flints like me will always jump at an invitation to come for a sail. However, if lower cost is the main requirement (and I suspect it is not, in most cases), then it won't happen until the above points are addressed. Regards, Rob owner of Harry, rough finished, prototype 12m (40') proa with unstayed, balanced rig in the long low leeward hull and full headroom, 2 double berths, galley and toilet in the short, fat, windward hull. Cost me less than $Aus10k ($US5,500), ready to sail, plus a few hundred hours of productive work. _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Bagging 1 From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sun, 28 Jan 2001 23:02:18 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> I did find that the glass wrinkled on the piece of CoreCell. I think it happened because the vacuum sucking everything around into place moved the glass. Has anybody experienced this before? BTW....the guage read 23" being pulled. Is this a reasonable amount or too much? It's a Gast 1/3hp rotary vane pump. Lee G'day, Barely enough, assuming 23" is mercury, and the gauge is correct. Block the inlet to check this. It is almost impossible to get too much, unless you are using ester based resins, when sucking out the volatiles apparently becomes a problem, although it is not one I have ever come across. Enough vacuum is when you cannot hear any air being sucked in through pinholes in the bag, the seals or at any of the connections. A good reason for having a noisy pump in another room, although the hissing gets quite audible as the leaks are eliminated. You should also not be able to pull any of the bag folds off the job with thumb and finger. Try weighing the foam and cloth before you start, then again after it has cured. Resin weight left in the glass should be less than the weight of the dry glass,(ie <50/50) although this will vary depending on the weight, and hence cell size, of the foam. Look closely at the laminate. There should be no visible air bubbles. Grab a corner of the laminate in a pair of pliers and tear it off. Should be an even layer of foam stuck to the glass. The wrinkling implies lousy technique, or some extreme curves and badly cut glass, or cheap peel ply which has stretched on application and returned to shape before the vacuum was applied. Maybe too much bleeder material. For small samples with a reasonable pump (1/3 hp is reasonable) the bag should go down very quickly (and satisfyingly) with no movement. Any other questions, please ask. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] High cost of boats From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Tue, 30 Jan 2001 07:16:11 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> G'day, Dan Physics comes into play on a lot of this stuff. Unstayed rigs sound good on paper but the lever arm from stays allows for a much lighter mast section. Lighter means less material so generally less money. The most bag for the buck is still the 3 point rig with single spredders. If you don't like the cost then use technora line but get the better eyes for your splices. Rob Not just unstayed, but balanced and maybe mounted in the hull as well. Three point rigs are cheap(ish) and light, until you add all the reinforcing required to hold them up. This is not just the extra layer of glass under the chainplates, but the extra couple of layers from the forebeam all the way back to the mainsheet traveller to keep the boat from breaking, plus the larger than necessary hulls to keep them from bending, plus the large structure under the mast to take the compression loads, plus the front beam and the traveller beam. Add in the deck gear (which needs to be maintained and replaced periodically) required, plus the reinforcing this requires, and you have an expensive, heavy set up. As a bonus, once you take all this extra weight out, you need a much smaller rig. I am not suggesting that an unstayed, balanced rig to replace a 3 stayed rig on a Maine Cat or similar will automatically save you tens of thousands of dollars, (although it may save you some if you plan for it from the start). What I am saying is that until designers/builders/owners look at the points mentioned and design around them, cruising boats are going to stay expensive. Incidentally, 3 point rigs are also hopeless downwind as the main can't be eased enough. Remember, we are talking cruisers, not racers, so dead downwind is a pretty common requirement, and most wives/passengers are terrified by strong wind, short handed gybes, either deliberate or accidental. 3 point rigs are also far more work than a balanced rig, and have a much shorter life span. Dan I find multihullers as a group much more willing to try out new ideas so I fail to see that as a source of the costs. Most of the costs are from building like an air play vs building a barge. Rob There is very little difference in the construction, rigs and fitout between cruising multis and performance cruising monos. These are the areas where savings in weight and cost can be made on cruising boats. In fact, with SCRIMP (resin infusion moulding) and similar techniques, the monos which can justify the initial expense because they will be selling more boats, are probably lighter and better built. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Daggerboard construction From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Fri, 9 Feb 2001 05:41:49 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> Carbon is very poor in compression, esp as compared to its tension numbers. I've been advised again and again to run the comp calcs, as a limit to strength in carbon layups, for many applications; have experienced a number of compressive failures in carbon structures, too. Hulls, boards, you name it. There's such a incentive to make carbon skins thin, you've just got to watch your backside (literally!) Dave Culp G'day, Not quite. Carbon is very good in compression, for it's weight. This is why it is used instead of aluminium in racing and big boat masts. The problem is actually the weakness of the resin holding the carbon together. How so? There are three ways carbon structures can fail in compression. First is the way an empty beer can fails if you stand on one end, by local buckling. Masts are too long and thin walled for this to happen. Second, which applies to long, thin walled structures like masts is by the fibres being forced out of column. Same as pressing on the ends of a bunch of drinking straws. They bulge in the middle. The solution to this is adequate hoop strength. A carbon (or glass, kevlar, wood or other fibrous material) must have a layer around the inside and the outside to hold the vertical fibres in column. Wood has some of this naturally, carbon glass and kevlar depend on the strength of the resin to hold them in column. How much hoop strength is needed? When I was building carbon masts for dinghies, I spent a lot of time discussing this with some very good engineers and mathematicians. The answers were far from clear, but 5-15% of the total laminate was a popular number (guess?). How this alters if the hoop strength is placed at an angle (say 45 degrees to also resist torsion) was far too difficult for the boffins. We ended up using only the 45 deg material in and out and had no failures. Bigger masts, we wrapped in and out with 90 degree fibres. Third is an actual failure of the carbon. This is very rare, as the wall thickness to diameter ratio needs to be very high, and concrete, or metal would do the job at a much lower price. According to the local Prof of civil engineering, the published strength of carbon fibres is calculated, not tested, as it is so difficult to set up a meaningful test. I wrote an article on this and other carbon mast problems a while back. Anyone who wants a copy, let me know. End grain balsa makes better centreboard cores than foam as the bond to the balsa is generally better, as the resin is sucked down the wood fibres. This increases impact, compressive and (in thin cores) shear strength. I suspect the former is most important, as hd foam cored boards do not fail because the core is crushed, more because the laminate (or the foam from itself) has come unstuck under repeated shock loadings, and then behaves like a thin fibrous layer, buckling away from the core under compression. I saw Playstation's cores when the boards were being built. HD Nomex, very accurately shaped. Obviously, they thought the loads would be lower than on the hulls (max compressive load based on nosediving and water pressure 50' below the surface) which are alloy honeycomb, which is stronger, but much scarier in salt water. Whether they slit the board cores and put a higher density core at the base of the case or not, I don't know. If not, I bet they wish they had. Regards, Rob. _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Daggerboard construction From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sat, 10 Feb 2001 03:12:48 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> G'day, Well said, Rob (not just this bit--your whole post). Yes, I'd like to see your article. Ta. Article (and preliminary mistakes of a neophyte kite boater) sent seperately. Why do you think the high L/width ratio of masts precludes this, Rob? Alu masts suffer from local buckling all the time... <Not sure, which is why I skimmed over it. Can't find the book with the explanation (An Introduction to Composite Materials by Derek Hull ) so none the wiser. Guess that once the fibers buckling issue (and all the unexpected loads and load path issues) are resolved, the next most likely cause is local buckling. Keith Burgess of Maine Composites, who has one of the very few large presses used specifically for testing large diameter carbon mast sections to failure, suggests that local buckling is very real for carbon masts, and needs to be designed around. <Interesting. Does he test long or short lengths? If it is to do with length/wall thickness and he tests short lengths, he could be looking in the wrong place. Suspect not, though. Are his results published? > >End grain balsa makes better centreboard cores than foam I agree with all this as well; it was why I sent the earlier post RE: why were the French boats using foam? <Answer to this is simple, it weighs less. Suspect that they incorporate a shear web of higher density material, and beef it up around the case base. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Daggerboard construction From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sat, 10 Feb 2001 03:13:27 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> How about a rectangular section of some nice Sitka Spruce ?, or perhaps a laminate with an end grain balsa centre, Sitka spruce mid layers and an outer layer of some tough, springy wood such as the ash that was mentioned, or even better, hickory or hornbeam. There is a lot of high tech wood out there. Roy Mills No reason why not. For all the hassle involved in making a cored board, especially one that is used in a multitude of positions, the weight savings of a core versus a laminated wood (med density wood for the central third, long grain balsa for the leading and trailling thirds) board are not that big until the board size is very large. The wood board will be tougher, easier and more satisfying to shape, and easier to repair. For the stiffness freaks, it is easy to router a channel at max thickness and lay some carbon unis in it. regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Re: Daggerboard construction From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sun, 11 Feb 2001 06:18:07 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> I would like to use Teflon strips inside the daggerboard casing. This is a fairly soft material which would spread the load, and it would make hauling the board up easier. Problem: How do you fasten the strips in the casing? G'day, Countersunk screws, or sulphuric acid etch the teflon and glue it with epoxy. Probably both if you are going to raise the boards under load. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Re: Daggerboard construction From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Sun, 11 Feb 2001 23:08:16 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> I've not heard of this method, only of treatment with live sodium metal. How reliable is it? Would you _always_ use screws as a backup? G'day, I have not done or sen any tests, but yes, it does work. Suggest (as with all new things) that you do a test piece. Etch and glue two pieces together, then after cure try and peel them apart. If epoxy remains on both surfaces, you have a winner, probably not needing the screws. Another way would be to rebate a block of teflon, with the board hole cut out of it into the base of the case. The rebate would help a lot to hold it in place. Teflon ain't cheap, I would use UHMPWE or similar. Slightly higher coefficient of friction, but much cheaper. However, I suspect that under load, no plastic will really work in this situation. Raw Nerve (falling apart Crowther cat) had plastic rudder boxes. Perhaps Paul Nudd could tell us how they worked? Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: RE: [MHml] Daggerboard construction and carbon Mast problems From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Tue, 13 Feb 2001 05:25:09 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> Rob, Many thanks for the offer. I have a web site almost (been almost for a couple of months now) ready which has the article, with drawings and photos. I am also interested in who is asking for copies and what questions they ask, so I will continue emailing them seperately. However, you are welcome to publish it if you like. Let me know an address and I will post you a copy of the article. I don't have a scanner, so can't send it electronically. Thanks again, Regards, Rob Rob- If it would be easier for you, I can stick a copy of the article on a web site and just post the URL. The interest seems to still be trickling in... -The Other Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Daggerboard construction From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Tue, 13 Feb 2001 05:25:38 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> Some boatbuilders who use carbon in critical structural locations put the odd layer of Kevlar into the laminate at intervals. They believe that this makes the whole thing "tougher" and less prone to failure. Anyone else heard of this? Sounds right and I do it. G'day, Depends on the mode of failure. If it is bending, tension or compression, the carbon is doing all the work, so any other material is just added weight. The kevlar may hold the pieces of the broken item together, which could mean you don't get hit on the head by the mast, or that you have a broken daggerboard trying to bash it's way into the hull. Putting kevlar within a laminate to "toughen the laminate" is a waste of material. The resin will let go long before the carbon or kevlar. Examples? There is no kevlar in any carbon masts that I know of, and none in Playstations beams. Except in the damage prone areas, see below, I did not see any go into the hull. None of the AC boats have kevlar in the hulls or structures, as far as I know, ditto FI cars, except in the cockpit cell, which is non structural. Where kevlar is brilliant is as a barrier against things sticking through the hull. A laminate of 9 ounce cloth (woven, not knitted) on the inside (not the outside, as the core will support it, and it will be easily punctured or cut) will resist an incredible amount of scraping. However, finishing kevlar is a pain. As soon as it is sanded, it fuzzes, requiring a lot of work to fix. Kevlar is also very difficult to cut. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Carbon Article From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Tue, 13 Feb 2001 19:24:54 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> As there has been substantial interest in this article, I see no reason not to post it to the list provided it does not rely on enclosures (which the list software will strip) Gary G'day, Thanks Gary, but see my response to Rob. It is interesting to me to know who reads it, and what their comments are. If demand gets out of hand, I will post to the list. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Alt "RACE" boat design From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Mon, 12 Mar 2001 02:00:29 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> <Interesting idea. Here's another one: How about using the kiteship idea <with a really well designed planing hull? <Comments? <-- Matt" G'day, I'm working on it. Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Simpson Wild Shifter From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Wed, 14 Mar 2001 22:36:04 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> G'day, Andrew Simpson, half the design team is currently editor of PBO magazine in the UK. Regards, Rob -------------------- Begin Original Message -------------------- Message text written by INTERNET:multihulls_at_steamradio.com " Does anyone on the list have any experience with or knowledge of the Andrew Simpson designed Shifter, a 31' demountable trimaran built in kit form with fiberglass hull/floats in the 1970s? Any comments or leads to additional information would be greatly appreciated. Thanks." -------------------- End Original Message -------------------- _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Diesel Electric propulsion From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Wed, 14 Mar 2001 22:36:44 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> > > If you have a proa, do you have to remeber to be on > > the right tack before lowering the sails and starting > > the engine so you're pointing the correct way?" G'day, On Harry it only works in one direction. No big deal to drop the sails, start the motor and turn around. A small price to pay for all the advantages of a Pacific proa. A two way bracket is easy enough to install, but hasn't seemed worth the effort so far. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] And while I am at it From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Tue, 20 Mar 2001 01:48:12 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> "Anyone else out there with Lavac experience? G'day, Many years ago I was skipper of a charter boat with Lavac dunnies. Worked a treat until someone felt seasick. Cnumdered in the Lavac, closed it and pumped. Then felt sick agaian. Couldn't open the Lavac (vacuum sealed), couldn't control the spew. Semi digested dinner all over the place. Took me a while to clean up the mess. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Re: cost of saving weight From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Mon, 26 Mar 2001 09:23:10 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> Evan, I think you're on the right track. A pound is a pound is a pound. There are so many ways to reduce weight at very low cost or even no cost. All that is needed is a critical eye and a desire to reduce the weight. Unfortunately, this desire is far too uncommon these days, IMO. CW G'day, The toothbrush cutters are definitely on the right track. However, they are not very far down it as they are lugging around 2/3 more boat than they need to and half of it is in the wrong place half the time. Harry is a coastal cruising Pacific proa 40' (12m) long, 20' (6m) wide with 2 double bunks, full headroom, galley and toilet, plus a sheltered cockpit for 6. Built of ply and glass, it weighs, in sailing trim 650 kgs (1,430 lbs). 649.99 if the toothbrush handles are removed! It easily reaches 14 knots in 14 knots of breeze and is normally sailed (easily) singlehanded. Materials cost was $aus9,000 ($US4,500). This seems to me to be reducing weight at a negative cost, compared to most multis. Any comments? Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] OT: Searching for Glenn Rossiter of Australia From: Rob Denney <CARBONDESIGN_at_compuserve.com> Date: Tue, 3 Apr 2001 23:16:09 -0500 To: "INTERNET:multihulls_at_steamradio.com" <multihulls_at_steamradio.com> G'day, Glenn was working just south of Brisbane (Samsons Boatyard) when I left a month ago. He was about to head South for a quick trip to Sydney, then Melbourne, then back to Brisbane, and money permitting North for the winter. He will probably be in Brisbane for the Gladstone race. Contact me off line if you want his mailing address. Regards, Rob Hello all, I am searching for Glenn Rossiter of Australia the owner of the Crowther Twiggy MkII "Ark of Infinity" (perhaps also known as "Headhunter II") He is believed to be in the general area of Brisbane, Australia. Any and all help/leads/suggestions will be appreciated. Sorry for the OT post. Thanks. _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] European canal width From: Rob Denney <carbondesign_at_one.net.au> Date: Mon, 9 Apr 2001 16:31:49 +0800 To: multihulls_at_steamradio.com G'day, Been a while since I went through France, but from memory the main north south route (in at Le Havre, down the Seine to gay Paris, down the Rhone and out at Marseilles) is at least 16'. This is, or was, the main route for all the commercial barges. Canal de midi (in at Sete, out at Bordeaux) is about 16', fewer barges, lots of tourists (far more dangerous!). The nicest of them all was the Brittany canal, but it is only 13'6" wide (Iroquois cat with tyre on one side only). Far and away the best way to see France, and meet the people. Also very cheap. Whether you design a boat specifically for this, or hire one when you get there, I would strongly recommend that you spend time on the French canals. There is still a fair bit of barge traffic in Germany, so I would assume that the 16' applies there as well. Tristan Jones took a widish tri acdross Europe, so the main canals must be pretty wide. Check with the tourist departments at the embassy if you want it more exact. Also, the pommy magazines (PBO etc) are always printing articles about them, so should be able to help. Regards, Rob >Trawling the net, I was hoping to find out what is the maximum width I > >can have on a cat in order to go through the canals of much of Europe > >and the UK. Now, the best I can find is particular canals and these > >range from 14' for Leeds/Liverpool in the UK to 16' in Burgundy. Can > >anyone confirm/deny that the max looks like being 14'? Or would France > >and the continent all be 16' and it's only the UK that's 14'? Also, > >while websites are saying 14' or 16', does this mean "you'll be > >continually scraping the side of your boat" or does it mean "that will > >be comfortable and fit OK in the locks"? > > > >The obvious angle on this is that it'll limit the size of the boat > >significantly (at least the width!). Of course, if everyone who knows > >says "don't even think about the canals because ..." then I can go back > >to looking at 20' wide designs :-) while imagining not seeing inland > >Europe much at all... > > > >Thanks > >Robert (who never stops thinking that one day he might...) > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Re:possible new class, long post From: Rob Denney <carbondesign_at_one.net.au> Date: Mon, 30 Apr 2001 12:49:31 +0800 To: multihulls_at_steamradio.com, Multihull Racing <multihullracing_at_yahoogroups.com> G'day, I was recently involved in a discussion about speed sailing, and realised that no one actually knew what the fastest course racing boat would look like if only sail area was restricted . Of course, we all thought we did, but the range of "Absolutely the fastest" was large and covered _everything_ from a Bethwaite inspired planing mono with sloop rig, through to a very long triscarph, with a very tall solid wing. That prompted the following proposal for a new class. I intend to publish it as an article in any sailing magazines which will take it and then see what can be done about setting it up. But first, I would like to have it debugged by the list members. Although not necessarily Multihull content, I think we could assume that at least some, if not all, of the boats will be multis. If there is sufficient interest an alternative list would be set up. As well as comments on the viability of the class, I would be interested in variations to the rule on crew weight equalisation and the courses. Any proposed rule changes have to pass 2 tests. 1) Does it limit speed or development potential. 2) Can it be circumvented? It would particularly be of interest to hear what people think would be fastest, and what would prompt people to consider building a boat to the rule (Curiosity? Fame? 10k prize money? 20k? ). Obviously, feedback on the best way to start things rolling and future development of the class would be appreciated as well. These should be sent off list unless they have multihull content. Regards, Rob Denney Please note my new email address, carbondesign_at_one.net.au Article: First, a question: What would the fastest course racing boat look like if it was only limited by sail area? Would it be short or long? Planing or displacement? Proa, tri, cat, triscarf or mono? Hydrofoils? Canting rigs? Simple or complicated? Rigid or flexible? Fixed or movable rig? Una rig, or sloop? Solid or cloth sails? Kites? Stayed or unstayed mast? Trapeze or variable beam?.............. Incredibly, after 100 or so years of sail boat racing, this is a question without a definite answer. Boats designed by experts in the field such as Bethwaite, Cunningham, Farr, Marstrom, Murray, Naish, Ollier, or Jo Richards would, I suspect, all be different. A development class should aim to develop faster boats around the race course. Therefore, the fewer the limits, the better. All current development classes (Moths, 12, 14, 16, 18' skiffs, A, B, C class cats, Formula 40 multis, Open 60 monos and tris, America's Cuppers, The Race boats) have restrictions which determine to a large extent what the boats look like. Each of these boats would be faster, and may look vastly different if the restrictions were removed. The problem is keeping the cost reasonable. Power and weight are the 2 main drivers of boat speed. Imposing a maximum weight is one option, and would be fun to persue. However, limiting power is likely to be cheaper and easier to understand. A sail area limit would leave everything else open and would clearly establish what makes boats fast. The proposal: A single handed racing class with a limit of 14 sq m of sail area, (measured by IYRU methods for the A, B and C class cats, including spars) and a 2 handed class with sail area of 22 sq m, plus one extra sail of 22 sq m to be fastened to the boat at only three points, tack, head and clew. This would provide some down wind/light air excitement. No other rules. Sails could be hard or soft, attached to the hulls or not, of any plan shape. Hull(s) could be any number, shape, length or width. We want to know what is fastest round the cans. A fear is that solid wing rigs would take over and add expense, complexity and the requirement for 2 hulls. Maybe, maybe not. First point is that if they are superior, we want to develop them, making them cheaper, easier to handle and faster. Point two is that, interestingly, solid wing sails don't work in A class cats or any other development class. Certainly no one uses them with extras. These sail areas would provide excitement for sailor and spectator. Or maybe not. It may be that an optimized boat is a rock solid, boring, very fast boat? Sail areas are near enough the same as A cats and Tornados so these would provide a bench mark and a source of second hand rigs (particularly from the Tornado with their new rules) for initial low cost experimentation. Boats built to this rule would probably (3-4 seasons) become very similar as the limits were explored. This would be an incredibly stimulating class to be involved in during this time. They would answer most of the questions about hulls, appendages and rig shapes. They would be relatively cheap. To keep it fair, all boats would have to carry movable ballast of equivalent weight to the heaviest crew in any particular race. Not a perfect solution, but fairer than anything currently available. Anyone with a fairer solution is welcome to suggest it. Races would be mostly over Olympic courses, putting emphasis on boat handling and maneuverability, as well as boat speed. However, some races would have a speed oriented course (short beat, long reach), to liven things up and prevent course biased specialist boats from developing. Another format worth looking at would be to sail circular courses. After a few, very exciting seasons, one type would probably stand out as the best, and further development would become increasingly limited and biased towards the amount of money spent. At this stage, a one design class could be introduced for those who just want to race, fast. _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] adventures in racing From: Rob Denney <carbondesign_at_one.net.au> Date: Tue, 1 May 2001 21:56:53 +0800 To: multihulls_at_steamradio.com > > > >I understand that a certain Mr. Roberts, himself not unfamiliar with > >performance cats, prior to the regatta's start took one look at the rig and > >predicted its demise > > G'day, As far as I know, this mast originally broke in 3 places in less than 5 knots of breeze. However, it was fixed and has been hammered up and down the coast of New Zealand in a lot more than 15 knots of breeze, and been capsized. I can't help but think that either a string or 2 were missing, or that the kiwis did something different. For example, when we raced the wing masted F40, Simply the Best with masthead gear, we always underrotated the mast to keep the halyard and the mast chord in line. Regards, Rob PS Bill, I have mended and extended a few carbon masts. If I can be of any help, please ask. > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] adventures in racing From: Rob Denney <carbondesign_at_one.net.au> Date: Wed, 2 May 2001 09:59:53 +0800 To: multihulls_at_steamradio.com > > > >Rob, > >Mr. Roberts was talking about an Osborn 42, not Afterburner. Your history > >of Afterburner is correct. No strings missing, but we did have a luff > >tension problem leading us to run our small spinnaker to the mast head > >halyard, instead of it's normal halyard. In hindsight, not such a good > >idea. > >Thanks for your offer of assistance. Do you fancy a brief vacation in > >southern California? :-) G'day, I do, but can't get away until August, unfortunately, when I am coming over anyway. I can't remember whether the mast was male or female moulded, but I would suggest contacting John Hughes or Chris Mitchell to see if it is still around. If so, they could knock out a replacement piece pretty easily. Come to that, they could knock out a new mast for not much more than your repair will cost, I think. Maybe make it a bit fatter, so you can throw away some of those wires and spreaders..... If the mould is not available, I'd take a mould off the current mast (or the broken off piece, if you want to keep the taper), and build a new piece, plus an extra metre or so (4-5'). Cut the extra until it fits inside the old mast and slip the new piece over it. This assumes the hounds reinforcing is on the outside of the mast, ie that it was male moulded and is smooth inside. If not, the sleeve goes on the outside and is a whole lot uglier, although stronger, so less material will be needed. Be aware that the laminate for the sleeve may be very different to that of the extension. This is the cheap way. The expensive way has the overlap incorporated in the extension piece. Saves a bit of weight, in theory, but will cost considerably more. Regards, Rob PS, Great to see that a gorgeous boat is finally getting sailed more than twice a year, keep up the good work. _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [[MHml] core material + SSB ground] From: Rob Denney <carbondesign_at_one.net.au> Date: Mon, 7 May 2001 10:11:55 +0800 To: multihulls_at_steamradio.com > >Brian Eiland responds: > >For what its worth, and not from any personal experience, I have always had > >significant reservations about using Nidacore. Nidacore is a polypropolyene > >honeycomb onto which has been bonded a fiberglass scrim. As anyone knows it is > >virtually impossible to bond anything to polypropolyene in a truly permanent > >fashion. > > > >Its also a honeycomb stucture and therefore you are only bonding to the very > >small surface area represented by the slim edges of the material. > > > >Given that the core to skin bond is so critical in a sandwich structure, the > >two factors above make this material highly questionable in my opinion. I > >would seek out any negative uses and take a close look at their failure > >mode(s). > > G'day, The bond of the scrim to the cells is near enough impossible to break. I have never heard of it failing, or been able to induce failure, for that matter. The problem with Nidaplast is it's lousy shear modulus. Hold a thick piece between your hands and move the faces relative to each other to see how poor it is. Not recommended for structural components. The scrim also soaks up huge amounts of resin in a wet layup situation. Pity, as otherwise it is a very impressive product. regards, Rob > > > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls > > > > > >Brian Eiland > > > >www.RunningTideYachts.com > > > >____________________________________________________________________ > >Get free email and a permanent address at http://www.amexmail.com/?A=1 > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Implosion Marine Drive From: Rob Denney <carbondesign_at_one.net.au> Date: Tue, 15 May 2001 14:06:19 +0800 To: multihulls_at_steamradio.com G'day, Looks like a large scale "pop pop" or "putt-putt" boat drive to me. I called them to see if I could have a look. Spoke to Allan Burns. It is all confidential for the next 4 weeks (I will have another go then) while they do a deal with some overseas people, and won't be commercially available for at least 2 years. They have "a number" of test boats using it, successfully. Regards, Rob > >I saw a small piece in the paper today about a new steam-driven marine > >drive. As far as I can make out, steam is injected into a seawater-filled > >tunnel beneath the boat, resulting in a waterjet drive. The inventor is > >called Alan Burns, in Fremantle, and as well as an Oz-based company called > >Carnegie, a UK-based company called Pursuit Dynamics is involved. > > > >Almost all of the small amount of information I've found is financial. > >About the only description of the system is here: > >http://www.carnegiecorp.com.au/William%20Noall%20Research%20Paper.pdf > > > >Has anybody come across this? > > > >Apart from the advantages mentioned in the PDF file, it seems to me that the > >drive should be fairly light weight, and conceivably have low drag when not > >operating (minimal multi content :-) > > > >Cheers, Dave > > > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Guy Delage's proa From: Rob Denney <carbondesign_at_one.net.au> Date: Thu, 24 May 2001 11:43:11 +0800 To: multihulls_at_steamradio.com G'day, For me, proas are the least possible sail boat, of any type, for a given length or accommodation. Therefore they are the cheapest boat possible, and theoretically, the fastest boat possible. They are far less different to tris than tris are to monos, so the leap of faith required to switch is actually quite small. For the logic and the proof behind these sweeping statements, please have a look at http://www.schachtdesign.com/proafile/volume_1/U.html http://www.egroups.com/files/proa_file/Rob+Denney/ Any questions, please ask. Please note, my address on these articles is out of date. Re Russ' boats: He seldom sits to windward. His cabin is in the leeward hull. A mistake in my opinion, he would be far better off to have the accommodation in the windward hull, so he could sit on the dry side, in relative comfort. Would increase his righting moment as well. Re United Proaists: An exageration of major proportions! We are far from united on what type, rig and setup is best. Feel free to join the sometimes robust discussions on the proafile. Don't let your lack of proa knowledge stop you. There are as many thinkers as doers on this list. Regards, Rob. > >I have a question, and no disrespect is intended towards those with fewer > >hulls: What are the advantages and optimum uses for proas? I understand the > >relative advantages and disadvantages of monohulls, catamarans, and > >trimarans, but I don't have much of a sense regarding proas. > > > >I know they are reputed to be fast. The only cruising proa I am familiar > >with is Russell Brown's, but sitting out on that platform on the outrigger > >beams at high speed during a blue water crossing would not be my idea of fun > >(for an afternoon: yes). So, lets be honest now - advantages and > >disadvantages alike from the United Proaists themselves. > > > >Greg Barker > >San Luis Obispo, CA, USA > >Cross 42 Cherokee > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] advantages and optimum uses for proas? From: Rob Denney <carbondesign_at_one.net.au> Date: Mon, 28 May 2001 17:20:44 +0800 To: multihulls_at_steamradio.com > >I would imagine that a proa would be just as sensitive to problems from > >burying a leeward hull at speed as a trimaran. There must be some sort of > >trade off between avoiding that and picking up the increased righting moment. > > However, I'm with you, I would prefer to have my smaller hull to leeward and > >reef down to prevent problems in more boisterous conditions. > > > >Greg Barker G.day, Actually, not so, or at least not with a Pacific proa (rig on the leeward hull). The force that immerses a cat or tri lee hull has 2 causes. First and foremost is the heeling load, caused by having the rig upwind of the lee hull. Second is the bow down load caused by having the centre of effort of the sails a long way above the water. A Pacific proa heels (rotates) around the lee hull, thus removing this cause of hull burying. Of course, this is at the expense of the righting moment achieved by having the tri lee hull offset from the rig. On the proa this must be compensated for by having some weight in the weather hull. Not a problem, if this is where all the weight is kept anyway. For the same righting moment, a Pacific proa will have considerably less force depressing the leeward bow than will a cat or tri, I think. Anyone with numbers, diagrams or logic who thinks otherwise, please say so. Another advantage of a Pac proa is that, because there is less of it for a given length or accommodation, then the rig is smaller, so the loads are also smaller, and perhaps more importantly, lower. A final advantage is more subtle. Because they don't need to tack, Pac proas do not need hull rocker to help with maneuverability. Therefore they can have much fuller and more buoyant ends. Harry has a prismatic coefficient (measure of the fore and aft distribution of buoyancy, 1.0 indicates a cube, 0.5 2 pyramids base to base, I think?) of 0.8. This compares with maybe .65 for a full ended racing multi, and probably less than 0.6 on Cherokee. As usual, there is a drawback. The wetted surface of a high Cp hull is higher than an optimised low Cp hull. In Harry's case the weight is sufficiently low (1,430 lbs in bare boat sailing trim, maybe 1 tonne cruising) that this added drag is not significant. On Harry, the lee hull is lower (4' vs 6') and narrower (20" vs 8' overall, 24" on the waterline) than the weather hull, but much longer (40'vs 25'). Optimum uses of a proa? Anything (race, cruise or combination) you would do with a cat or tri, but at less than half the cost! Least optimium? They would make lousy houseboats. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] advantages and optimum uses for proas? Tom From: Rob Denney <carbondesign_at_one.net.au> Date: Tue, 29 May 2001 16:15:33 +0800 To: multihulls_at_steamradio.com G'day, Tom and Joseph, I agree with your logic re heeling loads and athwartship mast position, and have confirmed it with "W", a 40' cat I designed and built with the rig, rudder and centreboard in one hull. What I am unsure about, and asking for feedback on, was the forces depressing the lee bow. Unfortunately, we could not test this on W as the hulls were free to pitch independantly. I am still confused. I appreciate there is no such thing as a free lunch, but it seems that the sail loads on a cruising tri such as Greg's which doesn't fly a hull will try to depress the lee hull bow, whereas on a Pac proa they will tend to rotate it (heel). Given that it is easier to control excess heel than excess nose diving, this would be a "good thing" Maybe an analysis of Team Phillips would do the trick, or Stu Bloomfield (Crowther Design office) could explain as per Paul Nudd's comment. Would TP have more propensity to bury it's lee bow with only the windward rig up, or with only the leeward rig up? If the lee rig depresses the lee bow least, what is the quid pro quo? Assume both hulls stay waterborne, although I am not sure whether this makes a difference. regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] proa design, (was advantages and optimum uses for proas?) From: Rob Denney <carbondesign_at_one.net.au> Date: Tue, 29 May 2001 16:24:18 +0800 To: multihulls_at_steamradio.com G'day, > >I agree that the proa gives the most waterline length for a given cost. > >This leads to the "30 ft boat crammed into 60 feet" solution. So if you're > >comparing it to the rig, accommodations and payload of a 30 footer of > >comparable cost, the proa performance looks really good. If you're > >comparing against a 60 footer, the rig looks small. True, but with a pac proa, it is possible to get more for less cost/weight/building effort than on a cat or tri. If the lee hull has the rig and foils it can be as long and thin and low (except where the mast is stepped) and wet as performance dictates. If the weather hull has no rig or foils to clutter it up, and no structural requirements to support these, you can fit a lot more into a given space, aided by the fact that it is always to windward, so never sees the loads all the hulls on a cat or tri see. If the boat beam is sufficiently wide, or there is sufficient weight in the weather hull (crew, water ballast or stuff), then the rig can be as big as you like. Because the overall package is much lighter and has less air drag, the rig will be smaller for a given performance than a cat or tri. > > snip lots of interesting,correct and gratifying logic. > >That's what a cruising proa would look like to me. The weather hull would > >be larger than the traditional Pacific proa, but the center of gravity would > >be as far to windward as possible and the weather hull would be large enough > >to ensure good performance in light winds. It would cruise efficiently and > >safely when reefed so that both hulls carried equal loads, but could also be > >driven much harder if desired. > > What you have described pretty much covers harry, with a longer windward hull, and without your faith in the IMS sail model! I did consider the long windward hull, but didn't use it for the following reasons: 1) Wetted surface. My understanding is that in light air, minimising wetted surface minimises drag. A short (25') fat (24" waterline) hull will have less ws than a long skinny one. 4.3 sq m (46 sq') on Harry's windward hull, 6.3 (67 sq') on the leeward one, both carrying 500 kgs (1100 lbs). This is most important immediately after shunting. If the weather hull is not easily driven, it will act as a sea anchor and the boat will revolve around it and into irons. Low slow speed resistance has been borne out by motoring performance; 7 knots with 5 hp outboard, and increbibly easy shunting, even under mainsail only. As the breeze increases, the weather hull is lifted to a greater or lesser degree. This reduces the beam/ length ratio, thus reducing the wave drag. 2) Wracking strains. Long hulls wrack more. Resisting extra wracking loads did not seem worth the effort/cost/weight 3) Weight and cost overall: I figured the less the boat, the more the total weight and windage, and that this saving would offset any speed gains from long thin hulls. The cost of a short fat hull is certainly lower than a long thin one. Incidentally, a hull which is never pressed and has a sheltered cockpit, well inboard, does not benefit much from a knuckle. Easier to flare the hull directly from the water line, or at a small increase in wetted surface and large increase in carrying capacity, flare it from the turn of the bilge. Comments on my logic appreciated. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] advantages and optimum uses for proas? From: Rob Denney <carbondesign_at_one.net.au> Date: Tue, 29 May 2001 22:41:55 +0800 To: multihulls_at_steamradio.com G'day, Stu, thanks for all the information. Good to have you on the list for this sort of question. What is the answer? Would TP's lee hull be depressed more by the windward rig, or the leeward one when both hulls were in the water? Regards, Rob >There are a number of reasons for depressing the leeward bows of multihull craft, but the single factor that has the greatest effect seems to have been missed in the discussion so far. The ratio of the lateral stability against the longitudinal stability has IMHO the greatest effect on the pressure that is applied to the leeward bow. > > > >Boats with greater lateral stability will be able to sustain greater sail > >forces before tipping over sideways, therefore allowing more driving force > >(and counterbalacing resistance) to be transmitted into the boat and thus > >resulting in a greater pitching moment depressing the bow. This is why > >trimarans can be wider than catamarans, because three hulls have more > >loingitudinal stability than two, and the different shapes of the amas and > >main hull allow the bouyancy to be distributed further forward in the amas > >relative to the centre of gravity, which is born by the main hull when the > >boat is at rest. It is also the primary reason proas, that generally have > >relatively lower transverse stability, do not tend to depress their bows > >as much. > > > >The effect of moving the rig transversly is to move the point at which the > >downward rig force is applied, and to a lesser extent, to raise or lower > >the point of application of the horizontal component of sail forced when > >the boat is heeled. Moving the rig to leeward will move the vertical > >component of the sail force(which is resisted by bouyancy and hydrodynamic > >forces)further to leeward, therefore making a greater (or less negative) > >contribution to the overturning moment applied by the sails (moments > >produced by vertical force components about a longitudinal axis). This in > >turn will reduce the total sail force that can be carried by the platform > >and therefore reduce the driving force/resistance couple, resulting in a > >lower pitching moment and thus depressing the bows less. This effect is > >reduced to a certain degree by the reduction in the height of the center > >of pressure of the sails when the rig is further to leeward on a heeled > >boat. > > > >One other factor in rig placement is the yaw acceleration induced into the > >boat when hit by a gust or when the leeward hull is checked by wave > >impact. The further the rig is positioned to windward the greater will be > >the yawing force generated by sudden changes in sail force or hull > >resistance. If the boat is heeled then some of this yawing force will > >tend to drive the leeward bow further into the water (sideways). > > > > > >Other Factors: > > > >The overall weight of a boat will directly affect the volume of reserve > >bouyancy required to resist the pitching moment. Reserve bouyancy is > >often limited by other physical factors and therefore lighter boats are > >often capable of withstanding a greater relative pitching moment before > >"planting" that heavier boats; this is an advantage that a racing > >catamaran can have over a trimaran, which will generally be heavier all > >other things being equal. I think this may also contribute towards the > >apparently high tolerance of proas to bow depression, because they are > >generally relatively light for their hull length. > > > >I do think that a non-traditional proa that is designed with a high > >righting moment will exhibit a tendency to depress the leeward bow more > >when pressed. > > > > > >Is a proa a good race boat? > > > >Not in my opionion. I think that the relatively low transverse stability > >will prevent a proa (Pacific) from carrying as much sail power as the > >equivalent weight racing catamaran or trimaran. Also, the manouvering > >limitation of proas (shunting) will impact on their racing performance in > >any non-passage races. I think the real strength of the proa is its > >ability to sail with the majority of the weight carried by a single > >slender hull in a wide range of wind conditions, therefore allowing > >relatively high average speeds compared with other forms of multihulls > >that generally (but not always) tend to be underpowered in lighter > >conditions. > > > >My firsthand experience with proas is limited and I would welcome any > >feedback from those with more practical experience. > > > >Stuart > > > >__________________________________________________________ > >Message sent by MyMail http://www.mymail.com.au/ > > > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] advantages and optimum uses for proas? From: Rob Denney <carbondesign_at_one.net.au> Date: Wed, 30 May 2001 10:35:12 +0800 To: multihulls_at_steamradio.com G'day, Welcome back, Joe. > >Alas, Rob Denney does a disservice to history and truth by calling his > >lopsided catamaran a proa Harry was designed around some very specific parameters. What type of boat this lead to was never a concern. Pacific proa is the nearest terminology in current use, hence I (and every other proa interested person I have spoken to) call it a Pacific proa. If you can come up with something better, feel free, but it is hard enough explaining how a proa is better than a cat or tri, without getting tangled up in new names. Please do not be naive enough to suggest some ancient Polynesian name. Harry is far more a Pacific (European title) proa (adapted European term) than it is a traditional Pacific Island craft. > >He has missed many key features of the > >Pacific proa, most important of which is that the main hull to leeward > >carries the load, not the windward hull. This is fundamental to > >everything else including reduced mass of connecting structure, reduced > >mass and volume of weather hull and extra speed possible by lifting the > >weather hull free of the water. Indeed, it is crazy to claim Pacific > >proa advantages for his ugly and dysfunctional catamaran. Don't forget the "fundamentals" of many crew running back and forth to keep the traditional boat upright, regular dunkings or slow sailing when they don't, the clumsy, inefficient steering oar, the need to move the rig from end to end each time you shunt, the rudimentary accommodation, lack of upwind ability and the dearth of choice in building materials. The traditional proa was ideal for warm water, reaching back and forth across the trade winds in an area with limited boat building resources and incredible sailors. It is not ideal for the conditions and people building and sailing today. As for ugly and dysfunctional: Ugly? your opinion, you're welcome to it. Dysfunctional? not at all. Harry function is to provide comfortable, fast, easy, low cost weekend cruising for my wife and I. It does this better than any other boat either of us have sailed in, read about or heard of. Please let the list know what functions you are referring to when you use the term dysfunctional, or else retract it. The reduced connecting structure required on a traditional proa is nonsense. Whether the righting moment comes from accommodation to windward (Harry), people to windward (traditional) or water ballast to windward (Russ' boats), the load on the connecting structure, for a given weight a given distance to windward is the same. No weight or distance, no righting moment. Indeed, on Russ' boats, with the daggerboard in the windward hull (something never used by the traditionalists), the loads are far higher. I would also point out that traditional Pacific proas do not have buoyant sealed glass/epoxy/plywood pods or their equivalent to leeward to prevent the capsize which is inevitable on a boat with insufficient righting moment. The anticapsize pod was an add on invention of Dick Newicks to stop Cheers capsizing. Russ copied it. Perhaps you should come up with a new name for this category of boat as well. > >Utter nonsense! Mr. Denney is clueless about the physics. The "tipping > >moment" caused by the center of effort of the sail is not affected by > >moving the mast to leeward (or to weather). If you take a catamaran and > >move it's mast to either hull, the righting moment remains the same. It > >may not be intuitively obvious but I assure you that a naval architect > >will confirm this fact. Of course, but read it again, please. I was referring to the load which depresses the leeward bow, as per Greg's question. The athwartships location of the rig has an input into whether the lee hull bow buries or not, I think. See my reply to Tom Speer's post. > > > >Debate has been pointless so I'll conclude simply by saying this: Take a > >look at the cover of Cruising World, March 2001. If that photo of Russ > >Brown's JZERRO gently flying a hull near Bora-Bora doesn't convince you > >which is the correct and true form of a Pacific proa, then just stick > >with a conventional catamaran! Debate is good, it is the vitriol and name calling which is pointless. Russ and his boats are great and they have done a lot of ocean miles. Harry hasn't. However, there is nowhere dry above decks on Jzerro in a breeze, ballast needs to be pumped frequently, shunting is complicated, the boat is generally cruised underpowered and cruising downwind the main has to be removed to stop the mast falling down in an accidental gybe. Understandably, Russ thinks the type is unsuitable for most sailors. The picture of Jzerro probably is gorgeous. And for those with Russ' skill and experience and who sail in trade wind conditions, in daylight, then this variation of the traditional proa may well fit the bill. However, for those who don't, a Harry type Pacific proa (or whatever you want to call it) is a better bet. > >Dick Newick (not Joseph Norwood nor Rob Denney) developed the alternate proa > >form (ama to leeward and all weight to weather), to near perfection in > >1968 with the graceful and effective "Cheers": You have got to be kidding! Dick Newick is a great designer. Cheers was/is a breakthrough boat. It got me started on proas. But, Cheers was a horror to shunt, did not go to windward, had no room inside, was underpowered, lacked fore and aft stability and could only be sailed successfully by one of the best sailors of our time. If this is your idea of "near perfection", it is no wonder that you think traditional Pac proas cannot be improved upon. Believe it or not, all development did not stop in '68. Cheers is _an_ alternate proa form, not _the_ alternate. Jzerro and Harry are others. All three are pretty good at what they do, compared to conventional cats, tris and traditional proas. > >It's not the variation or experiment I object to, it's the dubious > >claims and misrepresentations I keep hearing, along with persistent, > >self-serving and at times belligerent attempts to redefine what a > >Pacific proa is all about. Enough is enough. Put up or shut up (again). Specify which claims, misrepresentations and redefinitions you don't understand and I will explain them (again). Also tell us why and how you (who as far as I know, have never built a decent sized proa, and whose total experience of the type is as a passenger on a day sail on SF bay plus some pretty pictures and numbers on your web site) get the arrogance to defend or define the term "Pacific" proa? Not that I really care. Far better to be sailing a Pacific proa, than sitting at home worrying about the accuracy of the name of a boat 8,000 miles away. regards, Rob PS For those who are surprised by Joe's and my intemperate tone, some history. We had a discussion on the proa list a while ago, in which Joe increasingly desperately tried to prove that a Jzerro type proa (which he has been unsuccessfully trying to sell, but hasn't the ???? to build for himself) was superior to a Harry type. Thrilling stuff! As you can imagine from his penchant for personal abuse (and mine for stirring him up), it became heated. He eventually left the list with his knickers in a twist and has not returned. Joe was more than happy to feature harry on his web page as a Pacific proa, until he decided that I (not Harry) was belligerent, at which time he removed it. His despair at my "misuse" of the name has only sprung up since harry has been proven to do exactly what it was designed to do and I have successfully started selling plans. My apologies to anyone offended (or more likely, bored) by our ongoing disagreement. Feel free to hit delete. _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] advantages and optimum uses for proas? Tom From: Rob Denney <carbondesign_at_one.net.au> Date: Thu, 31 May 2001 10:57:50 +0800 To: multihulls_at_steamradio.com G'day, Of course. I was not knocking Cherokee. I meant flying the main hull, something I suspect you rarely, if ever, do. Seems I was wrong about the lateral position of the mast depressing proa bows less than trimaran bows. Sorry to have misled you, although I stand by my other comments and maintain that for a given performance/accommodation, a Pacific proa will be less likely to pitch pole than a cat or tri. Actually, there is some fascinating number crunching and theorizing happening on the proa list on this subject at the moment. A bit arcane for many of us, but I am sure the likes of Tom and Stu would find it interesting. As for the personal insults, I attribute them to jealousy and ignorance, and ignore them. Insulting my boat is a different matter, particularly from someone who has never seen it or sailed it. These insults I defend with all the vigour I can muster. regards, Rob > > > >Not to detract from the main topic of this interesting (and apparently > >contentious) thread, but Cherokee's amas draw only a couple of inches at > >neutral and easily fly the windward ama under sail. > > > >Its sad to see my original question degrade to insults in some cases, but I > >appreciate the thoughtful reponses and did get my original question answered. > > > >Greg Barker > >San Luis Obispo, CA, USA > >Cross 42 Cherokee > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] HEY, JOE! From: Rob Denney <carbondesign_at_one.net.au> Date: Sat, 2 Jun 2001 18:00:41 +0800 To: multihulls_at_steamradio.com G'day, This post is for those dozen or so people who have expressed a (bloodthirsty, most of them) interest in the silly argument between Joe and me. It will be my last post to him unless he criticises my boat. As Joe has not seen fit to justify his baseless attack on Harry's functionality, I assume he agrees that it fulfills it's design functions, and I thank him for this back handed endorsement. He is welcome to his fanatical views on what constitutes a Pacific proa, and to indulge himself calling me names, although I think a cup of tea and a lie down would probably serve to better allay his frustration at not being the world expert on modern pacific proas he once hoped he was going to be. > >I typically skip posts from Rob Denney so didn't see this one (Wed, 30 May > >2001 > >10:35:12 +0800) until scrolling thru the messages on the proa list... Pity you didn't "typically skip" my original post and save yourself a lot of anguish, and the list a load of rubbish. To make sure you get this one, I have changed the subject. Hope it helps. In case you missed them as well, there is also an apology for his lousy typing and an outstanding question for you from Rick Anderson, and a description of his ideal proa (quite similar to harry) from Tom Speer. > > > >First, I created some confusion myself when I said: > > >> >> Alas, Rob Denney does a disservice to history and truth by calling his >> >> lopsided catamaran a proa > > > >I meant to say "Pacific proa". For anyone who really cares about proa issues, > >the distinction between heavy hull to weather vs. heavy hull to leeward is not > >merely semantic quibbling, it is night and day, apples and oranges. The > >differences are so drastic that it is ludicrous to be making the same > >claims for > >the "Atlantic" vs. "Pacific" proa style. The sum total of people who "really care" about whether Harry is a Pacific proa or not numbers one. You. And I still maintain that this is more to do with your obvious dislike for me than it is to do with which side of my boat I eat and sleep. I note from your web site that Ted Warren's boat, Tiny Dancer is called a Pacific proa. This boat also has more than your magical 25% of weight in the weather hull, yet I don't hear you abusing Ted. Good to see that you are back following the proa list, even if you are too arrogant (or scared?) to contribute to it. > > > >Mr. Denney continues to muddy the water by referring to Harry as a Pacific > >proa > >and making claims that really only apply when you have a small hull to > >weather, > >not a heavy one. All the claims I have made about Harry are based on either it's performance, or that of the 2 prototypes I built and sailed. Until you have similar actual experience of a harry type of Pacific proa, I would suggest you keep your opinions on them to yourself. You could also, of course, specify some of these claims and restart this thread, perhaps without the name calling. > > > >Rob Denney wrote: >> >> >> >> Don't forget the "fundamentals" of many crew running back and forth to keep >> >> the traditional boat upright, regular dunkings or slow sailing when they >> >> don't, the clumsy, inefficient steering oar, the need to move the rig from >> >> end to end each time you shunt, the rudimentary accommodation, lack of >> >> upwind ability and the dearth of choice in building materials. > > > >That has nothing at all to do with a modern Pacific proa. Any more than has the percentage of overall weight in the weather hull! You still haven't told us how you came to be the arbitrator of all things to do with modern pacific proas. Honestly, Joe, no one who is actually building and sailing the boats gives a stuff about the semantics. > > >> >> The reduced connecting structure required on a traditional proa is >> >> nonsense. Whether the righting moment comes from accommodation to windward >> >> (Harry), people to windward (traditional) or water ballast to windward >> >> (Russ' boats), the load on the connecting structure, for a given weight a >> >> given distance to windward is the same. > > > >Sorry, not so at all. But math doesn't seem to be your strong suit. Which part of the maths in "...the load on the connecting structure, for a given weight a given distance to windward is the same" are you struggling with? > >Says to me the same thing it did the first time, that you believed moving the > >rig to leeward would reduce your heeling load. You were wrong. Whatever. You are the only person having trouble seeing what I was referring to. I proved it made no difference on W, which I designed and built back in the days when you were still trying to be a proa salesman. > > >> >> there is nowhere dry above decks on Jzerro in a >> >> breeze, ballast needs to be pumped frequently, shunting is complicated, the >> >> boat is generally cruised underpowered and cruising downwind the main has >> >> to be removed to stop the mast falling down in an accidental gybe. > > > >Again, utter nonsense. You have no idea what you are talking about. Maybe, maybe not, but these aren't my words, sucker. They are direct quotes from Steve Callahan's article on sailing Jzerro to Polynesia. The one you (correctly) pointed to as a description of what a Pacific proa is really about. A description which, stripped of all the flowery language and lovely photos, sounded like an uncomfortable, slow journey in a wet boat. > >As to Cheers, what made it so perfect in my mind is that the hulls had > >completely separate purposes. Like a trimaran, that leeward hull was designed > >to immerse without any obstructions. Once you start moving the rig over > >there, > >you need something to keep it up out of the water and hopefully some deck > >space > >to walk on while handling the sails. Weight gets shifted to leeward and the > >fully immersible leeward hull is lost. Load of bollocks! Cheers' lee hull was not designed to immerse. The fact that it did when pushed hard was one of the shortcomings described by Tom Follett. The two beams sticking up out of the hull is scarcely more resistance than the 2 (smaller) beams on Harry plus the 120mm (5") diameter mast, none of which are ever immersed. Fully immersable lee hulls have been passe in multihull design for some years now, except for the Gougeons rather splendid tris. A well set up ballestron rig (which Harry's isn't yet, but one day will be) does not need deck space on the lee hull to handle the sails. It is all done from the walkway between the hulls, and occasionally, the trampoline. To attribute "perfection" to Cheers based on seperate hull purposes, but not to see the advantages of Harry, which has even more definite (and more successful) seperation of hull purpose shows you to be somewhat near sighted,if not totally blind. > > >> >> Also tell us why and how you (who as far as I know, >> >> have never built a decent sized proa, and whose total experience of the >> >> type is as a passenger on a day sail on SF bay plus some pretty pictures >> >> and numbers on your web site) get the arrogance to defend or define the >> >> term "Pacific" proa? > > > >As before, once again you insult my sailing credentials with no knowledge > >whatsoever about me... You are a total idiot Mr. Denney, resorting again to > >fabrications and baseless insults. As before, once again you refuse to spell out what your credentials are. For the record, I understand that in terms of name dropping famous people on whose boats you have sailed, they are quite impressive. In terms of Pacific proa building and sailing, I think they are as I described them. If not, please elaborate. If your credentials are more extensive than mine on Pacific proas, with or without the weight to windward, I will accord your views more respect. Calling someone you have never met a total idiot in the same sentence as railing against baseless insults is inane. > > >> >> PS For those who are surprised by Joe's and my intemperate tone, some >> >> history. We had a discussion on the proa list a while ago, in which Joe >> >> increasingly desperately tried to prove that a Jzerro type proa (which he >> >> has been unsuccessfully trying to sell, but hasn't the ???? to build for >> >> himself) was superior to a Harry type. > > > >I am not selling anything. Whatever business plans I had in mind five > >years ago > >when I put those pages up have "changed"... I don't even answer proa inquires > >anymore, I have never tried to take money from anyone. My personal dream boat > >will cost about the same as a modern 42' catamaran and until I have the money, > >I'll continue to refine my own plans and share my knowledge freely. In that case I suggest you stop misinforming visitors to your web page, which has not changed in any relevant way since then. I'd further suggest that if you "refine your plans" away from the boat on your web page, and towards a Harry type, you a) will not be wasting your money in the unlikely event that you do build it and b) will spend a hell of a lot less of it. > > >> >> Joe was more than happy to feature harry on his web page as a Pacific >> >> proa, until he decided that I (not Harry) was belligerent, at which time he >> >> removed it. > > > >Your mis-statements are so boring. I created and hosted pages of Harry in the > >spirit of proa fellowship but pointed out immediately in my first > >correspondence > >to you that it was really an "Atlantic" proa, not a "Pacific" proa. I'll look > >it up if I must but please, the difference has been obvious to me all along. Good for you. Unfortunately, neither I nor the rest of the list give a toss one way or the other. Try the proa list, you may get some support from someone there. It certainly was not an issue until after I had comprehensively shown (on the proa list) that a Harry type proa fulfilled it's designated functions better than any other type of boat, particularly the type you were pushing at the time, which has serious shortcomings, as described by Steve Callahan. So, that's it folks. What was shaping up as an epic battle about the pros and cons of weight to windward pacific proas has ended with scarcely a relevant comment being made. The worst the genre's loudest, least informed critic can come up with is that he thinks one example of them is ugly and that they are misappropriating an artificial description owned and controlled by Mr Pacific proa, Joe (facts un considered, keep up pretentiousness) Oster. I'm out of this discussion unless he knocks my boat. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] answers to proa comments From: Rob Denney <carbondesign_at_one.net.au> Date: Mon, 4 Jun 2001 13:38:00 +0800 To: multihulls_at_steamradio.com G'day, Tom, your analysis looks interesting. Do you mind if I post it on the proa list? There are some number crunchers there who consider the multihull list to be a little boring (not this week!) so don't subscribe. Alternatively, perhaps you could join the proa list. Your analytical skills would be much appreciated. Ted, Thanks for the compliments about the difficulty of designing a working proa. Impressive numbers for TD. What is the hull laminate and who built it? Where is it now? Of all the current Pacific proas, this one has the best chance of proving the type in a race. Have you raced TD? How did it compare? Guy, Very droll analysis of pacific proa types, and one which the builders/sailors, if not the cyber types, agree with. However, they ain't mythical. I raced my first prototype (5m plywood Pacific proa) and did pretty well against Lasers and slow beach cats. My second prototype (all carbon/foam/balls to the wall 7m) regularly beat Hobie 20' with spinnaker, before I broke it) I have raced Harry (12m Pacfific proa) a couple of times in mixed fleets. Held onto a hot, stripped out F31 reaching and running, got beaten upwind. Mainly due (I think) to an excessively bendy mast making sail trim difficult. I appreciate that this is no excuse, and that what I should have done was thrown away the mast and sails and bought new ones from Sweden. However,as the total cost of Harry was three quarters the cost of the F31's (recently broken and replaced) alloy mast and wires, this was not an option. I converted the mast into a wing mast by adding plywood sides to the original tube, making it a fair bit stiffer, and heavier. I then shifted across the country so missed most of last summer after chopping Harry in 3 to get it into a container then rebuilding it. Harry will be racing this summer, in Perth, the 3rd windiest city in the world. The bullshit will stop! Main competition is Rapid Ride, a Grainger 30' Firebird type cat whose mast also cost more than harry did. They should thrash me. If they don't, or even if they only beat me by a leg or two, you will be hearing all about it. To be competitive, I need to spend some money. No problem with this, but until I know that it will be well spent, I am wary of doing so. Hence the slow and cautious build up. This is not helped by a host of new ideas I want to try, all of which take time, most of which aren't speed related, and the fact that harry's hulls are rough and heavy, as befits a cruising prototype. I really should replace them before spending money on the rig to optimise performance. W may also be racing this year. Plan is to go over in August and do a qualifying voyage for the Coastal Classic in October. The mythical speed you refer to is theoretical based on it not being possible to get a lighter boat for a given length. All of the handling problems associated with Pacific proas have now been solved on Harry. The next step is convincing someone with enough money and the right attitude to racing to approach the type in the same way as they approach racing conventional boats. The performance rewards from racing the first of a new type will be far higher than spending thousands trying to improve existing very competitive boats by small parts of a per cent. Ugly. Harry was designed to specific criteria. Looks was not one of them. I found it hard enough to fit two permanent double berths, galley and full headroom into a small boat without worrying about looks as well. Later models have improved somewhat, but true beauty will come from one of two paths. First, someone with an eye for the subject will design one, which will certainly be heavier. Second, someone will spend $Aus60,000 ($US30k, 20K quid) building a racing Harry, weighing about half as much (300 kgs (660 lbs)) and beat boats costing 5 times as much. Shortly afterwards, perceptions will change, as they always do, and fast and ugly will be percieved as not so ugly after all. Meanwhile, have a look at Russ Brown's proa, Jzerro. Out there, doing it and definitely good looking in the currently accepted use of the term. Chris, Peter, Brian and any others in the anti proa fanatic brigade. Give me a break. Let me know how you would have responded to totally unsupported criticism of yourselves and your boats based entirely on a personal dislike for you? I think you would defend, in the same tone as the attack. Regardless, if you don't like it, hit delete. Kevin, and anyone else who wants to visit Perth and sail on harry: Let me know the flight arrival time, I'll clean the sails and stuff out of the spare room and pick you up at the airport. Rick: Keep pushing, but I have been trying to get this information for some years. Seems to prove that his experience level is as I stated it. Maybe some of Joe's "friends on the list" could fill in the details? Dave Culp: Never say die, eh! Or is it "fling enough mud and maybe some will stick"? What are you talking about with unseamanlike? After our "long and boring discussions on the types", this is the first time you or anyone else (even Joe) have mentioned this. Please don't do a Joe and either ignore this or rant on about it being so, because you say it is. Be specific, with examples, numbers, facts. Also explain how it is different from the windward hull of a non bridgedeck cat, in terms of seaworthiness. If there is something I have overlooked and which hasn't shown up so far, I want to fix it. As a "friend of Joe's" maybe you can fill in some of the details for Rick? It is unfair for you to blame Greg for the nastiness on this thread. His question and my answer were both legitimate and polite. Joe's reply to me was personal,flawed, unsubstantiated and nasty. For those curious about weight in the windward hull of a proa, there is no magic, nor do you get something for nothing. Low weight in the windward hull will result in: Less beam stress, though not much less as Pacific proa rigs are stayed to windward, thus supporting the beam and the weight of the weather hull Less drag, though not much less, as the lee hull can be much smaller if everything is in the weather hull. Almost the difference in weight size and drag between the main hull of a tri vs one of the outriggers Claimed smoother motion through the water. As the only person to have sailed on both types, I did not notice any particular difference. My wife, who has been seasick on every type of boat available, has yet to throw up on Harry, including beating into 20 knots and wind over tide waves. Less righting moment so frequent sailing on your ear, reefing and sailing underpowered A weight to leeward pacific proa (Oster/Culp) is like sailing a lightweight cat with the crew, the rig, 75% of the windward hull, the outboard, the batteries, the anchors, the spare sails and all movable gear on the lee hull. Up to 5 knots or so of breeze, it may be faster. Over that, you want to start moving things to windward. In a pacific proa, this can be in the form of: Crew running back and forth along the beam, carrying gear, Pumping water into the weather hull. Combined with a low drag version of the Harry option, this makes huge sense on a racing proa, none at all on a cruising one, Having everything except the rig permanently to windward,(the Harry option). Another way of looking at it is the difference between sailing a tri with the leeward hull removed compared to sailing with the windward hull removed. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] answers to proa comments From: Rob Denney <carbondesign_at_one.net.au> Date: Tue, 5 Jun 2001 12:11:23 +0800 To: multihulls_at_steamradio.com G'day, Thanks, I'll post it today. Any relevant feedback, I will let you know. Not sure I understand your point about the 60's and The Race cats. Surely it is not a question of how far forward the centre of buoyancy is, but of how much buoyancy there is. A tri/cat/proa float with a bluff bow tapering to a pointed stern will have the cob about 1/3 rd aft. The same hull with a bluff bow at each end will have the cob in the middle, but will have more diagonal stability. To increase it further make the double ender twice as big. cob will still be in the middle, diagonal stability will be enhanced. With sideways stability, the size of the lee hull does not matter, as long as it exceeds 100% (in theory. More once waves etc are allowed for). Diagonal stability can be enhanced by higher, wider lee hull bows, which are not allowed for in any calculations which only deal with loa, boa, weight and sail area, as you pointed out. I think the reasons the 60's are so fast is that they are incredibly well developed, and that in the unlikely event the maxi cats reach the same level of development they will be far faster. The current crop of Race boats are at about the same level of development as say, Apricot and Paragon. Both 60' rocket ships, cleaning up the 80 footers of their time, but underpowered dogs compared to what's winning today. There is also the difference that the Race boats had to survive the Southern Ocean and carry crew/food/etc for 60 days, the 60s "only" the North Atlantic for a fortnight. Regards, Rob > >No objections - go ahead. Actually, it applies to any multihull, not just > >proas. One conclusion I reached from it is that the Open 60 tris are so > >fast for their size - almost as fast as the big cats in The Race - because > >of the diagonal stability afforded by the ama's forward center of buoyancy. > > _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Tiny Dancer From: Rob Denney <carbondesign_at_one.net.au> Date: Tue, 5 Jun 2001 12:14:08 +0800 To: multihulls_at_steamradio.com > >As I understand it Proas were banned from most of the 'classic' races such > >as the OSTAR after a series of capsizes. From memory I think these were Rory > >Nugent on Godiva Chocolatier and Jean-Marie Vidal's Eterna Royal Quartz in > >the Twostar. This killed their development as ocean racers. > > > >Alan > > G'day, They were and it did. However, these were Atlantic proas, rig and accommodation on the windward hull, both hulls the same length, all variations on Cheers. The (large) ones we are building and discussing now are Pacific proas, different length hulls, rig to leeward, and either accommodation in the shorter windward hull, or some form of truncated trimaran float to leeward to stop capsize. The only Pacific proa to enter a major race (Rhoute de Rhum) had the accommodation in the lee hull, water ballast in the weather hull and was launched the day of the race. It also had a cantable beam allowing the weather hull to be raked aft. Forecast was gales on the nose. The skipper (wisely in my opinion) accidentally released the rope holding the beam, it folded back against the lee hull and the boat capsized just before the start. regards, Rob > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] answers to proa comments From: Rob Denney <carbondesign_at_one.net.au> Date: Tue, 5 Jun 2001 12:28:40 +0800 To: multihulls_at_steamradio.com G'day, When you jerk my chain, please tell me off post so i don't make a dick of myself. Under normal circumstances, I might have clicked, but i am a tad sensitive after Joe's efforts. You are right, of course. Harry. as built, is not seaworthy enough to go out of sight of land (some would say out of swimming distance). This is not entirely a function of the cost, more of the experimental way it has been put together. Harry type proas most certainly are capable of extended voyages offshore. Regards, Rob > >Rob Denney: >> >>Never say die, eh! Or is it "fling enough mud and maybe some will stick"? >> >>What are you talking about with unseamanlike? After our "long and boring >> >>discussions on the types", this is the first time you or anyone else (even >> >>Joe) have mentioned this. > > > >Well, it seems I've used the wrong word. According to the best > >dictionaries I find, the term "unseamanlike" is best described as > >"(not) having or showing the skill of a practical seaman" (Mirriam > >Webster) or "lubberly, landlubberly -- (inexperienced in seamanship; > >'of all landlubbers the most lubberly')" (Wordnet). In other words, > >"unseamanlike" relates to people and their actions, not boats. Sorry, > >I didn't mean it in that way at all. A better choice might have been > >"unseaworthy," defined as "(In)capable of putting to sea and (un)able > >to meet sea conditions." (United States Merchant Marine Glossary of > >Maritime Terms and Definitions), which better fits the sentiments > >leading to my statement. Oh, and I'm pulling yer chain, mate. Better > >you than Joseph, he goes ballistic sooner. > > >> >>Please don't do a Joe and either ignore this or >> >>rant on about it being so, because you say it is. Be specific, with >> >>examples, numbers, facts. > > > >OK, let's take a vote: Audience, if you were told a bloke had built a > >40' multihull for $5000 in materials and a couple hundred hours > >labor, weighing 1200 lbs, wet, and "able" to sleep 4 at sea, would > >*you* characterize the boat, sight unseen, as a) seaworthy, or b) > >unseaworthy? I'll stand by reader input, and will happily retract my > >views, as and if sufficient others disagree. (also see above, > >regarding chains and ballistics) > > >> >>Also explain how it is different from the >> >>windward hull of a non bridgedeck cat, in terms of seaworthiness. If there >> >>is something I have overlooked and which hasn't shown up so far, I want to >> >>fix it. As a "friend of Joe's" maybe you can fill in some of the details >> >>for Rick? > > > >No, I won't get into all of this again, Rob. I gave the references > >yesterday, and I believe nearly all was said clearly, last month. > >Anybody interested has only to follow the links. > > > >OK, if you've read this far, dear Audience, I'm going to shoot myself > >in the foot: > > > >Rob Denney is an accomplished and intelligent yacht designer and boat > >builder, perfectly capable of doing all he claims. Harry is an > >admittedly *very* extreme concept boat, remarkably well thought out > >and executed, and in fact, can do all Rob claims it can (well--most; > >I've never sailed the boat). That I do not personally like the design > >speaks to my prejudices, not to his nor to the boat's abilities. My > >weirdness just runs in a different direction than Rob's. > > > >Dave Culp > > > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Real sailing? (was joe's credentials) From: Rob Denney <carbondesign_at_one.net.au> Date: Wed, 6 Jun 2001 16:14:00 +0800 To: multihulls_at_steamradio.com Mr Fish asks: "But is sailing on a proa, really sailing?" Well, no, at least not compared with what you are probably used to. Real sailing is often referred to as standing in a cold shower tearing up $100 bills. On Harry type proas it is more sitting in the sun and sailing past other sailors as they get wet and tear up their money. Harry has one lightly loaded sheet to control both sails. That's right. Hoist the sails at the beginning of the day, and barring large changes in wind strength, the only control required is a single, lightly loaded sheet (slls). No winding on winches, no mainsheet tracks whizzing back and forth, no highly loaded sheets and no flapping sails or ropes waiting to knock someone out. Not only very low initial and maintenance cost, but very low effort as well. Harry has 2 hulls. The leeward one (long, narrow and low) has the rig and rudders (no centreboard or keel), the windward one has the sheltered cockpit, the steering position and the accommodation. Hence it's nickname of the 'chardonnay hull'. My wife and her friends sit there sipping while I sail the boat, close enough to them to join the festivities if I wish. Tacking/gybing/shunting require no input from the passengers, no changing sides, no flogging sails and no pulling on ropes. It doesn't require a heck of a lot of effort from the sailors either. Release the slls, unclamp one tiller extension, clamp the other and pull in 3m (10') of slls. All done sitting down. Takes me about 8 seconds, singlehanded. As importantly, it is all done under perfect control. No possibility of getting in irons, or having the sheets catch on the mast, or someone's fingers in a track or winch. If you want to stop for a chat during a shunt, you can. The boat sits waiting for you. There is no foredeck work. When you want to change or reef the headsail, you release the slls and the rig swings round so the jib is pointing upwind. All jib handling is done from the comfort and safety of the walkway in the middle of the trampoline. No need to clamber up to the bow, no sails falling in the water, no flogging sheets and no risk of the crew falling overboard. The motion of Harry is probably unusual for you as well. It heels less than a trimaran, and upwind, both the long leeward hull, and the short windward hull meet the waves at the same time. This make for a very easy, dry passage upwind. So no, harry-type proa sailing is not real sailing as you probably know it. It is cheaper, far less effort and faster. Possibly more boring, if you get your excitement from hard work and avoiding potential injury. If you have any more questions, please ask them. For example, you might ask, "Is building a fast boat with 2 double berths and full head room for $Aus20,000 ($US10,000) worth of materials _really_ boat building?" PS With regard to your kite boat comments: Dave will fill you in on kites' enormous potential, but meanwhile, I am launching my 5m (16') kite powered catamaran this weekend. Weighs 30 kgs (66 lbs), built of 1/4" ply, cost $Aus120, plus $Aus700 for the kite, could be capable of 20+ knots. Sort of a kite board for those who, like me, are too fat or old to kite sail standing up. I will let you know how it goes, as you are obviously a technology buff. Regards rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Proas in pieces/ultralight proas From: Rob Denney <carbondesign_at_one.net.au> Date: Wed, 6 Jun 2001 16:26:25 +0800 To: multihulls_at_steamradio.com > >Much as I have been trying to avoid this proa discussion, I have heard > >that a certain proa was beached in pieces on Cheltenham beach near Auckland, > >New Zealand, after Wracking itself to bits after trying to watch the > >Auckland to Noumea yacht race a couple of weeks ago, on a very windy day. > > Maybe conventional, multi-beam structures that resist wracking are > >sensible and seaman like... Tim, You disappoint me. I thought you would at least have phoned Gray before going public with such cheap (and wrong) shots. My understanding of what happened is much less dramatic. During a bear away in strong wind conditions one of the 10mm Vectran lines which keeps the hulls pointing in the same direction broke at a "temporary" knot, which should have been spliced many months ago. The hulls yawed and came together. The cabin hull got under the boom and lifted it and the mast out of the boat (not sure how) breaking the mast hold down line, and causing some damage around the top mast bearing. Neither the mast, boom, hulls or beam were structurally damaged. There is nothing to stop the W hulls wracking (they are free to pitch independantly), therefore it cannot "wrack itself to pieces". W was towed ashore and left on the beach. Gray and his crew put it on it's trailer (try that with the components of any other 40 footer!) and took it to the workshop for repair, and some alterations which have been on the drawing board for a while. Should be back in the water next month. W is probably the most radical boat built anywhere in the world in the last 10 years. (Any boats with better qualifications, please let me know, preferably on a different thread.) W has been sailed regularly since it was launched, in breezes up to 35 knots. Breakages have been minimal, and like this one, easily repaired. If Tim's comments are typical of what he would have bought to the proa discussion, it is a good thing he "managed to avoid it". For what it's worth, W is a bimaran, not a proa. Yes, I know this is a totally new word, but then W is a totally new type of boat, according to both the trade mark and patents offices. Joe wrote > >A single 240 lb. person would be 20% of Harry's claimed weight, two such > >people >would be 40%! That ratio is light years away from the 50' Moxie, > >for example, >at 10,500 lbs. where five such people would be only 10% of > >her displacement, or >the 76' Double Bullet II at 15,000 lbs. where 1000 > >lbs. of crew is less than 7% >of her displacement. Not only are the Harry weights light years away from Moxie and DB2, but so is the concept, the cost, the accommodation, the ease of sailing and their designed purpose. While we are all glad that you have sailed on these marvellous machines and are finally sharing your knowledge of them, they are hardly a valid or relevant comparison. It is not necessary to have an expensive, heavy boat, with huge, costly, highly loaded rig and lots of expensive gear to be be a successful fast, low cost weekend cruiser for 2 people, one of whom is chronically seasick and refuses to pull ropes. The trick is to keep the loads as low and localised as possible, then to put the crew where they can be of most use, especially if it also keeps them dry and close to the ice box and kettle. This is what I have done with the harry type Pacific proa. > >I think the point is very clear in this photo of Harry's predecessor, U: > >http://www.schachtdesign.com/proafile/artwork/gallery/U.jpg Wondered how long it would take you to use this photo. U was a Harry prototype in many ways. It was designed primarily to go fast, which it did, and sort out rig and steering solutions, which it also did. It was also designed 'on the limits' as befits a fast boat. In it's lightest format it weighed considerably less than Cogito, the very expensive C class cat of the same length. Consequently things broke. The beam breaking was an interesting situation. We flew a hull, maybe 3m (10') in the air, and accidentally dumped the single lightly loaded sheet, removing all power and heeling force. The flat bottomed hull came down with a bang, rapidly followed by two others as the beams broke. Analysis showed that one of the beams had been inserted the wrong way round, so that the tapered laminate was at the wrong end. Hence the points of breakage being in 2 different places. Probably would have broken anyway, as I had never allowed for slamming loads from a flat bottomed weather hull as it originally had a round bottom hull. I think there is also an article on U and the reasoning behind it's development (and the name) on the schactdesign site. I did the engineering on both U and harry, and tend to err on the light side of safe on my personal boats. Consequently, I am not surprised when things break, using it as a prime diagnostic tool. I would obviously never do this for boats on which others sail. All my boat plans for others to build are fully engineered by one of two very competent engineers. The fact that U's beams, (along with a few fittings on it, it's predecessor and harry) have broken, proves absolutely nothing about whether proas should be built lightly or heavily. All it proves is that in my efforts to push the limits, I occasionally exceed them. At least I do it on my own boats, with my own money, and am not afraid to publish the results when it goes wrong.. > >As to the issue of 1200 lb. boats (40 feet long!?) safely crossing oceans, > >I >doubt it. As you doubt everything to do with me. Be interesting to hear the basis for such a sweeping condemnation. And why you consider weight to be such an important driver of what is safe. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Proas and developments From: Rob Denney <carbondesign_at_one.net.au> Date: Thu, 7 Jun 2001 22:52:21 +0800 To: multihulls_at_steamradio.com G'day, > > But did I read right: > >During a bear away in strong wind conditions one of the 10mm Vectran lines > >which keeps the hulls pointing in the same direction broke at a "temporary" > >knot, which should have been spliced many months ago. The hulls yawed and > >came together. > > > > There are 10 mm vectran lines holding the hulls in line???? The failure > >of one line can cause such damage? Why not? The individual yawing forces on the hulls are quite low as long as they point in the same direction. 10 mm Vectran has a breaking load in excess of 3 tonnes, many times higher than the total weight of the boat. It was probably reduced by more than half by the knot, and the load increased for the angle it was working at (that is, it was not directly between the bows), but still more than enough, I think. I need to know a bit more about the circumstances, but at the moment would replace it with an identical line, albeit spliced. There are lines on conventionalnon bridgedeck multis which would cause far greater damage if they broke. The dolphin striker and the seagull striker being the obvious ones. From what I understand, there was not a lot needed to be done to straighten the boat up and motor home. The CG arrived and were chosen as the easiest option. FWIW, the boat was motoring at 6 knots a few months ago, after some adjustments to the vectran had been made. It had not been tied off, and the bows came together, stopping the boat in less than a boat length. No damage was done. This is a vessel that is expecting to be > >given a Cat 3 safety certificate to race up the rugged, exposed, Northland > >coast at night? Obtaining a safety certificate for a radical boat is always a problem. Take it from someone who knows! Hence the need to do a proving voyage or three before we apply. I think you exaggerate the Northland coast a little. I believe a windsurfer has competed in the race, as well as an 18' skiff. When I was a boy, i cruised it in a 22' keel boat, as do many others. I think there was even some nutter who sailed up and down it in his 16' racing cat in order to enhance his design credentials? (grin) > > This is a boat that has been underdevelopment for some years now, and we > >are yet to see it race. There are many other Multihull yacht races in > >Auckland beside the Coastal Classic. Surely the litmus test of such a > >radical racing yacht is racing amongst similar vessels. Indeed, but W is not a racing yacht and was never designed as such. The spec was for a fast, trailerable, day sailor/occasional overnighter boat for a couple, one of whom does not sail. Kawau for lunch, home for dinner sort of thing. It fulfils these requirements admirably. All the development so far has been towards this end. If the spec had been for a racing boat it would have been far lighter than it's 450 kgs (990 lbs) and carried a much bigger rig. The only reason for doing the CC is because me and a couple of other interested parties want to see how it performs. > > Above all, boats have to be safe. This is the thinking that leads to all boats being the same (including having the same faults), and stifles innovation. The only way to find the limits with new ideas or boats is to push them till something breaks. As long as this is done under controlled conditions, with adequate back up, then the only harm is to the owners/designers/builders pride and wallet. W has been sailed in some pretty hairy conditions (worse than the day the string broke) without dramas. The next step is to get a competent crew, a decent weather forecast and possibly a support boat and see how it performs on a longer trip. Not until this has been done (and any problems remedied) will it be doing the CC. I presume you aren't intertested in crewing? regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Proa Shmoa From: Rob Denney <carbondesign_at_one.net.au> Date: Fri, 8 Jun 2001 18:12:25 +0800 To: multihulls_at_steamradio.com I'm wondering how practical proas > >are for the vast majority of us who are struggling to keep our heads above > >water while trying to maintain whatever boats we can just barely afford. > > >From the perspective of the real world, how many of us would even consider > >using a proa on a sunny weekend cruise? > > > >A.M. Genen My wife and I sunny weekend cruise at every opportunity. Works well. Maintenance on a boat with no winches, tracks or highly loaded sheets, minimal rigging and lowest possible external and internal surface is pretty low. Running costs are very low with a 5 hp outboard on a boat that sails well. If socializing is part of your reason for cruising, there are never any shortage of people rowing or swimming over for a chat, and to ask questions. > >I have, however, been wondering about heavy weather strategies in proas. My > >guess is that their tolerance for breaking seas on the beam would be somewhat > >less than a tri of comparable length. For example, I would not want to get > >caught in 11 foot breaking seas on the beam in my Cross 42. I would imagine > >that a proa of similar length would want to make a strategic change well > >before that. Do our resident proa enthusiasts have any experience with this > >type in heavy weather? > >Greg Barker None whatsoever, but I would expect a Harry type Pac proa to lie ahull in moderate bad weather, with the windward hull to windward. Towing a drogue using one of the anchor bridles (one at each end) would work the same way as it does on other multis, as would lying to a parachute. With very low draft (4") of the lee hull, 12" draft on the weather hull, removable rudders and no centreboard, I would expect it to be very difficult to capsize with wind or wave action without sails up. 11' waves breaking n the beam aren't my idea of fun either, but I see no reason why either boat would have trouble. > >Wonder if there is a proa equivalent of the Catalac or Gemini as a > >cruiser for us masses? Not a production boat, rather a proa design in > >the same "station wagon" genre. What would that look like? It would be > >the other end of the design spectrum. > >Marc Interesting question. There is nothing currently around. Proas gain most of their benefits from being light, fast and cheap, as did cats, originally (Wharram, Choy, etc). No reason I can see why they could'nt be heavy and roomy. I expect they would look a bit like a Catalac or a Gemini, except with the rig in one hull, and the hulls double ended. Big decision would be whether to have standing headroom on the bridgedeck, or only in one hull, or in both hulls. Hulls would be a little longer, wider or deeper to regain the payload lost from the fat stern, except both these cats are more or less double ended, I think? Windward hull could be a little shorter than the leeward one, but not much. More usable space inside (mast and chainplate bulkheads eliminated, at the expense of a mast being mounted midway along the lee hull), but the cockpit would be central (safer, drier, easy to make fully enclosed, and on the same level as the boom). More space outside, with no rigging in the way. Safer, as you could stack all the heavy stuff (fuel, batteries, etc) in the windward hull. Maybe narrower overall as well. Probably use large rudders and no keels, so windward performance would be much better. Downwind would be much easier. No shrouds in the way, and possible to ease the main past 90 degrees. An accidental gybe would be "soft" because of the rig. Shunting with a ballestron rig would be a lot easier and safer in this type of boat than tacking with either a conventional or a ballestron rig, as you would not be trying to force a lot of weight through the eye of the wind. Therefore there is no headsail to back then winch in. This and the maneuverability would be it's biggest pluses. Probably cheaper as there would be lower loads, no forebeam and little or no deck gear, more or less the same advantages as for a conventional boat with a ballestron. Would still need two rudders, but they'd be fore and aft on the same hull as the mast. Make them removable, in cases, for drying out. For boats sailed a lot in shallow water, maybe some secondary very shallow rudder system. It would steer far better than a normal heavy cat, and would only need one engine. Not a bad solution, I think, certainly an interesting challenge. You would get a lot of weird looks, probably even more than I get in harry! This may be it's biggest negative. If you like, let me know (on or off list) what the minimum requirements are for such a boat, and I will sketch one so you can see how it looks. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Proa Shmoa From: Rob Denney <carbondesign_at_one.net.au> Date: Sat, 9 Jun 2001 12:22:49 +0800 To: multihulls_at_steamradio.com G'day, > >While I don't have experience with proas, I would not think that this would > >be a desireable strategy in the eleven foot breaking seas I described. You > >generally want either the stern or bow quarters to lie to the seas. Heaving > >to puts the bow quarter to the seas in most small sailing vessels, and I > >could easily see this working with a proa. However, when things amp up to > >the level indicated above, I would think the suggestion of lying to a storm > >anchor makes more sense. <Greg Barker Agreed, although we lay ahull, beam to the seas, in my Iroquois cat (30' long, 13' wide, weighed maybe 2 tonnes) with the rudders and centreboards up in waves big enough to occasionally break completely over the boat (F8, Bay of Biscay), never had any trouble. Might be a more comfortable ride with a drogue or sea anchor, but conditions would need to be a fair bit worse than this, or other compelling circumstances (lee shore, entering port at night, etc) to justify the effort. Heaving to implies some sail up, the centreboard down and the rudder(s) luffing the boat, with the possibility of getting thrown backwards by a breaking wave. Possible rudder damage, but more worryingly, the boat might end up on a broad reach, just prior to the next big wave. This has always scared me on multis. I much prefer to remove as much drag as possible from the air and the water, and go where the wind and waves take me. This applies to shallow draft, light weight multis. Fixed keel, or heavy ones would need to be treated differently. Same conditions, same place, in an Apache cat (11 tons, 45x20) with fixed keels and rudders, we lay to a sea anchor (storm jib with anchor chain on one corner), for 18 hours, although not very successfully, as the damage took a couple of months to repair. > >Just curious Rob, but how does Harry lie simply ahull with the > >rudders turned at 90 degrees? Still Crazy will sit this way for > >hours, at least in moderate conditions (only stuff we sail in. ;-) > >The boat fairly aggressively reacts to wind shifts, remaining dead > >across the wind. > > > >A proa with dual spade rudders, capable of 360 degrees rotation, can > >set same at 90 degrees to the hull. This way, the boat can make *no* > >way, in any direction. Put the heavier, deeper hull to windward, and > >it seems to me the boat'll lie there through thick and thin. Works > >for me; what do you think? > > > >Dave Culp Dunno, never tried it, but see no reason why it wouldn't be exactly as you say, although the windage from the wing mast may cause it to move about a bit. Could always align this at 90 degrees as well, if zero way was required. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] (MHML) Capsize From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Fri, 6 Jul 2001 16:02:16 +0800 To: multihulls_at_steamradio.com G'day, It is very rare that bad luck causes a capsize. I cannot think of any. It is always human error, inasmuch as there is always something more that they could have done. A crew which sails 2 handed in a boat which requires a full racing crew to safely drop the main in a squall is not unlucky, they are nuts. The fashion for 3 stayed rigs has been foisted on cruisers by the racing fraternity, who want close sheeting angles, huge roaches and rotating rigs on boats which flex too much for a conventional stays and spreader rig (also a flawed solution, but far safer) and which always sail the angles downwind, with large spinnakers that require more muscle than mum and the kids can provide. For any cruiser to have a mainsail which can't be eased out enough to sail dead downwind without constant fear of gybing, and all the consequent wear and tear of the main bending round the swept back shrouds shrouds is ridiculous. As you point out, it is also unsafe, for all boats. Any boat, racing or cruising, which cannot safely run off before the wind in a drama is going to have troubles sooner rather than later. A rig that requires the main to be dropped and the spinnaker hoisted for downwind sailing is also not what most people have in mind when they go cruising. Next time you are spinnaker-only cruising downwind, throw a hat overboard and see how long it takes you to get back to it. Then try it again without the motor. Then try dropping (or socking) the bloody thing in a squall with no mainsail to blanket it. If nothing else, it will certainly put you off falling overboard. These lessons are old news to anyone who has been multi sailing for any length of time. To me, the strange thing is not that they developed, but that owners are so willing to put up with them, and that so many designers keep designing them. The performance gains are not huge, probably less than the benefits of a clean bottom and a serious clean out of the accumulated junk lockers. Yet, presumably because they look like the race boat rigs, every one wants them. regards, Rob >> >>There is a great increase in multihull sailing, newcomers to multihulls, and >> >>an increase of casualty as a result. > > > >Neither of the two recent capsizings seem to be due to inexperience - > >bad luck and pushing too hard, perhaps. > > > >I do wonder if they represent the liability inherent in the > >currently fashionable large main, small jib, no backstay type > >of rig. From recent, though thankfully uninverted, personal > >experience, it seems clear that losing control of the main > >is the major liability. In particular, if you get it pinned > >against the side stay in heavy air you've pretty much lost control > >of the boat. > > > >What I take away from these incidents is that you don't want to > >be flying a full main more than a few degrees off a beam reach unless > >you can be _very_ confident about the conditions. Also seems to > >argue for the spinnaker-only approach to trade wind cruising. > > > >-Scott > >Scott Meyer mailto:Scott.Meyer_at_oracle.com 650 355 0460 (h) > >F41 #17 > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] (MHML) Capsize & backstays From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Tue, 10 Jul 2001 11:50:02 +0800 To: multihulls_at_steamradio.com > >As to some of Rob Denny's comments about this type of rig: > >1. I have always though of falling overboard in the typical > >shorthanded cruising scenario as fatal. It generally is, but it needn't be, with a sensible cruising rig. > >If the crew does notice, that's probably > >time to use the boat knife: leave the spinnaker and motor > >back. Not sure which immutable law of physics it is, but most spinnakers dropped by knife stroke end up either under the boat, then around the prop; or half down with the halyard twisted around the other halyards inside the mast,jamming all of them. Dead crew, stuffed kite, cut sheets and bent prop shafts or dead crew and spinnaker streaming like a flag, unable to do anything tilll it flogs itself to pieces. But at least it had the same rig as the racing guys, and don't forget the resale value.... > >2. I've heard plenty of bad comments about 1500sq foot masthead > >genoas which couldn't be furled, caused uncontrollable jibes, > >etc. Possibly, I'm too sanguine about the whole thing, but > >horsepower is always going to be a two-edged sword. > >Intellectually, the large main (easy to reef, easy to shape, > >dangerous when overpowered downwind) seems like a better > >deal than a large jib (hard to reef, hard to shape, easy to dump > >downwind). The F-boat racers around here (SF Bay) seem to > >like the worst of both worlds: large unreefed main and a screecher. > >I know that there are alternatives (less weight, aero-rig, etc.) > >but: Possibly you are a bit sanguine. But no more so than everybody else sailing on boats with provably (and proven) lethal rigs. Horse power per se need not be a two edged sword. A rig on a short handed cruiser which was designed for a fully crewed racer is not a sword, it is a bloody great gun, with a hair trigger. > > > >3. I'm a boat user, not a boat builder or a boat designer. > >I have to trust other people to do those jobs. Is this the same as saying that you know the rig has dangerous failings, but because it was designed by a "boat designer" you are quite happy to sail with it? Or that, when it capsizes because you couldn't ease the main past the swept back stays, or lower the main on any point of sail broader than a reach, you will be able to sue the designer? Paul Nudd (with whom I have raced many enjoyable miles) Basically agree with all here. I don't see any significant arguements against the type of rig proposed (and used) by Rob Denney for the cruising situation except if you ain't got it it's probably too much trouble to change. Definitely the way to go if you start with a clean sheet of paper, which Rob always does. Come to think of it he usually doesn't, he just gets in and builds it. Why waste time drawing it when with a little (lot) more effort you can build it. Rob I'm not proposing anything specific, just trying to get people to think about their rigs before anyone else gets killed, or any more boats fall over. Maybe even get some discussion happening which is a bit more meaningful than the dubious delights of sunny Queensland. Flogging a dead horse, I suspect. Clean sheet? Look on the backs of some of your old charts. You will see some of my early proa doodlings. What's the score with the latest capsize off Sydney? (as reported by Nusa Dua) Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Escape Hatches From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sun, 15 Jul 2001 14:55:34 +0800 To: multihulls_at_steamradio.com > >Thanks for your reply, but, who, puts fuel and batteries where leaks can get > >into the accommodation right way up or upside down? I suggest that with a > >multi if the boat is not habitable upside down it is called a design fault! > >And if fuel and batteries have any means of venting or leaking to the > >interior then how do they obtain a survey certificate? > >Someone who actually had the experience suggested a hatchet to put a hole in > >the optimum spot was better than a hatch which cannot be placed on the keel. > > G'day, I used to aspire to this theory, but when I had to put it to the test, discovered that it was easy enough to make a hole in 6mm ply, but that to make it big enough to get into entailed a lot of work, and a very jagged hole. We only made the hole to get flares and stuff out of the boat, but I would not recommend a hatchet in rough seas, or if someone was inside relying on it. It is also very easy to drop over the side, as my crew discovered! Later in the same little adventure, the Irish navy attempted to sink the upside down cat as a "hazard to navigation". Three huge stokers approached the boat in an inflatable. One of them swung a dirty great fire axe with all his strength and weight onto the keel which was solid glass, maybe 10mm (3/8") thick. The axe bounced off, almost throwing him overboard backwards. They then spent 30 minutes hacking at the foam sandwich hull (700 gsm 20 ounces glass either side of 15mm foam). They were able to make holes (splits is a better description), but nowhere near big enough to get in to. The next sinking attempt was by almost the entire crew with automatic small arms fire. Finally, as pub shutting time was drawing near, the skipper ordered the antiaircraft gun be used. Took 50 rounds, but it eventually sank. Fortunately, they kept the boozer open till we got there. I would not recommend a hatchet for anything more than a beach cat, and a lightly built one at that. To not have a hatch and upside down accommodation on a multi on an overnight voyage is lunacy. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Sea anchors (was Gemini Across the Atlantic) From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sat, 28 Jul 2001 11:55:08 +0800 To: multihulls_at_steamradio.com > > > >The main difference I can see between a shunting proa and a tacking boat is > >that the proa HAS to go beam to the waves as a matter of course while the > >tacking boat does not. > > > >Cheers, > > > >Tom Speer Correct, and I suppose in theory, this makes a proa more susceptible to capsize in these conditions than a cat, during a tack. However, look at it a little more closely. The shunting boat is under control the whole time, regardless of how much sail it has up. It can also time it's shunt to a period of relative calm a lot easier than a tacking boat. Tacking in a boat with little or no sail up, in big waves/high winds, is almost certain to result in getting in irons. Then you have the boat going backwards, out of control, down large waves while trying to steer it in reverse. Ease your iron grip on the wheel, and you will be lucky not to lose your steering, and your fingers. Of course, the sensible skipper in both cases has his sea anchor out, all his water foils clear of the water, and is down below with his bible and a bottle of scotch! Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Sea anchors (was Gemini Across the Atlantic) From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sat, 28 Jul 2001 12:00:36 +0800 To: multihulls_at_steamradio.com You have just described one of the advantages of a proa, theoretically >> >> anyway. > > > >And there lies the whole proa problem...........theoretically anyway. > > > >Guy G'day, Guy, you seem to have a problem with proas. I would like to know what it is based on. I am currently building a 10.5m trailerable proa based on my successful Harry design. I am sharing shed space with a 15m proa which was successfully sailed, partly singlehanded, from Tasmania to Perth, a distance of 8,000 miles in some pretty rugged conditions. The days of proas being "theoretical" are long past. They are by far the cheapest boat possible for a given length and designed carefully, are extremely easy and safe to sail. They are the closest boat available to Newick's impossible trio of space, speed and low price. While your droll anti proa comments are occasionally amusing, I am curious as to whether they have any basis in fact or are just the results of blind prejudice. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: RE: [MHml] Re: Cat comments From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sun, 5 Aug 2001 22:01:19 +0800 To: multihulls_at_steamradio.com > >Anyone care to comment on the new line of offshore racers from Bret Crowther > > > > the Southern Ocean sailing line? > > THX > >dennis ferreira G'day, Would these be the ones (Raw Nerve) that broke up on their first coastal sail, in moderate air, under delivery rig, then won a design award. Had an alarming tendency to nose dive, then had the hulls completely redesigned, lengthened and rebuilt by Geoff Cruse, at huge cost to the owners? If so, they are now apparently pretty good, (albeit a little narrower for their length and with more sensible relative mast heights), with one of them (Rognatudjuu) winning this year's Brisbane Gladstone, despite being beaten on the 10 mile upwind leg out of Moreton Bay by a 30 footer, and also beating a bunch of monos on a 900 mile reach from Auckland to Noumea. Next most expensive multi in the B/G race cost about 1/10th as much. Brett is to be admired for having the balls to build the first one (at 10m, a dog, now lengthened to 11.7) for himself. Now also narrow for its length and with conservative mast height, it looks much better & seems to go pretty well on Pittwater but is yet to be taken into open water. It will be tested at Easter next year when the Aus Offshore Multi Champs are contested in Sydney. Hopefully Raw Nerve will also be there. Shame Brett's boat's progress was overtaken by the 50's, before the lessons about huge rigs on short boats could be relearnt. To the best of my knowledge no more boats to either design have been built in Aus. Maybe we could also hear what caused the first one to fall apart? Stu? SP? Paul? Anyone but Rob Mundle! Stu engineered them, SP provided the materials, Paul Nudd got the blame for the break up, (wrongly in my opinion and that of anyone who has ever sailed with him), and Rob (journo) was employed by Crowthers to put a positive spin on it all for the media, which may have helped convince the insurance company, but certainly failed to impress any of the Aus multihull sailors. The following is hearsay and may be wrong, but it is all that we have been told so far. The boat was allowed to sit on a sheltered beach in a blow. Nuddy was the skipper at the time. The owner was complicit in the decision to go on the beach and Paul had put his own boat (XL2, Crowther 38, but designed by Lock, not Brett) on the beach many times in worse conditions with no adverse effects. Brett was apparently aware it was on the beach & expressed no concern at the time. The boat broke in 2 a couple of hundred light air miles afterwards. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: RE: [MHml] Re: Cat comments From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Wed, 8 Aug 2001 23:12:07 +0800 To: multihulls_at_steamradio.com G'day, > >I feel your comments regarding our designs are libelous, completely > >untrue, unsubstantiable and completely based on hearsay. Your completely over the top response to my factual, slightly tongue in cheek answers make me wonder just how much more there is to the Raw Nerve debacle. You have not identified any comments of mine which are untrue. You have read them as someone who has something to hide, then picked holes in the weather reports, without actually addressing the real issues regarding my answer. These are: The boat broke, the first two boats were substantially redesigned and rebuilt and Brett's boat, which is similar enough to draw similar conclusions from, was also redesigned and rebuilt after performing poorly in it's original form. Paul Nudd's reputation was damaged in an attempt to find a scapegoat in the RN saga. <To my knowledge you have never sailed on either of these boats and many of your <assertions are simply untrue. I never claimed to have sailed on any of the boats. Which assertions? The only untruths that you have identified were about the weather. Hardly libellous <I do not know what motivated you to make such damaging comments in a public <forum, but I must ask you to withdraw all of your comments or provide evidence <to substantiate them. I was motivated primarily by someone asking a question and you being too timid to answer it. Secondarily, by the walls of silence and bullshit erected when Raw Nerve fell apart, compared to all the "aren't-we-wonderful" hype which preceded it. You making veiled threats and demands and calling me names only makes me more interested in knowing what you have to hide. Prior to giving a talk to the NZ Multihull Assocn on the Aus multi scene, I did ask Brett, privately, what happened . He told me nothing. > >I will post a brief explanation of each Mr. Denney?uninformed statements. And I will point out that except in one (irrelevant) case, my statements are not uninformed. > > >> >>Would these be the ones (Raw Nerve) that broke up on their first coastal >> >>sail, in moderate air, under delivery rig, > > > >The failure of the boat has been independently investigated by a number of >> >>parties, none of whom have attributed any portion of the failure to the > >design. >The result of the investigations was to determine that the > >damage was the >direct result of the grounding, during which time loud > >cracking was heard while >the boat was being repeatedly slammed against > >the beach beam on to the surf in >a storm. This is a trick Paul Nudd has > >never tried with his own boat, and I?>sure it or any other catamaran > >would suffer a similar failure when subjected to >the same treatment. According to most of the people on board (as per personal conversations and various unpublished and published interviews in magazines and newspapers), this is simply untrue. The boat was not "slammed against the beach", there was no "surf" and the owner, skipper and the designer were all quite happy for it to be put on the beach, seeing as the waves were so small. Not surprising, given the short (200m?) fetch. I believe there are some photos of the boat on the beach, taken by a local. If I can track them down, list members can decide for themselves whether there was any "surf" or not. I said it broke up on it's first coastal sail. It did. FWIW my 12m (40') proa (Harry) broke (chafed) it's mooring in a gale yesterday. It was washed up on a sandy beach with a bit more fetch (7,000 miles!), in 40 knot winds and was pounded, beam on, by waves large enough to surf on, which slowly pushed it up the beach. This went on for 3 hours, until the tide turned, leaving it straddling the high water mark. Harry sustained no damage whatsoever. This is an coastal cruising boat which cost $Aus6,000 to build and weighs 650 kgs (1,430 lbs). The waves were far larger than those that damaged Raw Nerve. Given that Harry is all wood and epoxy, and rough as guts, there really is no excuse for a million dollar state of the art boat with 4 crew to anchor it off the beach not to be able to withstand far lower loads. >> >>then won a design award. > > > >Actually two, one for engineering and one for industrial design, and it > >was the first boat of any description to do so, after being thoroughly > >vetted by a panel of independent experts in the field. I said it won a design award. It did. The same "panel of experts" probably would have given an award to Team Phillips after it was abandoned. But at least Adrian Thompson would not have been silly enough to brag about it. > > >> >>Had an alarming tendency to nose dive > > > >The hull did not have an alarming tendency to nose dive any many > >experienced >sailors who sailed on the vessel in its original state > >commented that they felt >the hulls were very good. We did overlook a > >side effect of one of the >innovative features of the design, and that was > >the fact that the curved lower >surface of the airfoil shaped forward beam > >tended to suck the beam into the >water if it was allowed to touch the > >surface. This problem has been corrected >by adding two small pieces of > >aluminium to the lower side of the beam. I said it had an alarming tendency to nosedive. It did. You mentioned the hulls as a possible cause, not me. If they were so good, why change them? Maybe the boat would have to nosedive to get the beam into the water in the first place? > > >> >> then had the hulls completely redesigned > > > >The hulls only had a section added to the centre and the aft 1m of the > >hulls was modified. The deck area forward was also modified to increase > >the freeboard consistent with improved visual appear and the increase hull > >length. Only a new middle, modified stern and modified bow? Sounds pretty complete to me. > > >> >>lengthened and rebuilt by Geoff Cruse, at huge cost to the owners? > > > >The modifications were designed by Crowther Multihulls in consultation > >with the owners, Geoff Cruse has done an excellent job of constructing the > >modifications to Rogntudjuuu, but he was not involved in the modified > >design. In the latest Multihulls magazine, Ian Grant all but states that Geoff redesigned it, based on an interview with Geoff. I asked 5 people to read the article, they all agreed that it says Geoff designed it. My apologies for misconstruing the article. > > >> >>If so, they are now apparently pretty good, (albeit a little narrower for >> >>their length and with more sensible relative mast heights), > > > >Wether the mast height is sensible or not is your own personal opinion, > >but the >owners of both SO50?disagree with you and believe the boats > >would be improved >with taller masts. The mast height was never a problem. So why lengthen both boats? >> >>with one of >> >>them (Rogntudjuuu) winning this year's Brisbane Gladstone, > > > >In a race record time that places the average race speed well into the top > >ten average race speed records in the world and the only boat > >significantly less than 60?o be in the top 20 average race speeds ever > >worldwide, and equal the Fastnet Race Record held by Fujicolor II. To compare the Brisbane/Gladstone with the Fastnet, or any other serious ocean race, is clutching at straws. The BG is an overnight warm water coastal sail, generally with sea breezes, land breezes and associated lulls between the two. Every so often it is an eased sheets blast with a decent breeze up the bum. This was the case this year. Those who have only ever raced up and down the Queensland/northern NSW coast think it is a major event. Those who have completed serious ocean races look on it as a jaunt. > > >> >> despite being beaten on the 10 mile upwind leg out of Moreton Bay by a >> >>30 footer, > > > >You fail to mention that the starting leg was downwind snip I said it was beaten out of the Bay by a 30 footer. It was. To be beaten by a boat a little more than half it's size on a reach is even less convincing. > > Again Rob has taken some >license in describing the weather conditions,snip My point was it beat a bunch of monos to Noumea. It did. I mentioned the monos as a counter to the somewhat desperate publicity claiming it "won" the Auckland Noumea race. > > > > > >While our 10m design is considerably different from the 50?esigns....., > >snip a whole lot of sanctimonious rubbish...with very little signs of > >fatigue on the structure. Enough of the feel good advertising! To compare yourselves with the pioneers is arrogant in the extreme, given that you are experimenting with other people's money. I assumed that because Brett's boat and the 50's were similar, they were both part of the "Southern Ocean sailing line" that Dennis was enquiring about. Given that Raw Nerve and Rogntudjuuu are completely different to the original Southern Ocean 50's, I think it is fair enough to include Brett's boat. I said Brett had balls to have a go. He has. He's got even bigger balls to call his boat Flotsam. Admirable, given the circumstances. >> >>Now also narrow for its >> >>length and with conservative mast height, it looks much better & seems to >> >>go pretty well on Pittwater but is yet to be taken into open water. It >> >>will be tested at Easter next year when the Aus Offshore Multi Champs are >> >>contested in Sydney. Hopefully Raw Nerve will also be there. > > > >Again, this is a completely different design, but the changes we made were > >to counter the excessive weight added by the builder who faired the hulls > >(not Geoff Cruse). We are doing well sailing on Pittwater and > >occasionally offshore. We are currently leading the current series on > >Pittwater and we are also consistently at the head of the fleet (one of > >the most competitive of its type in Australia) every week in a large > >variety of conditions. I would also like to make the rig much taller, but > >we can?afford it. This doesn't stack up. These are the hulls that Geoff Cruse built, yes? I saw them just before they left his factory for your place. They were up to his usual standards. Why not just knock off the excess bog and refair them, rather than spending all that money rebuilding them to carry the bog, unless there was a design fault. They were light enough to lift when I saw them. I said that you were looking good on Pittwater (sheltered waterway just north of Sydney). You are. > > >> >>Shame Brett's boat's progress was overtaken by the 50's, before the lessons >> >>about huge rigs on short boats could be relearnt. > > > >We have learnt many useful lessons, but this is not one of them. There > >are many boats with proportionally larger rigs. Maybe, but they don't get lengthened within a season of being launched. You haven't explained why all three boats were lengthened. My comment on rig heights is certainly not libellous, or to most reasonable people, untrue. > > >> >>Stu engineered them, SP provided the materials, Paul Nudd got the blame >> >>for the >> >>break up, (wrongly in my opinion and that of anyone who has ever sailed >> >>with him), and Rob (journo) was employed by Crowthers to put a positive >> >>spin on it all for the media, which may have helped convince the insurance >> >>company, but certainly failed to impress any of the Aus multihull sailors. > > > >If you have any facts to support your spin on the events then I think you > >should present them, because I cannot see any. I am not placing any spin on events. Apart from the weather in the BG and Noumea, and whether Brett's boat is a Southern Ocean boat, everything I said is correct. Which facts of mine in the above paragraph do you have trouble with? > > >> >>The boat was allowed to sit on a sheltered beach in a blow. Nuddy was the >> >>skipper at the time. The owner was complicit in the decision to go on the >> >>beach and Paul had put his own boat (XL2, Crowther 38, but designed by >> >>Lock, not Brett) on the beach many times in worse conditions with no >> >>adverse effects. Brett was apparently aware it was on the beach & >> >>expressed no concern at the time. The boat broke in 2 a couple of hundred >> >>light air miles afterwards. > > > >I have heard a lot of hearsay that tells a VERY different story, but I > >would >not like to compound lies with more lies, so I just stick to the > >facts that I >know as fact. A pathetic attempt to avoid having to say what really happened. Are you saying that all you know about Raw Nerve on the beach is "hearsay"? Are you saying Brett was not aware it was going on the beach? That the owner was not complicit? If you have some facts different to those generally accepted by the multihull fraternity, let's hear them. > > > >I trust Rob will be man enough to retract is statements in the light of > >some of >these facts that he was clearly unaware of and I hope in the > >future he will >think twice before publishing his conclusions based on > >false premises that >unjustly damage an innocent parties reputation. The only "fact" that I got wrong is that Brett's boat is not of the Southern Ocean line. I am sure Dennis was grateful for the information on a boat which is very similar in many ways. I trust Stu will be man enough to stop hiding behind veiled threats relating to "libel" and come out with the full story on why Raw Nerve broke up and why all three boats were lengthened. No one doubts that sitting on the beach contributed to the problem, the issues are: 1) whether it should have been strong enough to withstand these loads. The designer, the owner, the skipper and the crew all seemed to think it should have been, as a "cruiser racer". 2) Whether it was fair to attempt to ruin Paul's reputation as a professional skipper to cover the Crowther Design Office butts over a design error. 3) Why all three boats were lengthened 4) What other details are being hidden behind Stu's over reactive, aggressive paranoia? Just read Paul's report and seen the photo. Seems like Stu owes us both an apology, or is he still maintaining Paul is a liar, and a perjurer? > > regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Windmill Power From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sat, 25 Aug 2001 22:33:33 +0800 To: multihulls_at_steamradio.com G'day, The one in Malcolm's catalogue was never completed. Arguments between the "let's build it from steel so it never breaks windmill consultant" (who had successfully put a 9m diameter windmill on a 9m mono), and the "let's build it from composites" designer and builder resulted in a fiasco. I think it ended up with a conventional rig. Small world story. Years ago, in England, I built a 9.5m dia 3 bladed windmill for my Iroquois. Drove a 1m dia water prop, and all worked well, but scary, due to running short of money (insurance from a capsized cat) about 10% of the way through the project. Did 6 knots directly into 20 knots of breeze, and as far as I know the rig is still sitting in a shed in Essex, if anyone is interested. At the same time Jim Wilkinson was building his first version 15 miles away, on the next river North. Neither of us knew about the other till his was launched and made the local paper. If anyone in the UK or AYRS talks to Jim, please offer him my congratulations on his new boat. I look forward to hearing how it works, and seeing the specs of the rig and drive train.. Regards, Rob > > One of those has been in Malcolm Tennant's catalogue for lo these many > >years. > > > >Roy Mills > > > > _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Re: windmill propulsion From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Fri, 31 Aug 2001 22:28:25 +0800 To: multihulls_at_steamradio.com > >OTOH, on reaching or broad reaching courses, the windmill disk not > >only converts wind energy to torque, it also acts as a "sail" in its > >own right. If the boat's hulls can offer some leeway resistance, or > >if it carries daggerboards, it can both "sail" and "windmill" at the > >same time, recovering much more energy than the mill can alone. > >Better than a sailboat? I don't think so. Anybody know, for these > >courses? > > > >DAve Culp G'day, There is a small 2 man keelboat (I think) class that races out of Cowes called the redwing. Hull shape is restricrted, anything goes with the rig. Pre war (not sure which one), Lord Brabazon, an eccentric aristocrat with a penchant for trying different tricks in aeroplanes and boats, put an autogyro rig on a Redwing. Canvas blades on steel shafts (his nephew still has these in Cowes, they should be in a museum). No water prop, it worked like a sail, ie upwind was high pressure, down was low, so the rig, with boat attached moved towards the low pressure. Apparently it worked well enough, up, cross and down wind to be banned, although the story gets a bit complex, as one Cowes Week, they lost control, it ran into a bunch of other boats and the spinning blades did a fair bit of damage. This may have caused the banning. When I fitted the windmill to the Iroquois, it was inteneded to be used as an autogyro off the wind, with the propellor and outdrive disconnected. The thought of it speeding up sufficiently to override the controls (no idea if this was possible, but it was ascary thought) meant it never happened. From memory, theory was that as an autogyro, it would reach faster than under sails. It certainly went upwind better under windmill than under sails, and this with a pretty inefficient prop. regards, Rob PS Dave, When are you going to tell the Multihull list about the latest advance in cruising boats? _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Windmill Power - Faster than the wind, directly upwind From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sun, 2 Sep 2001 14:40:47 +0800 To: multihulls_at_steamradio.com G'day, You are right about the Iroquois, and it's rig. However, it should be noted that the windmill was hardly state of the art then much less now.. The air blades (wood and glass, with steel shafts) were pretty light due to the "coning" attachment at the hub. They would now be carbon, and maybe half the weight. They were also slightly different, proven by the different pitched whistle each one made. Not a surprise as they tapered in 2 directions and twisted non linearly. The gear boxes were fairly efficient, but could be better, the drive shafts were alloy and the round alloy mast had a bit of rigging on it. It also would now be carbon, and foil shaped. The biggest loss was the 1m (40") diameter propellor. This had fibreglass blades, made on the "looks right, let's hope it is" principle and was originally pitch controlled by an external cable which my calculations showed would always be under tension. It wasn't, and got caught in the propellor, fortunately at very low revs. After this, the blades were fixed in position, thus giving all the negatives of both fixed pitch and variable pitch. The amount of water this prop shoved around was very impressive. Just a shame so much of it went sideways instead of backwards. So, a decent prop would have made it much quicker. The rig was designed to spin at 180 rpm and guesstimates of speed (boat drag was never tested) were about 13 knots, directly into the wind. The highest we ever took it was 105 rpm (through some interesting vibration modes), at which time we achieved 6 knots dead upwind. This was, in my opinion, very close to the structural limit, but nowhere near the performance limit. The answer to your question? According to these numbers it would be no contest, the windmill would bolt in. The numbers were not mine, they were supplied by a very clever engineer who had designed, built, installed and documented a windmill rig on a 19' mono. They were checked by various other knowledgable people, and were generally considered to be correct. In an attempt to answer your question, I started to build a 5m (16') version with 2 fixed air blades, optimised for sailing into 20 knots of breeze, driving a fixed pitch prop. The hulls were 2 layers of kevlar/epoxy, inflated. Incredibly stiff at 1.7 atmospheres (25 psi) pressure, but burst soon after, very nearly taking out my ear drums and the garage door, at which stage I lost interest. Regards, Rob > > > >At 10:28 PM +0800 8/31/01, Rob Denney wrote: >> >>When I fitted the windmill to the Iroquois... snip... It certainly >> >>went upwind better under windmill than under sails, and this with a >> >>pretty inefficient prop. > > > >As I recall, the Iroquois is a 1960's cat. Fairly baggy dacron sails, > >not much tension in the headstay, non-rotating mast, etc. From > >memory, d'you think the windmill version would beat a more modern > >cat, to windward? > > > >Dave > > > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Harrigami From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sat, 8 Sep 2001 13:33:47 +0800 To: multihulls_at_steamradio.com G'day, Harrigami's (10.5m/35' traillerable cruising proa) hulls are virtually structurally complete. 280 hours work , $Aus5,000 ($US2,600) of materials weighing 400 kgs (880 lbs). "Just" the fitting out to go. Photos and a progress report have been emailed. Anyone who should have got them but didn't, or wants them, please let me know. regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Re: Harrigami Update 2 From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sun, 9 Sep 2001 10:37:09 +0800 To: multihulls_at_steamradio.com G'day, No problem. In a couple of days so I can send to everyone at once. Regards, Rob > >Hi Rob > > > >Sorry for the bother - but would you resend "Harrigami Update 2" > > > >I did reeive it - but somehow it got blown away. > > > >Thx ever so much > > > >Tom Henry > > > > > >Rob Denney wrote: >> >> G'day, >> >> >> >> Harrigami's (10.5m/35' traillerable cruising proa) hulls are virtually >> >> structurally complete. 280 hours work , $Aus5,000 ($US2,600) of materials >> >> weighing 400 kgs (880 lbs). "Just" the fitting out to go. >> >> >> >> Photos and a progress report have been emailed. Anyone who should have got >> >> them but didn't, or wants them, please let me know. >> >> >> >> regards, >> >> >> >> Rob >> >> >> >> >> >> >> >> _______________________________________________ >> >> Multihulls mailing list >> >> Multihulls_at_steamradio.com >> >> http://www.steamradio.com/mailman/listinfo/multihulls >> >> >> >> >> >> > > > > > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] re: Sections for Proa Boards and Rudders (Tom Speer) From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sat, 22 Sep 2001 22:48:59 +0800 To: multihulls_at_steamradio.com > >I hoped it would be useful. It was an interesting problem. > > > >I wish there was a way to finesse that rudder problem, though. It's a tough > >one. > > > >Cheers, > > > >Tom Speer G'day, Fascinating stuff. Thank you very much. A couple of questions: 1) Was this just an intellectual challenge, or are you thinking seriously about proas. If the former, it's admirable, and much appreciated. If the latter (I hope it is), could we have some details, please. 2) Are there any plans afoot for tank testing to validate the designs? 3) How would these shapes for a solid wing (assuming some camber control) compare with a sail/mast/jib combination? Re rudders: From my experience trying all the usual rudder solutions (except fixed slotted foils, which we will be testing this summer) the solution is simple: 360 degree rotation, with rudders large enough to supply sufficient sideforce to eliminate the need for other water foils. This not only moves the centre of resistance aft on each shunt, it gives heaps of control at low speeds, such as exiting a shunt. They also have the advantage of being able to steer the boat sideways to some degree. Very handy entering and leaving tight spots under engine, but as yet not proven to be advantagous going upwind (also on the list for this summer). Any comments on the efficiency of variable angle of attack symmetric foils vs fixed angle of attack assymetric foils would be much appreciated. 360 degree rudders are not only highly efficient steerers and leeway preventers, they are very easy to use. They rotate automatically during a shunt as soon as the boat starts to move in the new direction. Combined with a rig which partially does the same, shunting becomes a pretty effortless chore. Thanks again. Regards, Rob > > > >me_at_tspeer.com > >http://www.tspeer.com > > > > > > > >_______________________________________________ > >Multihulls mailing list > >Multihulls_at_steamradio.com > >http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Emmanuel Roche/60' proa From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Wed, 26 Sep 2001 08:22:21 +0800 To: proa_file_at_yahoogroups.com, multihulls_at_steamradio.com G'day, Not sure if Emmanuel is on the list, but he has some information on a 60' proa in France, which I would like to know more about. Unfortunately, I cannot reach him through his email address. You out there Emmanuel? Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Why a 40 something might work From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Wed, 10 Oct 2001 08:01:44 +0800 To: multihulls_at_steamradio.com G'day, Brad asks for the negative impacts of his "cool boat" list. The main negative is that they do not encourage anything other than what is currently accepted, and that this, according to the Spinlock forum costs 220k pounds sterling, $US330k, which is far more than most of us have. Buying one second hand and beating up the local mono and cruising multi fleet is fun, but not what the rule is about. I have not got any numbers, but suspect that the most expensive part of a multihull over it's racing life is not the high tech (carbon/nomex) hulls but the purchase and maintenance on the rig, deck gear and sails. Nothing in Brad's list or the Spinlock forum addresses this. Not surprising, as most of the forum sponsors sell this gear. Two specific points: 1) Limiting length primarily limits top speed and diagonal stability. Leave all else the same and a 12m cat with 14m hulls (maybe 1m added each end) will be faster, drier, safer and in some sailing scenarios will see lower loads. 2) A specified hull volume means higher all up weight and cost and makes for more resistance, thus more loads, bigger sails, rigs etc. It does not make the boat any safer. If you specify headroom, berths, toilet and galley, what is the purpose of the rest of the volume above what is fastest? The reason why, in my opinion, a 40' racer with (very dubious) cruising potential will not be acceptable is that it will be beaten by 40' racers without that potential, and owners forking out a quarter of a million sterling to win races will not want to start with a handicap. My quick and dirty cool boat wish list (feel free to point out it's negatives): As long and wide as structural and other limits (container, marina, trailer) allow. Low cost to build, maintain and sail. Low cost to me is $Aus15,000 (5,000 sterling) to go racing in a self built 40 footer. Maybe double this for ocean racing capability. Easy to build, maintain and sail. Maximum 400 hours to build, without expensive tools or moulds, capable of being sailed singlehanded in a confined space, little or no deck gear, under canvassed with a small rig/light boat/high power to weight mindset. Sheltered, out of the action place for wife and kids to sit and watch the action, without being in the way, plus space and facilities to go comfortably cruising for the rest of the weekend immediately the finish line is crossed. Faster than "conventional" boats of similar cost or space. Competitive with boats of similar length. I suspect that there would be far more potential owners for boats trying to achieve these criteria than for a Spinlock type boat. Regards, Rob PS The Spinlock Forum lists water absorption as a problem for strip planked, epoxy sheather boats. Built properly, this does not happen. Verbatim (12m Crowther tri, most successful racing multi in Aus sailing history) is long grain balsa with 300 gsm (9 oz) kevlar each side. After 17 years of hard sailing and some pretty casual owners, the planking is, to the best of my knowledge, as dry as when it was built. _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Why a 40 something might work From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Thu, 11 Oct 2001 10:56:38 +0800 To: multihulls_at_steamradio.com G'day, > >Rob, > >You make a number of good points, and didn't mention proas once :-) Thanks, I was saving them for the inevitable (I thought) shouts of "It can't be done". If people accept that my "cool boat wish list" is possible, I'm stuffed if i know why people spend so much on overpowered, overpriced, expensive to maintain, potentially dangerous boats, then complain about the cost. Afterburner would have to have been, in it's previous life, the epitome of everything I was denigrating. However, Alister is a great bloke, who works hard and got real joy out of owning it and buying improved performance. Even got a buzz out of doing his own scrubbing off, sanding and antifouling. It was almost enjoyable being beaten by him. If this is how he wants to spend his money, more power to him. You got a bargain basement priced machine on which you have learnt more about fast sailing than you could have in any other way. Judging from your posts, you are also having a lot of fun learning. It's your money, spend it how you like. I guess my post was aimed at those who complain about the cost of their sailing, and assume there is no alternative. > >Grand Prix sails last a season or two, and cost a lot. You can go with > >longer life Spectra and get beat by the guys with the expensive North 3DL > >sails. I'm gaining experience with this type of maintenance cost. All I > >did was buy one second hand to beat up the local mono and cruising multi > >fleet. As I said, great fun, but not what the Spinlock boys are trying to get you to do. Incidentally, and despite the above, if Nuddy can't make the Transpac, and/or you think you could tolerate 2 antipodean hull flyers, I'd sacrifice my left bollock to sail a fast multi in this race. > >How do you make a rule that doesn't favor : > > a. the guy who spends the most money? You don't. Drawing boats out of a hat (tricky concept, but you know what I mean) for each race works at one level, but the rich guy buys coaching, time to practise, weather information, etc so is always going to start out ahead. Only solution is to hope he is the kind of guy who shouts the bar at the end, or, like Alister Afterburner, gives away his old sails and gear to the "trying hards" further down the fleet. Claiming races don't stop the rich guys getting the best boats. In fact, lots of yacht racing looks like a claiming rule being abused by rich guys. Spend millions on a boat, win some races, and sell it for thousands. Then go and repeat the exercise, with a new boat which is barely different to the old one. > > b. the professional crew? Sail singlehanded. Prof crews come in so many guises they are impossible to avoid. Alternatively, employ some. > > c. the designer who works on beating the rule? Buy your plans from him! Better is to have a simple rule so the only combatants are the sailors and nature. Soon puts half the marine industry out of business, so don't waste time suggesting it. A box rule which gets round the high cost of maintenance could be to use a shipping container as the box. No component greater than 12m (40'), all components to go in the box. Encourage the lightly loaded, small rig end of things. Schooners would probably balls it up. To make it expensive, could have a second class where joins to hulls and masts are allowed. Anyone care to venture what the fast boats would look like? > > > >I guess owner helmed 1 designs are as close as you get. Owner driving crewed boats is about getting the pbo (poor bloody owner) involved. It is nothing to do with making it more even. A blind neophyte steering with Team NZ trimming, calling tactics and telling him what to do will clean up any amateur team. These discussions always seem to grow to include everyone's goals. You need to clearly define your targeted participant, and stick to that definition, not try and include everyone. I agree with Rob's points. A $330k entry boat fleet is not going to be a sudden success just because you can sleep on it, unless you happen to know that there is a market demand for it. It'll cost another $50k a year to campaign. It should appeal to people for whom Open 60's are too much, and have this much disposable income. I just don't know how many of these people there are. There are a few (quite a few, actually), but none of them are prepared to start behind the 8 ball by sailing a cruiser when there is the slightest chance that one of the opposition will have a racer. With this much money to spend (burn?) you buy/charter a seperate boat for cruising, and do it properly. There is more to cruising than sleepability. 6 people could sleep on the Spinlock boat, but I bet they couldn't live on it for much more than an afternoon. Sailing would be miserable, unless you were the helmsman. Either wet in the cockpit, exposed on the tramp, or cramped and dark down below. Powered down enough for it to be enjoyable for any length of time, and it becomes slow, in many conditions. Why bother? > > Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] faster cruising cats From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sun, 21 Oct 2001 09:01:05 +0800 To: multihulls_at_steamradio.com > G'day, The only boat i can think of in recent years that fits this description is Tusk, a Grainger Alfresco design owned and built by Gary Martin. The capsize occurred under spinnaker and from memory was attributable to crew error during or just after a gybe. It was pretty windy, from memory this was the race in which XL2 broke the record. Tusk was refitted and has since cruised around most of Australia without incident. I disagree with your logic. There will always be a limit to hull FORM speed. It is not particularly relevant how much sail the boat "can" carry to reach this limit. What is relevant is how much it "is" carrying and how strong the wind is. Given enough wind, any boat could be capsized, even under bare poles. If Tusk had a smaller rig and was heavier, but the wind had been stronger, it still would have capsized. While I agree that there is more to speed than just weight and sail area, for basic speed comparisons of cruising boats, they are the best place to start, assuming you can get accurate numbers. This is a big assumption. Regards, Rob > I am not convinced comparing weights and sail areas is the key for speed. > > Example is a very light cat around 40' designed by a now very prominent > designer and owned by a sailmaker who kept adding area to improve the speed. > In a Brisbane to Gladstone it did not even get out of the bay before going > end over. Apparently the hull FORM did not want to go any faster. > > Ross Turner > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] faster cruising cats From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sun, 21 Oct 2001 14:14:41 +0800 To: multihulls_at_steamradio.com > G'day, No need to be sorry. The original comment was about sail area and weight being better performance indicators than top speeds quoted by owners or designers. It was about assessing the speed of large cruising cats, not small trailer tris, where waterline length is obviously going to be a limit. I still think it is a better indication, as the following story may attest. That day, in full racing trim on XL2 I don't think we exceeded 22 knots (Paul?) in the bay. We left it alongside Australia's Child, so presumably they did not either. XL2 is a 3 ton, 38' cat with a 58' mast, big roach main and when we left the bay, large spinnaker. Aus Child was a 40' racing tri, a bit lighter, with a bit more sail area. Both boats were being pushed as hard as we knew how, with sheets regularly eased as hulls flew. From memory, I don't think we reached 25 knots throughout the big seas, big wind, best sail I have ever had, broad reach under full rag up the coast that afternoon and night. Our top speed for the race was 27 knots, hit for a second or so down a perfect wave approaching Gladstone. I have raced a few miles on both boats (Sydney Hobart, Bris Gladstone etc) and only rarely reached 25 knots in perfect conditions with big following waves, big spinnaker and alert racing crew. Coral Coaster is a 33' (I think), plywood, full bridge deck cruising cat with suitable sail area, displacement and accommodation. For you to have gone faster than the 2 fastest boats in Australia at the time, means that you have one hell of a boat and should be congratulated on it's performance. Or that weight and sail area are a better indication of a boat's likely cruising speed than the speeds quoted by owners or designers. Regards, Rob > Sorry Rob to disagree so strongly with your statement re performance. > All boats CAN be capsized that is not the argument here. > A TT680 tends to have a limit of about 12knots but the TT720 goes way beyond > that. > The hull form of the 680 is different to the lengthened 720. The 680 was > great in light airs as the speed was below the hull speed. The turned up > stern was the limiting factor. Come the 720 and things improved so far as > speed goes. > The J5 has a speed hump of 5.7 knots and is very hard to exceed this to > windward. The flat aft sections allow the J5 to reach 12 knots regularly and > far exceed this at other times. > Hull form has some bearing on performance. > > By the way on Coral Coaster we reached 25 knots the morning TUSK capsized > and we were not lifting a hull. Lorraine was preparing dinner! > > Ross Turner > > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Design competition From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Wed, 31 Oct 2001 10:07:16 +0800 To: multihulls_at_steamradio.com > G'day, An excellent, though difficult to achieve, set of criteria for what should be a very usable boat. Here's hoping the judges are as broadminded as they appear to be! regards, Rob > Hi, > > > Norwegian Multihull Ass. have started a multihull design competition, open > for everybody. > > You can read more about it here: > > http://www.flerskrog.org/Flerskrog/design%2026_10_01.pdf > > Or follow the link from the homepage at: > > http://www.flerskrog.org/ > > > Fame and fortune (US$ 1000) to be won :-) > > > Disclaimer: I'm a member of the NFS (Norwegian multihull ass.), but dont > have anything > what so ever to do with the competition. Dont know anything more than > whats said in the PDF > file. Dont intend to enter the competition etc. etc.. > > > > Mvh > > Rolf Nilsen mailto:rolf_at_etv.no Telefon: 71 19 19 00 > Prosjektleder http://www.etv.no Telefaks: 71 19 19 01 > > --- StripMime Report -- processed MIME parts --- > multipart/alternative > text/plain (text body -- kept) > text/html > --- > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] faster cruising From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Thu, 1 Nov 2001 22:02:32 +0800 To: multihulls_at_steamradio.com Hope this is not to far off topic, but this has bean on my mind lately. My > desire is for a Catamaran that would fit in the "40 something" class. Ross > Hobson mentions a boat in cruising mode, I am wondering if a boat can be > designed that would have two modes of operation racing and cruising. The > racing mode would be light and sit on top of the water, like my Inter 20. In > cruising mode the hull would operate in displacement mode. > > Something like a stretched out Shuttle 31 with anorexia. G'day, By far the easiest type of boat to achieve real 2 mode sailing on is a Pacific proa with the rig, controls and water foils in the lee hull and the accommodation in the weather hull. Include a semi self supporting rig (keel stepped, but with stays to the windward end of the beams) and it is a relatively simple task to swap windward hulls, especially if you could straddle a dock arm in a marina. Cat or tri hulls and rigs optimised for racing will be a pretty sad proposition if loaded up and fitted out for cruising. A proa with a large, heavy windward hull will be slower than with a minimal stripped out one, but will still be a potent cruiser, and one on which the wife will not be terrified during every maneuver. As for speed, a Pac proa will be maybe 1/2 the weight of a comparable length tri, (it has fewer components, and sees much less stress) so will be just as quick with a smaller rig. It will cost way less than 1/2 as much, need fewer crew and be cheaper to maintain. It will also be far safer in both race and cruise mode. On the down side it will look peculiar and be a little slower to tack until you get used to it. Probably won't appeal to those who like to impress people with the performance possibilities and cost of their car(s), but for someone wanting to race competitively and cruise comfortably without breaking the bank, they have a lot of potential. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Zazen Links From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sat, 3 Nov 2001 23:29:06 +0800 To: multihulls_at_steamradio.com > G'day, Got to disagree with, or at least elaborate on your comments. 1) There are numerous options for reducing chandlery costs, particularly on cruising boats. Use a smaller rig. Simplify the rig. Use a bit more time or muscle for trimming. Do not expect your boat to look like a piece of exotic furniture. Use non marine items. 2) Chandlery is fairly priced for what it is. Lewmar and Ronstan (maybe others as well, I don't know) both live on a financial knife edge. They are both efficient companies. If yachties did not insist on polished stainless, minimum weight, minimum friction, extensively advertised fittings available over the counter at shops all round the country, fitting out would be far cheaper. Spending a hundred quid to save a few grammes on a roller bearing block to save a little bit of winching effort, then taking the kitchen sink on a day cruise, indicates, to me, distorted values. Or spending zillions on a roller bearing mainsheet track, plus winches, high tech rope and state of the art jammers to adjust the sheeting angle, then cleating it and forgetting it "cos you're cruising". There are many other examples on modern multis. 2) Skilled labour in this part of the world (Australia and New Zealand) is highly skilled, honest, hard working and cheap. I know about a dozen free lance builders who work for $Aus25 ($US12.50, 9 quid) an hour, supply their own tools and turn out first class product. The world's best charge their labour, including shed, at around $60 per hour, and are lucky to make money. McConnaghy, Ulrich, Cookson are not wealthy men. They all work in a business where one good stuff up sends you broke. 3) The problem with most dissatisfied boat owners is not that they are optimists, but that they are dishonest with themselves. How people smart enough to accumulate hundreds of thousands of dollars can get 10 quotes for similar amounts, then accept one 15% lower and not expect it to all end in tears is a mystery to me, yet it happens with monotonous regularity. Another example is those who spend a few hours compiling a list of what will go into the project, then get a surprise because they have missed so much out. This is lousy planning, not optimism. If you list every item in the boat, it's cost and the time and cost to fit it, the boat will come in spot on budget. Further self delusion is piling junk onto boats, knowing full well that it will slow them down. This junk is not only cruising gear. It starts when owners want a fit out on a par with a 5 star hotel. This adds to the need for a big expensive rig. Expensive multihulls cost more because owners feel the need to fit them out in style, from end to end, then add a show room finish to acres of exterior, much of it never seen when the boat is sailing, and only a small percentage actually adding to the speed potential. 4) There are half a dozen production multihull builders in Aus. Apart from Seawind most of them come and go with the economic cycle. There are hundreds, maybe thousands of cruising multis, the vast majority built by their owners, frequently with the above freelances helping. The guys who are serious usually get sailing in 12-24 months. The ones in a hurry in less than 6. Many of them cruise for a year or two, then sell their boats, at the moment pretty near covering their building costs, including labour. The majority of these builders talk fondly about their boatbuilding experiences. Some of them even do it more than once. Most of the freelances started by building boats for themselves and enjoyed it enough to look for work helping others. With a realistic approach, the right plans, advice and materials, it is usually a lot of fun. That it is immensely rewarding goes without saying. The cost blow outs start when owners start to look for the last 5 percent of performance for a given length. It is far cheaper to achieve the added performance by going longer. That is, take a 35' cat with 20' beam and 45' mast and extend the hulls by 3' each end. Don't extend the beam, don't enlarge the rig, don't put a double stateroom in the extra space. This will improve performance in most cruising conditions by more than adding another 6' to the mast, and as you say, the hulls are cheap. Problem is, these boats don't, under current fashion rules, look like a million dollars. It is even cheaper to say to hell with the last 5% and to go 10 knots instead of 10.5. 5) It is much harder fitting out a boat than to build the hulls. If you have the space to fit out a boat, you have the space to build it. If you know how to turn on handyman type power tools, are prepared to swap watching TV for working on your boat and aren't worried about a showroom finish, you have the ability and the time as well. 6) Boats are cheap. Luxury fit out, highly stressed rigs and some people's need to either go faster than, or to look as if they go faster than everyone else is what adds the money. Viability of owning and/or building a boat is about attitude, not cost. Regards, Rob > Interesting comments about build costs. > > I have an adage that all sailors are optimists. This is never more true than when they > build boats. > > Although it seems crazy the great big hulls are the easy and cheap bit. Chandlery is > crazy money for what it is and so called "skilled" labour (it rarely is) can be crazy as well. > > On the other hand, few people have the facility to produce the large bits themselves, > but quite a number have the ability and facilities to complete something like this. > This sweat labour is where you can save huge amounts of money. > > On the numbers you quote Dale's prices are still well low compared to Greene Marine > or Dave Irving .... for a shell. Bader's prices are also pretty keen ... also for a _shell_. > > Noone should ever kid themself that a boat will ever be cheap and as I have said before > I would never recommend building a boat to anyone. Not that it can't or shouldn't be done > just that I would never recommend it to anyone. > > As anyone who has ever managed to finish will attest it takes lots more time and money > than you first thought but _huge_ amounts more dedication. > > Gary > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Zazen Links From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sun, 4 Nov 2001 23:15:46 +0800 To: multihulls_at_steamradio.com > Paul wrote > Owning a boat is not cheap but it can be either expensive or VERY > expensive, > again it is a matter of attitude and what you are prepared to put up with. Cheap is relative, of course. It would be interesting to compare ownership costs with say, maintaining a weekend/holiday shack on the beach, chartering for a fortnight each year, renting a house for a year or as a percentage of the average wage. Be interesting to see a breakdown of your (and other owner's) costs, and then break it down into racing, cruising, convenience (marina fees instead of a mooring and a dinghy, for example) and non structural cosmetics. With a suitable attitude, owning a boat and building it can be cheap. > Paul: > Regarding building, I agree with Gary, > I would never recommend building a boat to anyone. > But if you can get Rob to do it for you, > or organise it for you using $A25/hour skilled labour . . . . . . > I just wish I could get one of Rob's dozen to do some repairs/maintenance > on XL2! You sound sceptical? If you really want some work done, give Glen (a mutual friend and itinerant boat builder) a call, although repairs/maintenance on a foam/kevlar boat in expensive Sydney is much less appealing than building a strip planked one in tropical Queensland, so his rates may be a little higher. On the other hand, he owes you enough favours for taking him sailing that he might charge less... If Glen is busy or not broke he will have the contact details of others (probably Queensland based) who aren't, or I can give you some names. Alternatively, drop into Monty's, Samson's or Shaun's (boatbuilding parks occupied by owner builders) with a carton of beer on Sunday evening and ask around about who is competent and looking for work. Or ask one of the designers (Chamberlin, Snell, Schionning, etc) or epoxy companies who sell plans/materials for amateur boat builders. They will all know highly competent builders who are looking for work so they can finish their own boats. As for getting me to do it, probably not. I don't build boats for others unless they are interesting projects, (W for example) for owners whose attitudes are sympathetic to mine, and who are willing to pay for a radical approach combined with dubious accuracy and an industrial finish above the waterline. These owners are suitably rare, but anyone who feels qualified is welcome to get in touch! For the others, I'm happy to provide names of suitable builders. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Zazen Links From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sun, 4 Nov 2001 23:15:59 +0800 To: multihulls_at_steamradio.com > Rob said: > >> Chandlery is fairly priced for what it is. > > I remain unconvinced because: > > a) We have had a number of items fabricated by a (profitable) local engineering firm > for less money (and a more appropriate function). > > b) Chay Blythe (a good Scot for whom profit really is a religion) made all his own > blocks and jammers for the BT boats. You can buy these from Atlantic Spars. From > memory a 12 tonne SWL block was about 80 GBP which makes local product look crazy. > The cheeks are flame cut from alloy on the CNC bed at DML in Plymouth. The jammers > are simply designed to hold the laods while the lines are transferred between the > horn cleats that back them up and the winches. None (zero) of these items broke > going round the world. These are quality items to look at as well. Very pretty. > > c) Rutgersen in Sweden (one of the most expensive countries in the world) make > really nice high load blocks for less than anything else local. Amusingly the > plain bearings have about the same friction as ball race ones when under load. > Rutgersens high load models have roller bearings and are still waaay lower than > the opposition. And they are made in Sweden ! a) and b) reinforce what i said. The costs of manufacturing are the same for everyone, > although Lewmar (for example) also have to pay R&D and testing costs (which are quite > substantial) but gain over the local engineering shop by having some economies of scale. However, Lewmar sell to their world wide agents, who have to pay staff to handle them, finance advertising campaigns and pay interest on the cost of stock sitting waiting for impatient boat owners. So they add a 50% (or whatever) margin before selling them to your local shop who have to pay their overheads, their expensive staff to be there on Sundays when boat owners want to buy and the financial costs of stocking 10 varieties of the same item because owners expect to be able to choose between blocks with/without beckets, swivels, ball bearings, etc etc. So they add 50% as well. Lewmar Head Office can't sell direct to you because all the shop keepers (rightly) get pissed off. This is why chandlery and most other retail items are expensive compared to the cost of production. Rutgerson I don't know much about, but they don't advertise (much) and they aren't stocked at my friendly chandlery so probably save a lot on the middlemen. I spent a bit of time at Lewmar trying to sell them carbon blocks and winch handles. They run a very tight, efficient and impressive operation, as do Ronstan. On jammers: back in the days when my boats needed winches, I built my own jammers from commercial aluminium 50mm x 12mm bar, using a hacksaw and a file. Very simple, very efficient, unbreakable. Would have cost a dollar or so each (for doubles!) if it wasn't scrap alloy. Looked agricultural and weren't easily releasable under load, though it was possible. Worked a treat. A workable copy of Spinlock's best could be built almost as easily, although I probably wouldn't load it to their breaking loads, and it may be a bit harsher on rope covers (easy enough to replace occasionally). > > > Rob also said: >> Another example is those who spend a few hours compiling a list of >> what will go into the project, then get a surprise because they have >> missed so much out. This is lousy planning, not optimism. If you >> list every item in the boat, it's cost and the time and cost to fit >> it, the boat will come in spot on budget. > > This is of course sound advice assuming: > > a) You really know everything that should go into the boat. (You have probably > built a few before if you do) Keeping it simple helps, as does doing lots of homework. It amazes me how many people spend so little time and effort on the basics before embarking on one of the major projects in their lives. Especially when these basics are mentioned so often by people who ignored them. I think it is in the same category as not fitting escape hatches to multis for when they capsize. Delusion rather than optimism. > > b) Things end up costing what they "should" (were quoted at etc.). I can provide > a very long list of builders, quite a number of whom are professional, who have > been subject to cost overruns. In this part of the world for example it is very > difficult to get a quote. Most people will only provide an estimate. Without knowing details, it is difficult to comment, but the builders I know of who had cost over runs were either guilty of under quoting (see "10 identical quotes and accepting the 11th because it is 15% under") or found that the owners understanding of the quote was different to theirs. Depending on who wrote the contract, depends on who takes the fall. If price is going to be important in a project i always ask for a written quote, and, also in writing, that it be subject to a month's warning before any increase. I've yet to be disappointed. Buying from anyone who won't provide a quote (detailed enough to be binding on both parties) is folly. Of course, preparing such a quote can be expensive. Owners prefer to delude themselves that the "estimate" will work out cheaper than paying for the cost of preparing a proper quote. > c) Things fit the way they should. This is actually fairly rare for a lot of projects. Again, lack of planning. If builders/owners/designers spent as much time working out how things fit as they do on the merits of different, near identical products and materials, they would rarely be disappointed. > > In this part of the world fitting out a boat in your yard isn;t much of an option. > Its hard enough doing the work without the serious grief from the neighbours and the > council as well. On the other hand boats float and there are plenty of boatyards and > marinas where you can do a fitout. Almost none of these allow on site building of hulls. Long time (20 years) since I built boats in the UK. First was on a vacant block next to a coal shed in the middle of Brightlingsea (filthy), the second in Woolston in return for a backhander to the caretaker (nervous making as I was always expecting to be evicted). No idea of the current situation there, but here there is plenty of industrial space available, albeit not necessarily cheaply. For example, I am currently building in a corner of a grain storage shed, next to an (occasionally) very noisy pea splitting plant. However, this was not my point. although I see now it was yours. I was referring to boat building per se, not the trials and tribulations of living in suburbia. regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Zazen Links From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Mon, 5 Nov 2001 18:31:47 +0800 To: multihulls_at_steamradio.com > Paul, > > When Rob says "...I don't build boats for others unless they are > interesting projects, (W for example) for owners whose attitudes are > sympathetic to mine, ..." > > I think he means "proa" :-) > > Bill Gibbs > Afterburner/Sonrisa (for sale) G'day, Not at all. W is a cat, albeit a pretty extraordinary one. Even more extraordinary now that the owner has found time to play with it. Truth is, I am not fond of hard work and mostly don't need the money, so any physical labour has to be very interesting to get me going. Even a proa would have to be pretty different if I was to actually get sticky building it for someone else. Non physical labour, sailing and project management are very different ball games. Happy to think about, sail on, discuss or organise anything! Just tried to look at an article on W, (www://insidemultihulls.com/) using Netscape. Some porno crap comes up instead. Any of you computer geniuses know how to get around this. Answers offlist, please. And no, this is not just a ploy to get the deviates to have a look at W... Re Roy, Rick and fairing I did not invent bead fairing. I learnt about it from Arnie Duckworth (inventor of DuraKore) who is exceptionally innovative, but who also was not averse to borrowing other people's ideas. I daresay he found out about it from Roy. Any chance of posting the text of Handel, Roy? Be amusing and educational. In the unlikely event I am ever responsible for mass producing Harrigamis, they will be finished to whatever standard the owner stipulates, which will be explicitly defined in the quote. Finish your boats to whatever standard pleases you.. It would be boring if they were all the same. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] re: Blocks & Chandlery From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Wed, 7 Nov 2001 11:13:52 +0800 To: multihulls_at_steamradio.com > G'day, Innovation is what was demonstrated by the original Lewmar,Antal,Ronstan, Harken,Frederiksen (LARHF) people, supplying something original and different to fulfill a market need. Combined with a lotof hard work and a bit of luck, it will generally make money. Copying someone else and trying to survive on smaller margins or by eliminating your competitors middlemen is not innovation. It is what many of the e businesses tried to do, and failed miserably. Based on what happens in other industries, the following would occur when Pearce Blocks Direct Sales (far better quality than anything else available if his boat is anything to go by) got going: First, PBDS would sell a few blocks of limited sizes and types, not enough to worry LAHRF. Business would look good, they may expand a little, but would still only be selling a smallish range. Eventually LARHF would feel the pinch. They would then do one of three things. 1) Make Gary an offer he couldn't refuse, and close PBDS down (the Mafia/Microsoft method). 2) Start their own companies, with LAHRF backing but a different name, making exactly the same products as PB, selling direct in exactly the same way, but not being hampered by PB's limited capital so able to work on smaller, or negative margins until PB is forced to go under, complaining all the while about lack of customer support. The LAHRF copy companies stop operating the next day. (The British Airways method). 3) If neither of the above worked, LAHRF would say to hell with the middlemen and start selling named product direct. In the ensuing chaos chandlers would go bust, a lot of boat owners (who consider the cost of chandlery well worth the price, if it means they can buy it on Sunday and not lose a days sailing) would be pissed off and PBDS would go broke overnight. Shortly afterwards, Lo and behold, LARHF would stop selling direct, chandlers would reappear and boat owners would start whinging about the cost of chandlery again. Not sure of any international examples (know a few in Aus) of this, probably because the first 2 are so effective. If you want to save on the cost of chandlery, be innovative. Use rigs or designs that don't need it. Ballestron rigs (which I think are fantastic, but don't sell) are an excellent example. Unstayed, they may save even more money. On a more mundane level: Replace travellers and associated blocks, jammers and winches with a block at each end of the aft beam with a mainsheet to each one. Little more work to trim, but far less chandlery. Safer, too. Think about what you need, rather than blindly following the racing guys. Regards, Rob PS Option 1 may not adequately explain all of M/softs techniques. Regardless, please do not waste space with a discussion of Gates and his business practises.. > > > All good points, but also seemingly a good arena for > an e-business: Widely disbursed market, easily > shipped high value product, traditional competition is > entrenched in brick and mortar and trad advertising > overhead, well educated and very well inter-connected > market to maximize word of mouth... I don't know that > you do need 'massive' advertising for this kind of a > venture. Regarding panache, if you can deliver the > same block for 40% of the (retail) cost, can't you > deliver a better block for 50% or 60%? If you > actually win a magazine shoot out or something > similar, your stuff would become the cool new thing, no? Kevin _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Harrigami launched and weighed From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Tue, 11 Dec 2001 22:38:19 +0800 To: multihulls_at_steamradio.com CC: Multihull Racing <multihullracing_at_yahoogroups.com>, multihull_boatbuilder_at_yahoogroups.com, proa_file_at_yahoogroups.com G'day, Launched Harrigami last week after a lot of hassle with the trailer/folding system. Trailled easily behind my 1.8 litre 4 cylinder car. Took 3 hours to unfold and launch, a bit less to retrieve and pack up. Will be a lot quicker when all the temporary tie downs etc become permanent and I stop worrying about things which might fail. Sailed well (don't they all, in light air!) and shunted easily despite the cut down jib being too small to properly balance the main. The halyard lock (Ronstan cam cleat) could not handle the loads so the sail was aborted after a couple of hours. No reason to believe it will not sail at least as well as Harry (12m/40' predecessor), once the bugs are out. Now back in the shed for completion of the interior and painting in the sponsors colours. More about this later. Should be back in the water just after Xmas. Car and loaded trailer weighed 2080 kgs (2 and a bit tons), car and unloadd trailer 1560kgs (1.5 tons). So, boat with all sailing gear weighs 520 kgs (1,144 lbs). Weights accurate within 20 kgs according to the weighbridge operator. Paint and the rest of the interior (galley, double bunk, table and chairs, enough shelf space for 2 for a weekend, toilet) will maybe add another 30 kgs/66 lbs, giving all up weight of 550 kgs/1,210 lbs. Harrigami (Harry + origami) is a 10.5m/35' weight to windward Pacific proa built from strip planked pawlonia (chinese hardwood), epoxy and glass. It has a semi unstayed mast, ballestron rig and twin rudders. The windward hull is 8m/27' long, has 1.9m/6'4" headroom and a comfortable, sheltered cockpit for 4. Building time for the hulls and beams was 449 hours (at least 100 of which were thinking time, changes and work on the trailer and rig), materials cost (ex rig and rudders from harry) was $Aus4,559. I do not have a web site, so anyone wanting further information, cost and time details or photos should email me, off list. The next progress report will be in a week or so, when the launch photos are developed and scanned. Apologies for cross postings. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Rudders & Tri's From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Wed, 19 Dec 2001 10:54:33 +0800 To: multihulls_at_steamradio.com > G'day, Tim > I'd suggest the reason tri's will continue to dominate in tbe open 60 > circuit now that the platforms have evolved "square" (length to Beam) is the > huge mainsheet and forestay loads the carry. Holding up these high roached > mainsails takes tonnes of mainsheet load. > In theory a Balstron, or aerorig, type rig may do a similar function, > but I'd pick that once it was strong and stiff enough to handle the > mainsheet load it may well be a similar weight to a main hull anyway. Probably true, for rigs of this size, except that the balestron does not need cutouts for hatches, beefing up for beam attachments, or skins capable of keeping the ocean out. The ballestron is self vanging and balanced so it removes the need for a traveller, deck tracks for the jib sheets, most of the sheet winching capacity and all the beefing up required to support these items. The ballestron is a boom which extends in front of the mast and has the jib tack attached to it. The jib sheets to a track on the boom in front of the mast. In my not so humble opinion, the tri platform has pretty much reached the end of it's development. This is certainly the case structurally, as 5 tonnes seems to be as light as they get (latest ones are apparently getting heavier, despite higher strength and stiffness carbon being used). As they are power constrained (30m/100' mast head height off the water, 18m/60' max length of sail base), all they can do is reduce drag. This can be done by using hydrofoils, or much more easily, by leaving one and a half hulls and one beam on the shore, resulting in a proa platform. Imagine a tri, sailing. Take the rig and place it in the middle of the lee hull. Use a ballestron boom to take the loads. Make the lee hull double ended and place rudders near each end. Then remove the old central hull, and chop down the windward hull until it is just big enough to sit/sleep/live in and to hold as much water ballast as you will need for a given righting moment. Join the two hulls with a single beam, which won't see anywhere near the loads that either of the tri beams see. The proa will be lighter (at least until fully powered up), easier driven (far less windage, less water drag) less stressed (all the loads from one side, always) and hence faster than the tri. Where it slows down is when you need to tack. Proas shunt by reversing the rig and the rudders, and sailing off in the other direction. The rig and rudders hull is always to leeward, the crew hull is always to windward. Shunting is not much slower than tacking, but does not gain the "free" distance directly up wind which is achieved by the tri. The proa also has to stop and start again during each tack, and worse, each gybe. In a one tack beat and a one gybe run, these are not huge losses and may be offset by the performance gains. On the ocean, they are even less of a problem. My bet is that the foils will be developed first, because they can be added on to the existing platform. However, once their limitations are realised (low speed drag, added weight, propensity to crash dramatically when hitting plastic bags etc) then the inevitable next step is a weight to windward Pacific proa. I look forward to hearing why this ain't so...:-) Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Tri's & Proas From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Thu, 20 Dec 2001 16:24:05 +0800 To: multihulls_at_steamradio.com > G'day > > Tim said > So why shunt a proa as described? Why > not tack the boat normally, changing the boat from a Pacific to Atlantic > proa in an instant. I'm sure the load change could be managed with carbon > beams, and this would then mean the hull shape and foils would not have to > be compromised to change direction. I guess I'm missing something here. > Being able to manoeuvre is important to a racing winning design, whether it > be an open 60 or club racer. One of the trade offs is whether to have the mast stayed to the end of the beam(s) or to have both freestanding. The former is lighter and less stressful, which is why I like it. The shunting proa also gains a large weight/drag benefit by having a very small windward hull, and a large benefit by not having to swap the water ballast from side to side each tack. An alternative is a W type boat (cat with unstayed rig and rudder in the hull), which would also be worth a look. It should be noted that racing proas are not that much more advanced, relatively speaking, than Piver's trimarans were 40 years ago. The scope for progress and innovation is enormous. The foils rotate through 360 degrees, (2 big rudders, no centreboard) so make no compromises. In fact, steerable foils may be an advantage, if we we are skilled enough to use them. A long skinny double ended hull may or may not be enough of a compromise to justify the saved weight. I suspect it is more than offset by the advantages of a hull which is almost always supporting the entire weight of the boat, unlike tri hulls which see very variable immersion. Proas maneuvre much better than cats and tris, but differently! They don't need to be moving to maintain control, so changing tacks (especially with 2 rudders) is far more positive, and less prone to misfortune. A ballestron rigged proa at the start line will make mincemeat of conventional boats, in terms of being able to sit in the same place, making little leeway and no (or negative!) headway, then rapidly accelerating. It is also handy to be able to stop, or reverse when approaching the top mark on port. Picking up crew overboard is ridiculously simple. Dump sheet, reverse rudders and sail straight back to them. Then stop, entirely under control and hoist them aboard. > > I'd say partly the success of the Open 60 tri's is their ability to be > pushed very hard in rough weather; their width and stability make them > forgiving to the punishing sailing they undertake. They are neither wide nor stable for their sail area. They fly a hull and presumably have to depower in way less than 15 knots of breeze, judging by the flat water photos we see, I'd attribute their toughness to the experience of their designers, builders and crews in the hot-house of severe competition and unlimited budgets. Do this to a proa (or any other type of boat), the result will be the same. > > Much as I admire the elegant simplicity of the ballestron rig, its own > weight would not be less than the structure and winches that are needed on a > conventional set up. Far less, actually. On a 60' tri, you eliminate the winches, traveller, deck tracks, beam to support the traveller, main boom and all the beefing up and fastenings these require. The ballestron does not have to be solid, either. I am playing with skeletal designs using wire and compression members, anchored part way up the mast. Far lighter, bit draggier. > It also misses the point of going fast; if you are > going fast tight reaching the sails will be sheeted at tight angles, on > deck, anyway. Once sailing deep (in moderate conditions), most boats will > require more sail area, a screacher or gennaker, and these won't be set up > of the ballestron anyway. If sailing with the ballestron well eased, it is > probably time for more sail area. Obviously this doesn't apply to cruising > boats, where it is probably a nice solution. However I'd say, why have a > boom at all on a wide multihull, and save the weight and head injury risk. A screecher on a ballestron is no big deal. It just reverses the sheeting situation. That is, to luff the rig, the front end needs to be pulled in, as opposed to easing the back end. Tight reaching, the ballestron is brilliant. The jib luff is moved to windward, so the sail force is aligned more fore and aft, thus decreasing heeling, increasing speed. Trimming is far quicker as one string controls the entire rig. It is as easy to trim the rig, as to adjust the boats course as the apparent wind moves around in a gust. This means less distance is covered, should be quicker. A balanced boom is nowhere near the injury risk that a normal boom is. It moves much slower because of the jib on the front. With an unstayed rig, running by the lee is possible, as is tacking the rig instead of gybing it. This is far less dangerous than travellers whizzing back and forth across the stern and flapping headsails and their sheets. For conventional boats, I agree, the boom is heavy and dangerous. Why then, do so many boats use it? > > Speaking of which, can someone explain, who has actually used a > ballestron rig, how the mainsail is reefed without the jib backing the > mainsheet load and sending the boom back across the cockpit? I would imagine > without leech tension on the mainsheet, as when reefing, they could be a > dangerous proposition. I've used half a dozen of them. Both sails are reefed at the same time, maintaining the balance. A nuisance, but not much of one, as the whole rig lies quietly, head to wind (regardless of the boat's angle to the wind) while this is done. Alternately, reef the jib, and apply a tackle to the main sheet, or reef the main, and put a brace on the jib end. I never said the rig was perfect, just far better than what is conventionally used! Suggest you ask Gray to take you for a sail on W and show you how it works. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Tri's & Proas From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Fri, 21 Dec 2001 10:18:56 +0800 To: multihulls_at_steamradio.com Dan wrote: > larger boats have a bit of inertia that can get transferred into > distance up the course. So on every tack you're loosing about 1-3 boat lengths.snip Not working this flow could add a mile on a 10 mile leg > between 1 tri working the flow and the other going straight legs. Rob:As Dave pointed out, the losses are not this high. However, they do exist, and one of my summer projects is to quantify (and minimise) them. The question is, does a boat which is up to 50% lighter, with lower air and water drag from fewer components have the potential to be more than 10% faster? > Dan > When I see a speed advantage on a race course I'll change what I do but for now the tri is faster. I tend to think there's a reason the guys in Malibu ruled out proa's and it's not because of any preconceived ideas. Rob:I don't know about the Malibus. However, I've just built a 10.5m/35' proa, with accommodation for 3 including full headroom, in 400 hours, at a materials cost considerably under $Aus20,000/$US10,000, and weighing 550 kgs/1,210 lbs. This figure includes pro built carbon mast and rudder stocks. This particular proa's speed potential is yet to be proven, but at this weight, length and sail area, you have to admit it exists. FWIW I have plans and pro built costings for a 12m/40' proa weighing 300 kgs/660 lbs in sailing trim (620 kgs/1,364 lbs with 2 crew and Van Isles safety gear), sail area of 51 sq m/550 sq' which could be landed, ready to sail in Los Angeles for $Aus35,000/$US18,000. Lead time from paying to sailing is 10 weeks. Anyone wishing to spend Xmas perusing the numbers for either of these boats should contact me off list. It seems we have learnt little from multihull history. The early cats and tris were slow compared to monos, yet they had other advantages, and huge speed potential. Proas are in a similar situation compared to modern cats/tris. They are much more comfortable and easier to sail and have the potential to be half the weight and cost, and thus be faster. It will be interesting to see how long they take to become mainstream, and whether cat and tri owners will be as vigourous in their opposition as mono owners were/are to multis. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Tri's & Proas From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Fri, 21 Dec 2001 20:28:22 +0800 To: multihulls_at_steamradio.com > Hi all, >> > > I don't really have an axe to grind one way or the other, however, like many I find the proa and intriguing vessel. > > But I do wonder what happens in a proa if you get caught with the wind on the wrong side, especially in waves? > > Tom Follett had a huge sponson fitted on "Cheers" after he was flipped, do all modern proas do this or has the concept been superseded? > > By the way Rob, now that you've built your own proa, will you be taking after Dick Newick? He had a sign over the entrance to his office which read... "Beware...proa constructor" > > Cheers all > > Donald > G'day, With the wind on the wrong side, the ballestron rig weathercocks automatically, even if the sheet is cleated, and you can steer back onto course, quite easily. This is as likely, but less traumatic than being caught aback with main and headsail cleated on a conventional boat where the cleated jib tends to blow the boat round to a downwind course and maybe a gybe. I've never been caught aback in really big waves, but expect the technique to be the same. Cheers was (still is, it's being refurbished by some French enthusiasts) an Atlantic proa (rig and accommodation to windward) and capsized when caught aback with full sail cleated, while Tom Follett was asleep. After recovery, Newick and Follett tried to sail the boat over with the rig to leeward (ie as a Pacific proa) with full sail in 20 knots but couldn't. They fitted the sponson which operated by providing a pivot point around which the capsized boat could easily be righted. It did not prevent capsize aback, and with a weight of 65 kgs, probably helped it. (pp 150-1 "Project Cheers", a fascinating book). Later Atlantic proas all had pods of various sizes and heights, but as far as I know they were never tested although, as some of them capsized, maybe they were! These were all to windward in normal use to prevent capsizing aback. None had ballestron rigs. Pacific proas (rig and accommodation in the leeward hull), lacking in righting moment, took the concept further, with Kurt Hughes probably being the most extreme. He put an enormous pod to leeward on his 26' Pacific proa. Whether this stopped it capsizing, I don't know. It certainly looked like huge drag at anything more than a couple of degrees of heel. Russ Brown (Jim's son) uses them on his Pacific proas and swears by them, both as a warning that he is pushing too hard and for the extra space. I have not heard of him sailing them past relatively small angles of heel. He has done a lot more proa miles than me, or anyone else, so his views should be respected. I think they are a waste. The weight is in the worst possible place, as is the extra surface area. Once the boat reaches a certain angle of heel, they are prone to digging in, much like a less than 100% trimaran float, and if the boat does capsize over the pod, righting it is very difficult. Harry type pacific proas take the weight and space of the pod from the outside of the leeward hull and place it on the inboard side of the windward hull. This means the accommodation is sheltered, the rm increased and the lee hull can be kept as small as necessary to support the rig and rudders. This is the main reason for their very light weight. When the boat heels, the rudders act less and less to prevent leeway and at some angle of heel (say 40 degrees) it is sliding sideways on it's flat, unencumbered topsides, and _maybe_ not capsizing. If it does capsize (unlikely with positive rm at 70+ degrees) then it is pretty easy to right as it has a buoyant mast and boom to stop it going past 90 degrees. More stuff to test this summer.... The benefits, shape and location of pods is always good for an argument amongst proa people. For more (lots more!) information on the pros and cons, have a look at the Yahoo proa mailing list archives. Love the sign. Mr Newick is not only a gifted designer, but a wordsmith as well. I will get one for the workshop. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Latest Speed Machine From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Wed, 9 Jan 2002 20:32:40 +0800 To: multihulls_at_steamradio.com > G'day, Not sleeping, just a bit busy organising the signwriting and paint job on Harrigami, putting together a web page and sorting out a program with the sponsor. And discovering that there are better, (or at least cheaper, lighter, easier and better looking), ways to finish a boat than bogging, torture boarding and high gloss 2 pack paint. As for Mr Larsen and his boat, who knows? Hopefully he will have the confidence to build it and try it himself when/if his sponsorship quest falls through. 250k sterling seems a bit rich, materials and rig would come to less than a tenth of this, I think. BTW, does anyone know what became of the bits and pieces of Team Phillips which washed ashore? Also, are the moulds for the hulls, beams and masts still around? Regards, Rob > > > http://www.madforsailing.com/SAIL/Articles.nsf/LookUp/031D0B5895C5F50A80256B3A0050ADD9?OpenDocument > > Just don't mention the "P" word or you'll wake up Rob :-) > > Courtesy of madforsailing.com > > Gary > > > --- > Outgoing mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.313 / Virus Database: 174 - Release Date: 02/01/2002 > > --- StripMime Report -- processed MIME parts --- > multipart/mixed > text/plain (text body -- kept) > text/plain (text body -- kept) > --- > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] affordable Multihull From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Thu, 10 Jan 2002 21:06:37 +0800 To: multihulls_at_steamradio.com > > > The short question is: Is there an affordable family multi that an average guy can afford? G'day, The short answer is that there are a bunch of them, as I am sure the list members will let you know. It may be too large for what you want, but I have just launched Harrigami, a 35' proa which I built in 449 hours, at a materials cost of $AUS4,559/$US2,400, ex rig and rudders, which I already had. Sailing weight is 550 kgs/1210 lbs. Harrigami folds and is street legal on a modified box trailer. Once the launching bugs are out, it should be launched and retrieved in an hour, singlehanded. It has full standing headroom, double bunk, comfortable cockpit and enormous galley. My non sailor wife loves it. I could send you the plans, all the materials to get it to sailing stage plus a carbon mast and dacron sails for $AUS20,000/$US10,500, plus a couple of grand for freight. If you want more information, details of costs and time, or to be put on the mailing list, please let me know off list. Harrigami is currently being painted in it's sponsors colours, should be sailing again next week. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Goss Bits From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sat, 12 Jan 2002 07:14:50 +0800 To: multihulls_at_steamradio.com > G'day, Thanks for the TP info. Pity. Looks like we will have to build from scratch..;-). The magic (I wish) finishing technique is only for above the waterline, can't beat bog and hard work below the water. Pictures will be available soon, but I am informed by the painters that a substantial amount of beer was involved. As for your dinghy, I doubt you would need much, if any, bog. Maybe a light smear to fair the glass tape edge, presuming it is stitch and glue, but a better fix is to scrape the edges with a (very) sharp scraper. Then do as Martin advises and paint it. How light is ultralight? We used to build 2.4m stitch and glue dinghies with 2 seats, centreboard case and bow buoyancy at 13 kgs. Tough as old boots as well. Paint the inside with non slip. The stuff they use on concrete sticks well, is cheap, lasts forever, good uv resistance and hides overlaps etc, no trouble. Choose a muddy colour and you will spend less time cleaning it, and not have to wear shades to look at it in the sun. For the outside, housepaint is cheaper and healthier than Awlgrip. Lasts a long time, but won't wear as well. Cleans up with water and is non glossy so hides the imperfections. Neither will stay smooth after being beached or banged into wharves etc. A crappy looking dinghy is less likely to be stolen or borrowed than an immaculate one. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Biplane Rigs From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Tue, 15 Jan 2002 09:01:52 +0800 To: multihulls_at_steamradio.com > G'day, We are putting an unstayed biplane rig (wishbones, no jibs) on a 12m charter cat in the near future. Hull mould is nearly finished, should be sailing later this year. I will let you know how it goes. All that I have read about them implies there are no major problems. However, all up weight and cost is higher than a single stick. Low coe is good news in a blow, bad news in a drifter. Blanketing on a reach is not a drama if the seperation is greater than the sail chord. Only successful racing one I know of was Jaz, sailed by the Peyron brothers. It finished well up in the first Ruote de Rhum, but was later converted to a single rig. Don't know why. Regards, Rob > Does anyone know of any links to anything to do with biplane rigs on cruising catamarans? I'm interested in theory, practice, opinions, experience, pros, cons, etc. > > Thanks, > Mark Stephens > stephens_at_key.net.au > > --- StripMime Report -- processed MIME parts --- > multipart/alternative > text/plain (text body -- kept) > text/html > --- > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] proas and brass monkeys From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Tue, 15 Jan 2002 13:55:47 +0800 To: multihulls_at_steamradio.com > G'day, Joe's question was about wakes, not handling, but I will answer your questions on how proas can be easier to handle. Your last comment is correct, that "proas aren't like they were". Proas are evolving. Unlike a lot of conventional boats, this process is towards lighter, faster, roomier, cheaper and more easily built boats, rather than being driven by rig, sail and fittings manufacturers toexpensive, non working, non workable copies of race boats or condominiums. As you say, the ballestron takes all the work out of handling the rig, the same as (actually better than) it does on a conventional boat. The trick is to treat the rudders the same way. If they can rotate through 360 degrees, and are large enough not to need daggerboards, then shunting is a doddle. The steps are: Release the lightly (no purchase or winch required) loaded main sheet and the rig swings head to wind slowing the boat down. As you start to trim on the new lightly loaded mainsheet, the boat starts to move in the new direction and the water causes the rudders to automatically rotate through 180 degrees. Continue sheeting on and sail away. I can assure you, it is very easy, and low stress. I could shunt Harry (12m/40' proa), singlehanded in 8 seconds, without having to move. No winching, no flogging sheets, no changing sides. Unless they are paying attention, the passengers don't know it has happened. You are also right about shunting downwind, but don't recognise that Harry proas transcend many of the conventional sailing techniques. On a boat with no shrouds, it is no problem to run by the lee. Alternatively, you could gybe. There is no reason why a Harry proa cannot sail with the "wrong" hull to windward, particularly downwind. To help you understand why proas are easier to handle, try the following 1) Get one of your crew to jump overboard, and time how long it takes to pick him/her up. On Harry, it was 8 seconds to shunt, then sail the other way for maybe 5 seconds and stop, completely under control while he/she gets back on board. 2) Imagine you are sailing singlehanded under storm jib and deep reefed main in a strong wind with big, breaking seas, and have to tack. On a conventional multi, you bear away to build speed, pick a spot with smaller waves and push the helm down. You then say a little prayer that the boat wil get close enough to head to wind, for the jib to back. Once the backed jib has pushed the bow through the eye of the wind, you release the sheet and winch in the new sheet, all the time hoping that you are not reversed down a big wave, breaking the rudders or the helmsman's arms. Now try it singlehanded at 3 am in the pouring rain. Gybing is even worse, as it has the threat of surfing down a wave and burying at the bottom, or broaching, or losing fingers in the mainsheet traveller. On a Harry proa, you sail onto a reach, dump the sheet, reverse the rudders and head off in the other direction, for both a tack and a gybe. 3) Run aground. On a Harry proa you swear, release the sheet, pull in the new one a little, and slowly sail off. Must admit, I have never been in big seas in a proa, but can think of no reason why it would not happen like this. Been aground heaps of times and can verify that the swearing makes no difference, but the reversing off is easy. Should also point out that easily handled proas are in their infancy (Harry and it's folding succesor, Harrigami are the only 2 I know of). As more people try them, they will develop even better handling systems. Re the speed of the short hull. You may be correct, but: 1) Because the boats are lightly loaded, they can be built very light. Harrigami is 10.5m /35' long and weighs 550 kgs/1,210lbs, sailing. This helps overcome any "short, slow hull" problems. There were no indications of excessive windward hull drag on Harry, at any speed. 2) In a reasonable breeze, the short, windward hull is partially unweighted, giving it a high l/b ratio. On a racing proa, the windward hull would always be airborne, a far easier feat than flying a cat or tri hull for any length of time. 3) High prismatics on a long, narrow hull which doesn't have to tack are not a problem. Harrigami's main hull is .78, and could be higher. A stepped hull that needs to go in both directions would probably not be optimum!! Joe said that he doesn't want to get into an argument about proas and their abilities. Fair enough. I, on the other hand, love to! Particularly at the moment as I am waiting for signwriters to finish. Any one who has questions, comments or criticisms, I'll gladly try and answer them. Regards, Rob > I wrote before about boats being designed to suit local conditions (Thames > barges, Chinese junk rigs, Looe luggers etc). The same applied to proas. By > and large they were used for fishing from a lagoon in the trade winds. Sail > out on a reach to the fishing ground, lower sail, fish, then hoist sail > again and sail home. The Pacific islanders used catamarans for cruising. > Its nearly 25 years since I last sailed a proa. I've sailed both windward > and leeward types, only capsized one of them, which is probably a record. > I still cannot understand how they are easier to sail. I can see that an > Aerorig will help the rig self-end when tacking, but what about the boards > and rudders? On a conventional boat you just have to put the helm down to > tack and then sit back while the boat does the work. With a proa you work > hard all the time. But worse still is the fact that you can only turn one > way (so that the outrigger always stays to lee/windward). Thats OK to > windward and great when you run aground, but hopeless if you are sailing > downwind up a channel. Imagine having to luff up head to wind and do a 330 > deg course change because you can't gybe! > Or maybe proas aren't like they were... > > One things for sure though - hydrodynamics won't have changed. Outriggers on > tris and proas aren't there just to provide buoyancy they are hulls as well. > If they are shorter than the main hull they have to go very "fast"(like the > transom hung rudders). So they need very high prismatics, even a stepped > hull might be better (as on seaplanes). > > Why were they called monkeys? I think you'll find they were only used in > shore batteries and on catamarans - on a monohull the balls would roll off > in any sea. > Best wishes > Richard Woods > Woods Designs offer quality sailing catamarans for home and professional > builders > and also rowing and sailing dinghies for home boat builders > Website: > http://www.sailingcatamarans.com > > Subscribe to my free newsletter by emailing me with "subscribe" in the > subject line > RWoods_at_sailingcatamarans.com > Foss Quay, Millbrook, Torpoint, Cornwall, PL10 1EN UK > TEL and FAX +44 (0) 1752 823301 > > > --- > Outgoing mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.311 / Virus Database: 172 - Release Date: 27/12/01 > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Proas & rude people. From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Tue, 15 Jan 2002 22:01:09 +0800 To: multihulls_at_steamradio.com > G'day, A couple of points: 1) Joe's question was about wake drag, and he specifically stated that he was not interested in a silly debate. Richard's answer was to ignore Joe's question and start a silly debate based on a couple of sails 25 years ago. Joe was right, imo, to be sarcastic. In fact,under the circumstances, I think he was remarkably polite. 2) It would be interesting to know how many professional designers are on this list to give away their hard earned knowledge to their competition and customers as you suggest;, how many because they see it as a cheap forum for advertising or defending their designs; and how many who just like chatting about boats. My guess is zero, almost all and almost zero. 3) Asking for a price on advice after it is given is churlish. The answer is invariably "Don't worry about it". If you have received value from a designer, or anyone else who has shared their professional expertise with you, then don't ask how much, just send him a cheque. regards, Rob > Someone called Joseph Oster rudely wrote the following to Richard Woods: > >> I asked about "drag from wave interactions between the hulls", not your >> assessment of proas in general... thanks anyway (for nothing). > > We are very fortunate to have a number of distinguished multihull designers > on this list who are kind enough to share their experience and views. > Several have provided me with valuable information without charge (I > offered). For me they are always on starboard tack. > > Please would the manager of this list exclude anyone who is rude to these > multihull designers > > Tony. > > > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Proas & rude people. From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Wed, 16 Jan 2002 13:41:06 +0800 To: multihulls_at_steamradio.com > G'day, > <Rob Denney wrote. > <2) It would be interesting to know how many professional designers > <are on this list to give away their hard earned knowledge to their > <competition and customers as you suggest;, how many because they see > <it as a cheap forum for advertising or defending their designs; and > <how many who just like chatting about boats. My guess is zero, > <almost all and almost zero. > Kerry Thomas Altair Marine Limited Marine and Business Services Projects, Maintenance, Design, Technical writing. called my post "Wrong, rude, and uncalled for". Wrong? I presume you think "is zero, almost all and almost zero" is incorrect? Maybe, maybe not, but most of your post, and your signature, indicates you are in the "almost all" category. Nothing wrong with this, but let's be honest about it. Rude? Your skin is even thinner than Tony's. Uncalled for? Tony made some comments, I thought he was wrong and responded. How much more "calling" do you want, or are you also trying to censor the list so that only nice things are said about designers? Apart from proving that what I wrote is correct, you have misconstrued my meaning. I was not criticizing designers, nor their presence on the list. It is great to have them. My point was that we should not be putting them on a pedstal,in return for whatever free information we can suck out of them. They should be (and almost always are) prepared to take the heat if they are wrong, or their boats have problems, or for not answering list related questions, as per Richard and Joe. They should also be paid if they are asked for, and they provide, valuable information. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] proas and brass monkeys From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Thu, 17 Jan 2002 09:46:12 +0800 To: multihulls_at_steamradio.com > G'day, Richard Snipes wrote > I have no questions on proa, but may be you can help me understand > prismatics better. > > Am I led to believe that high prismatic hulls tend to track or go in strait > lines, whereas a low prismatic hull is less directionally stable. > Is this correct? Rob Your tracking comment is correct. Because a proa doesn't have to tack, it can use a high prismatic hull and enjoy the high speed benefits. However, the main benefit is because the centre of everything is midway along a boat which sails in both directions, there is a tendency to sail nose down with a big rig. This is exacerbated on boats which are length limited, such as harrigami which had to fit on a trailer. The high prismatic means there is heaps of buoyancy in the bow. The downside is that high prismatics have high wetted surface for a given load carrying capacity. This slows them in light air. Harry proas compensate for this as they are half the weight of a conventional multi. Another advantage of a high prismatic is that zero rocker can be used. This makes building a very easy hull shape, even easier. Any other questions, please ask. > > Tim Clissold wrote > > Perhaps one of the things not discussed with regard to proas is > accommodation. Whatever multihull configuration is chosen, accommodation > costs money. One of the things the modern (conventional) composite catamaran > has done is provide a great deal of comfort and berths, while competing with > the last generation racing boats around the track. The cost (pun intended) > is their cost. But for their owners they can be versatile yachts, very good > both at family cruising and coastal/harbour racing. I disagree that current cats with all the mod cons outperform yesterdays racers. The Formula 40's are now 10+ years old, but with new sails will still clean up any 40' cat with "a great deal of comfort and berths". It is primarily a weight and sail area issue. Until your 40' cruiser weighs 2,000 kgs, or has an enormous rig, it won't beat a F40. You are correct in regard to the lack of accommodation possible on Atlantic (Cheers etc) and Pacific (outrigger canoe type) proas. However, harry proas are different. The accommodation is in the hull which is always to windward, the rig and foils are in the hull which is always to leeward. The accommodation is not compromised by the mast and water foils, the beefing up required to support them, or a hull shape which can withstand the conditions seen by a hull which has to support the entire boat when hard pressed. Within pretty broad limits, it appears this hull, and the enclosed accommodation could be as big as you like. Harry (12m/40') has 2 queen size double bunks cantilevered off the inside of the hull, a galley, and space for a toilet and shower. Harrigami (10.5m/35' folding) has one qs double, huge galley and space for shower and toilet. Ample for a trailerable boat. Both have space for a table and seats, adequate storage space for their intended use, full headroom and sitting headroom over the bunks. They also have large, sheltered cockpits, Harry's seats 6, Harrigami 4. Both could have considerably larger accommodation if required, with very little increase in the weight or cost. > The success of a boat of course is in the eye of the owner and designer, > but perhaps the challenge ahead of proas is to be either significantly > faster, in a variety of conditions, amongst the racing multi's. Or provide > comfortable accommodation and be competitive with the racer/cruiser fleets. Success of a new boat is measured in the bank account, on the race track and/or on the cruising grounds. The first has been demonstrated, I hope to do the others this summer. Harry weighs 650 kgs/1430 lbs, with 36 sqm/387 sq' of sail,Bruce #1.75. Harrigami 550kgs/1,210 lbs and 31 sqm/333 sq', Bruce # 1.71 In theory, this would make them more competitive with any cat or tri with similar accommodation or cost. > Just being cheaper to build, by being lighter, lower energy boats, by > offering fewer berths/comforts etc would be possible in a conventional > catamaran too. I get the impression you are not convinced that harry proas are fast. light and roomy..:-) Either of these boats could be built to sailing stage for about $Aus20,000/$US11,000 worth of materials. This includes professionally built carbon mast, sails, timber, glass, epoxy, deck gear and my exorbitant design fee. If you can design a similar cost cat, with equal accommodation, ease of handling and performance numbers, I am sure the list would like to hear about it. It should be noted that as far as the wind and water are concerned, if you took a cat and put a ballestron rig in one hull, rudders at 25% and 75% of the length of that hull and made both hulls double ended, you would have a Harry proa. Therefore, things you can do to a cat, from light, spartan and overcanvassed all the way through to condomaran, you can do on a Harry proa. You would gain all the advantages of a boat that always has the same side to windward and a rig which is always loaded from the same side so it would be cheaper, lighter and safer than the original. These gains are increased if you optimise the hulls for their specific purpose. Crudely, the windward hull for living in, the leeward one for sailing. > As you've said, proas are an evolving class, which is perhaps > "competing" with more evolved catamaran and trimaran designs. I look forward > to more interesting friendly discussion and evolution. Introducing something new against an established benchmark is pretty hard work. Glad I don't need to make a living from it! You seem genuinely interested, albeit justifiably sceptical, so your comments and questions are much appreciated, I look forward to seeing your first harry proa design! I apologise to those who think that calling these boats harry proas is arrogant. I guess it is, but there was a storm of protest from proa afficionados when I tried to call them Pacific or Atlantic proas. This was reasonable as harry proas are significantly different to both. Any better names, please let me know. > Regards, Rob > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Re:biplanes From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Thu, 17 Jan 2002 11:09:32 +0800 To: multihulls_at_steamradio.com > G'day, > Mark wrote > Thanks for the reply. The charter cat sounds interesting, please do keep me > informed. I'm just down Coffs Harbour way so would be interested in checking > her out when she's ready. I like your proa ideas too, be great to see one. > You may remember me, I left my newly built F25A in your shed many years ago. Wondered if it was you. I am now in Perth, so it is a bit more of a hike to see the boats. You are still welcome to come and have a look. > As your signwriter is working maybe you would have time to explain your > comment 'Blanketing on a > reach is not a drama if the separation is greater than the sail chord'. > Wouldn't there be a point of sail where one rig effects the other? Apparently not, if they are one sail chord apart. Not sure how precise this is, but i have seen it mentioned a few times. Maybe Tom or one of the aerodynamics whizzes can give you the reasoning. Even if they are, it is small beer to change course by 10 degrees to put the leeward one in clear air. > I am > hoping that the higher costs involved with two rigs can be offset by being > home built and the need for far less commercial mast and deck hardware. May well be. What are you going to build the masts from? Carbon tubes go for about $Aus300 per kg. > The > weight may be offset by lighter mast bulkhead structure. Not vs one mast in one hull, but maybe vs one in the middle. Won't be much, i wouldn't worry about it. > The light wind > disadvantage would be a problem though setting a couple of big drifters may > help. They could be full boat length along the foot, so area is not a problem. Height will be, but if it is that light, either do some fishing, start sculling, or charge the batteries. > How about two tall Nigel Irens' modern lug rigs effectively creating > telescoping masts. I am talking cruising of coarse. Lug rigs have a lot going for them, for racing and cruising. It is almost certainly what I will use for Harrigami's new rig, although that has the benefit of being able to trim the lug from the windward hull on all points of sail. Please tell me more about what MarineCad does. Offlist. > Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Re:biplanes From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Thu, 17 Jan 2002 22:03:51 +0800 To: multihulls_at_steamradio.com > G'day, Thanks Tom. Much appreciated. I was referring to the distance apart to prevent them interfering with each other, didn't give a thought to the best planform. I was assuming same total area, same proportions. Like you I have never seen two equal span rigs drawn as an alternative to a single rig of the same area. Presumably this is because keeping the same mast height and shortening the boom virtually doubles the cost and weight compared to reducing both the mast and boom, assuming that both masts are robust enough to capsize the boat. I will discuss your post with the biplane designer. He has his heart set on 2 blown up windsurfer rigs, but this may change his mind. regards, Rob > On Wednesday 16 January 2002 19:09, you wrote: > ... >> Apparently not, if they are one sail chord apart. Not sure how >> precise this is, but i have seen it mentioned a few times. ... > > It's not the chord that matters, it's the span (foot to head). You can find > the relationships at > http://www.desktopaero.com/appliedaero/configuration/multiplesurfaces.html. > > If the two rigs are the same size (leaving out proa biplanes!:-), the induced > drag is given by the relationship: > > Di = (Lp2 + 2*Lp*Ls*sigma + Ls2) / (1/2*rho*Va2*pi*b2) > > Di is the induced drag > Lp is the lift produced by the port rig > Ls is the lift produced by the starboard rig > sigma is the interference factor > rho is the air density > Va is the apparent wind speed > b is the span > > The interference factor, sigma, goes between zero, when the rigs are very far > apart, and 1, when the rigs are together - the single masted case. Now > L2/(1/2*rho*Va2*pi*b2) is the induced drag of one of the rigs in > isolation, so the interference always increases the drag. For typical > catamarans, I'd expect the separation to be around one-third to one-half the > mast length, so sigma is going to be in the neighborhood of 0.4 to 0.3 and > the induced drag will be 15% to 20% higher than if the rigs were not > interfering with each other. > > At first blush, it looks like the biplane rig is much more efficient than a > single masted rig - and it is, provided that the two are compared on the > basis of EQUAL SPAN. That would require that the biplane rig have the same > luff length and half the foot of the single masted rig, which would make for > a pretty high aspect ratio (skinny) sail. But I've never seen a biplane rig > drawn that way. > > Instead, the biplane rig designs I've seen have the rigs proportioned the > same. So the span of the biplane rig will be 70% of the span of the single > masted rig. Since the induced drag is related to the span squared, the > similarly-proportioned biplane rig will have the same drag at infinite > separation as the single masted rig. With typical gaps, the interference > will add that 15% - 20% increase in induced drag again when compared to the > (taller) single-masted rig. > Say the induced drag is around half the total drag, that would make the > aerodynamic L/D of the of the biplane rigged boat around 90% of the > conventional boat, with a corresponding hit to windward performance. If the > height of the biplane rig were increased to 80% of the single mast rig, it > would erase this penalty. Even with the penalty, the sail-handling benefits > might make it well worthwhile for a cruiser. > > Cheers, > > -- > Tom Speer > F-24 Ama Deus > http://www.tspeer.com > me_at_tspeer.com > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Lugs/gunters From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Fri, 18 Jan 2002 17:04:18 +0800 To: multihulls_at_steamradio.com > > >> >How about two tall Nigel Irens' modern lug rigs effectively creating >> >telescoping masts. I am talking cruising of coarse. >> >> >> Lug rigs have a lot going for them, for racing and cruising. It is >> almost certainly what I will use for Harrigami's new rig, although >> that has the benefit of being able to trim the lug from the windward >> hull on all points of sail. >> >> >> >Regards, >> >> >> Rob > > Rob, > > Would that be a battenless standing lugsail? Advantages over balestron? > > Gary G'day, Sorry, memory problems. Just checked a picture of Roxanne. Not what I had in mind at all. The lug sail on Roxanne is balanced, so should be pretty low on sheeting loads. Suspect it is a bugger when you point too high, maybe collapsing like a spinnaker, and taking a big bear away or over sheeting to get it full again. Not sure whether the yard is tacked, or how, but presume there is a system. Also not sure how big you could go before stretch problems became a nuisance. Otherwise it looks pretty good, certainly very light. Think I would prefer full length battens (a junk rig?) for long voyages. I was thinking of a fully battened gunter rig, such as on Mirror dinghies. The top mast slides up and down with the sail as it does on the lug, but it and the mast would be in sleeves in the sail. Would still use the ballestron for it's ease of handling, reaching performance, versatility and lack of beefing up required on the boat for shrouds, stays, winches and tracks. Advantages: Easier rigging as only 2/3 of the mast to get upright on the trailer. No track on the mast saves weight and work, sleeves are more efficient. Probably put a parabolic leading edge on the mast pieces. Able to attach the jib stay and still have sleeved sails Be fun to play with something different. Conventional mast/sail arrangements are far from ideal. Less drag when reefed. This will probably tempt me into a bigger rig, partially negating the easy erection. Easier to build, particularly the bottom untapered section. Would try strip planking with pultruded carbon strips. Temptation will be large to have a go at building a one piece pre bent top section. Less drag at anchor and motoring Disadvantages A little more weight, slightly offset by the lower halyard position and no track The discontinuity will be a challenge for the sailmaker, but the Mirrors seem to handle it. Some means of adjusting the sleeve size (velcro/lashing) is probably necessary Lowering the top part of the sail with the battens in. Batten/mast connection would need to be flexible, probably a C shaped fitting on the mast end, and feed them in from the luff. Any thoughts, comments or criticisms much appreciated. None of this will be happenning till the current mast breaks. Regards, Rob > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] proas and brass monkeys From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sat, 19 Jan 2002 16:43:21 +0800 To: multihulls_at_steamradio.com > Paul wrote > Even calling them Rob Denney proas wouldn't be arrogant after the flak you copped for calling them Pacific Proas. > Harry proas seems a good starting point however since you are now adjacent to the Indian Ocean rather than Atlantic or Pacific perhaps they should be Indian proas? > Paul Nudd G'day, Good idea, but might get confused with indigenous Americans' canoes and whatever people sail on the subcontinent! Dave wrote > As this type of proa was first suggested, and extensively written about, by Joe Norwood (21st Century Sailing Multihulls, AYRS, 1996), shouldn't they properly be called Norwood proas? > > Sure, Rob beat Joe to the building (and, in fairness, never read Norwood until Harry was nearly finished), but there's a long and distinguished history in chemistry, physics and engineering, for naming a novel idea after the first to accurately propose it. > > Calling Harry a "harry proa" isn't arrogant, it's simply erroneous. Rob As Joe pointed out, this is probably better discussed, yet again, on the proa list. Suffice to say, that the Norwood proa had a daggerboard and hydrofoils, as well as the weight to windward. Harry proas are more than just the weight to windward; they are the sum of the ballestron rig, the oversize 360 degree rudders, the lightly loaded structure enabling them to be built light plus the weight to windward to provide rm. I had twin rudders and ballestrons on proas before 1996 and somewhere, there is a pre '96 Queensland Wooden Boat Society newsletter with a picture! On the subject of precedence in science etc, you may be right. In boats, it is always the type or the name of the first one. eg Atlantic proas, not Newick proas. I can't recall any types of boats named after their designers. On a lighter note, Norwood simply doesn't have the name potential of Harry. eg Harrigami the folding harry proa (Harry + origami) Harriverderci the Italian harry proa Harrison Fjord the Norwegian harry proa Dirty Harry for the no nonsense, harry proa Harrikiri for the ultra light over rigged harry proa and for The Race, Extraordinarry a 120' harry proa weighing less than half Team Phillips' weight. This one is currently being drawn for a New Zealander. etc etc,further contributions appreciated Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Re: Lugs/gunters From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sat, 19 Jan 2002 17:20:24 +0800 To: multihulls_at_steamradio.com > G'day, David > Rob presents an interesting rig idea, and I'd offer one more disadvantage > snip. Track might do it, but you seemed to want to avoid that. I was planning on using a collar, and also a light, adjustable masthead shroud. Perhaps the yard should be called a "gunt"? :-) > > I'll bet you'll use carbon for the yard, snip. Absolutely carbon, maybe strip planked using putruded strips. These are becoming very cheap, sufficiently so that I hear they are being used to reinforce the biggest bridge in Melbourne. Not quite Golden Gate size, but bigger than London. The collar should stop the gunt waving round too much. Problem with a gaff is that it is difficult to control the twist between gaff and boom. Maybe full length battens with sheeting??? > > > P.S. Most luggers like Roxanne doesn't normally tack the yard, they just > live with it on shorter legs; on long legs they lower it and re-raise it > on the proper side. I would have to tack it every time. The sight of it would drive me nuts! Gary A couple thoughts: snip Maybe a one piece sail with a gaff in a pocket, stiff enough to sheet to but flexible enough to bend? The crease is the big worry. Need a sailmaker who will keep playing till it's right. rare breed. Also thought about camber spars in wide pockets for the gaff batten. Couldn't handle tacking the topsail, and certainly couldn't handle not tacking it! Sheeting of the spars, (and maybe the battens) to windward is a definite. But, like you say, it would be fun to play with something different. D > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Spitfire 12 From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sun, 3 Feb 2002 20:35:28 +0800 To: multihulls_at_steamradio.com > At 11:19 AM 2/3/02 +0800, you wrote: >> Hi folks thought I would let you know that I've saw something that make >> the heart beat faster today ..... "Spitfire 12" it a Perth(Australia) >> Design 12.2 metre Cat with hydrofoils 2 carbon fibre mast. They've only >> just launched the the cat , but achieved 25 knots in 14 knot wind and >> are confident on obtaining 35 knots. They have a web site that may give >> you more info. http://www.bydesign.com.au >> I have no involvement in the company ..just out sailing and saw her. > > Looks as though Robert Hobbs twin skin sail designs, which we found a bit hard to swallow, performance wise, a couple of years ago on this list did have the kind of merits he was claiming, I understand he is part of the design team.. I suppose curry is a good condiment for crow? > > Roy Mills > G'day, I don't think here is nothing inherently wrong with the Dynawing concept, in fact it has been taken over by soemone else and they are putting a ballestron version of them on boats for handicapped sailors. Hopefully they will get a racing one done sooner or later. However, the Spitfire doesn't use Dynawings. It has a split sail on tow tracks on the mast joining part way back to a single skin. The boat is awesome, and the guys who designed and built it, very clever cookies. They are now debugging it and getting it ready for Brisbane Gladstone and AMOC. The original plan was to use Dynawings, and they were used successfully on a monhull prototype some years back, but for reasons I don't know, they changed to the split sail. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Annapolis to Bermuda Race From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Thu, 7 Feb 2002 23:11:07 +0800 To: multihulls_at_steamradio.com > > > It's too bad that on a knots/dollar scale, multis don't do so well. Ever think this will change? > > Larry Forgy G'day, It has. We did 14 knots on Harrigami (10.5m/35' traillerable proa weighing 550 kgs/1,210 lbs) yesterday, in about 14 knots of breeze. All the materials for building it to sailing stage are available for $Aus20,000/$US10,000. Does this make it $US714/knot? How does this compare with your Clorox botle, or the F27? Good luck with the crew position. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Annapolis to Bermuda Race From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Fri, 8 Feb 2002 20:49:41 +0800 To: multihulls_at_steamradio.com > At 11:11 PM 2/7/02 +0800, you wrote: > >> G'day, >> It has. We did 14 knots on Harrigami (10.5m/35' traillerable proa weighing 550 kgs/1,210 lbs) yesterday, in about 14 knots of breeze. > > Hi Rob, What was the apparent wind angle when you did this - approx. > > Roy Mills > G'day, Too busy grinning and listening for cracking noises to really notice, but I do remeber thinking we were quite hard on the breeze, so I'd say apparent of 45 degrees, give or take a bit. It is a weird feeling, sailing such a light boat. The chop doesn't seem to affect it at all, but as soon as the rig luffs a little, it slows down dramatically. Sheet on or bear away and it takes off with a rush. Both of us lost our balance at various times. Should be interesting in serious wind and waves. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Re: Knots/dollar From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sun, 10 Feb 2002 20:44:37 +0800 To: multihulls_at_steamradio.com > John Shuttleworth wrote: > > The final total weight of the slim hulled 40 ft racing tri would be 2000 > Kgs in racing trim including 3 crew. > > The approximate overall cost of the 50 ft cat would be about £ 500,000 and > the 40 ft Tri about £ 250,000 > > G'day, Many thanks for the excellent analysis. Would it be possible for you to go one step further and tell us the break down of the cost and weight of the 12m tri components? ie hulls 415 kgs, 14,434 stg, beams?, rig?, foils?, safety gear for racing trim? Thanks. regards, Rob > > > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Sailplan From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Thu, 14 Feb 2002 22:48:05 +0800 To: multihulls_at_steamradio.com > G'day, Sounds like fun! Reminds me of my youth, bashing out to Barrier or up to Kawau in the Pied Piper. Any ideas of average and max wind speed, boat speed, and vmg? Regards, Rob > Tim: Having slogged > upwind in the weekend with three reefs, storm jib and big waves through Tiri > Channel (just North of the AC course) with a nicely stabilised mast I can > speak from some experience! > > _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Harrigami mailing list From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Thu, 14 Feb 2002 22:59:24 +0800 To: multihulls_at_steamradio.com, proa_file_at_yahoogroups.com G'day, The following have asked to be kept updated on harrigami, but have changed (or I have had problems with) their addresses. If you still want the updates, please let me know. <jrobertson_at_edgenet.net> (reason: 550 5.7.1 <jrobertson_at_edgenet.net>... Access denied) <lvogtman_at_fred.net> (reason: 554 <mail014.syd.optusnet.com.au[203.2.75.175]>: Client host rejected: Your IP is listed as an international Spamhouse.) <robertfynn_at_msn.com> (reason: 550 5.2.1 robertfynn_at_msn.com... Mailbox disabled, not accepting messages) <kankamacat_at_hotmail.com> (reason: 550 Requested action not taken: mailbox unavailable) <tomhenry_at_direct-connection.com> (reason: 550 5.1.1 <tomhenry_at_direct-connection.com>... User unknown) <winston1_at_erols.com> (reason: 550 Unknown local part winston1 in <winston1_at_erols.com>) <rsrddsmcs_at_home.com> Account inactive <br_at_catalog-international.com>... catalog-international.com: Name server timeout Anyone who hasn't got progress 4 (or who wants it,) please let me know. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] www.harryproa.com From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sat, 23 Feb 2002 11:04:22 +0800 To: Recipient List Suppressed:; G'day, Our new web site is now up and running. There are still a lot of things to be added to it and progress reports will be included as they happen. I will not be mailing out regular reports as I have in the past. The site name is www.harryproa.com Any comments on the site, or on what you want to see on it, much appreciated. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] knots/dollar, Cedar vs Foam From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Thu, 28 Feb 2002 11:48:52 +0800 To: multihulls_at_steamradio.com > G'day, Any chance of seeing the numbers used in the exercise? Regards, Rob > Having just gone through the exercise with two clients, saving money in > the hull construction at the risk of reduced resale value and performance > doesn't make sense: The hull cost increase from plywood to Foam Composite is > insignificant on the whole cost of a project. > > Regards > > Tim Clissold > www.tcdesign.co.nz > > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] knots/dollar, Plywood vs Foam From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Sat, 2 Mar 2002 08:50:41 +0800 To: multihulls_at_steamradio.com > G'day Tim, Ted and others Thanks for the information. Not my place to criticize the owners choice. I just wanted to see the numbers. Some points 1) Getting an engineering company which also sells materials (High Modulus, SP, FGI),to spec a boat and supply the materials has never seemed a very clever move to me. Particularly if you want analysis of materials they don't sell included. 2) It isn't hard to get rounded looking hull shapes in ply. 3) You talk of 5% of the finished cost of $200,000 being retrievable on the resale price. I'm dubious, particularly if the $10k was invested for the time the boat was owned. Any idea what the resale price of each would be? Again, just curious. 4) Finally, did you also do the numbers for cedar strip? Seems to me the yanks are paying through the nose for the stuff. Middle of last year I was quoted 40mm x 10mm (1.6" x .37") western red cedar, clear grain, smooth sawn, ready to use, in 6m/20' lengths for $Aus28.50 per sq m. This is $US1.37 per sq foot, not the 5 bucks a sq' that Ted pays. Paulonia is 15% lighter than cedar, even slower to rot, and costs about 1/2 as much. FWIW we also pay about $Aus11 per litre ($US22 per gallon) of boatbuilding epoxy. Seperate issue. Tim, any chance of posting a copy of the NZ Boating article on a web page? The mag doesn't make it this far west, unfortunately. When is this year's Coastal Classic? Slim chance that we will be there. Don't suppose you want to come over for AMOC, then cruise back in company? From other posts: In ten years in and around strip planked boats all over Australia (where there are more of them than anywhere else in the world), I have yet to hear of a cedar boat suffering from core shear, serious outgassing, osmosis or skin/core delamination (even on a couple of boats who used polyester). No shortage of foam examples. Cedar also rots (slowly), but I know of no cedar strip planked boats which have suffered this. A few balsa strip boats have had rot problems, but no cedar ones. The environmental argument is specious. It takes one hell of a lot of energy to produce foam and the extra glass and resin required (probably double for the 10mm core), than is gained by not using a tree. Cedar will, eventually, decompose. Foam won't. regards, Rob www.harryproa.com -- Associate Professor Sue Berners-Price School of Science Griffith University Nathan, Brisbane Qld 4111 Australia Phone:+ 61-7-3875-7825 Fax: + 61-7-3875-7656 e-mail: S.Berners-Price_at_sct.gu.edu.au ** New address From 12 March Professor Sue Berners-Price Professor of Biological Chemistry Department of Chemistry The University of Western Australia 35 Stirling Highway Crawley Perth WA 6009 Phone:+ 61-8 9380 3258 Fax: + 61-8 9380 1005 e-mail: S.Berners-Price_at_chem.uwa.edu.au _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Copper Epoxy From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Mon, 4 Mar 2002 18:28:26 +0800 To: multihulls_at_steamradio.com > G'day, I used to sell (and for a huge fee, apply) Copperpoxy. Found the easiest way was to roll on the first cost, and then squeegee on the second, using the stipples to ensure adequate coverage. Make sure you squeegee in both directions, to avoid shadows behind the stipples. Given boat owners interest in unpolluted water and unadulterated sea food, it never ceases to surprise me that they even think of using anything else. Which brand did you use? Regards, Rob > We had Copperbot on our Prout 34 from new. When we sold it about 5 years later it was still going strong. > > It needed a pressure wash once or twice a year to get off the brown slime that forms on most boats in Portsmouth harbour regardless of brand of antifouling. We rubbed the bottom down once with handfulls of sand whilst on a beach which seemed to revitalise things a bit. > > I put a copper epoxy on Zazen before Christmas. I can confirm that its very difficult to sand off the stippled effect left by a roller. > > The stuff we used was a water based epoxy but still sets very very hard. > > Gary > > > --- > Outgoing mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.320 / Virus Database: 179 - Release Date: 30/01/2002 > > --- StripMime Report -- processed MIME parts --- > multipart/mixed > text/plain (text body -- kept) > text/plain (text body -- kept) > --- > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] knots/dollar, Plywood vs Foam From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Mon, 4 Mar 2002 18:36:06 +0800 To: multihulls_at_steamradio.com > G'day, > I find myself agreeing with you Rob, this is no fun! try telling me that proas don't work!!! > 4) Finally, did you also do the numbers for cedar strip? > 4/ No I haven't done the exercise myself recently, but second hand reports > of cedar cost would be more expensive than the numbers you quoted. What is > the equivalent PVC foam cost in your area to complete your comparision? 20mm H80 costs $67 per sqm for 20mm, presume 10mm to be at least half this. Plus it needs at least another 200 gsm of cloth and resin inside and out, and beefing up in the way of fittings etc, which cedar/paulonia don't. > > Boat Test: I intend to put as much on my website as I can, but probably not > till the end of the month when this issue is finished. Obviously I don't > want to stand on the editors toes after she has done such a good job. Look forward to seeing it. Actually, a better idea would be to send it to Ava at Multihulls mag in the USA, and to Paul Lynch at M/hulls in Aus. Both should jump at the opportunity to print it. Let me know if you need addresses. BTW, have you done any racing in your boat yet? > > Coastal Classic: 26th of October this year. I may well sail to Aussie at > some stage, but it won't be this year. Will 'W' do it this year? I saw it at > the work berth looking ready to race the other day. No idea what is happening with W, I haven't had my annual invitation to come across and race, "once the bugs are out". I would do it in Harrigami, although I'm only half serious about sailing it over. The best way to silence the critics, but a bit cold at that time of year. AMOC last race is 11th October, so it will be a tight fit timewise. Anyone on the list got contacts with an air freight company? > > Cedar Boats: I agree, there are scary exmaples of foam boats having > problems. But often they are either racing yachts pushed hards, or boats > involved in hot Post Curing. That whole Post Curing is a black art in my > opinion; why would you heat up a foam structure that deforms when is it gets > hot? The racing boats are the ones that are "engineered" and built from the best materials by the most expensive techniques. What hope the poor mug who doesn't have a clue how to use a vacuum pump and thinks "outgassing" is a polite term for flatulence? There have been many more problems with boats built from contoured foam than with the racing boats. And many more again with osmosis, delamination and outgassing from lousy building techniques. Post curing is indeed a black art. You are not only heating up the core to very near it's softening temperature, but all the air (and water) in it expands and wants to go somewhere, and finds it can't because the skin is in the way. So, it blows big bubbles in the soft foam . Far better to cook it completely while it is under vacuum. Even better is to up the skin spec a little and use resin which doesn't need post curing. regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] News from Downunder From: Rob Denney <carbondesign_at_dingoblue.net.au> Date: Wed, 10 Apr 2002 07:47:37 +0800 To: multihulls_at_steamradio.com > G'day Well done Paul, and thanks for the report. Brought back some nice memories. Any chance of some more details (wind etc) and details of the time between Jamie, Rontidjuu and you. Who was next. Congrats also to Jamie, this is the 4th or 5th time he has taken line honours. Regards, Rob > How good is this? I get my local news via Bill Gibbs. > Still good to get the news! > I just did the Brisbane to Gladstone on Free Spirit. > Free Spirit is a 40' Crowther design 256 Supershockwave, > rather like XL2 with a bridgedeck, a carbon rotating wing mast > and a couple of feet extra length. > The event was won by Jamie Morris in his 40+' Grainger formula 40 style open > cat. > Second was Philippe Coste in Rontidjuuu (Crowther design 318, 56' carbon > podcat), _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Rudolf, the coal nosed ...was spelling Diesel From: Rob Denney <proa_at_tpg.com.au> Date: Tue, 14 May 2002 20:28:47 +0800 To: multihulls_at_steamradio.com From:Chris > Take the proa, where are they now ? (Is Rob-AUS in ?) G'day, Certainly is. Harrigami works well in breezes up to 30 knots, although there are a few things I will change (stiffer mast, demountable instead of folding, few mods to the trailer). There is an article in the next Aus and US Multihulls mags. Current project is trying a few different ideas to see how it goes with a racing crew (4 minimum, according to the rules). Less emphasis on fast easy sailing, more on speed regardless of the work involved. May even need a winch! I have built a new, minimum windward hull (6mx1.3mx0.8m, 2 rag bunks, bucket, and candle for cooking) and am about to start building a 14.7m/48' telescopic mast for a sleeved main una rig with 50% more sail area. Unstayed mast, including fittings should weigh 40 kgs/88 lbs. Carbon, resin and consumables have cost $Aus2,000/$US1,100. Fair bit of labour (unskilled) involved. After the mast I will build, new, longer, smaller section beams using a similar technique. Hope to also get time to install drum rudders. (Against Nuddies advice, but I have a couple of guys who want them, so I need to find out how/if they work.) Plan is to take it to Sydney for the Aus Multihull champs (AMOC) in October, and if it is not too scary, maybe sail it over to NZ for the Coastal Classic. Pete, Glad you are wondering, but as long as you enjoy the messing about, it doesn't really matter where the axis of symmetry lies. When are you coming over for a sail? There is still a berth available for AMOC.... regards, Rob www.harryproa.com _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Harry Proas From: Rob Denney <proa_at_tpg.com.au> Date: Mon, 20 May 2002 13:54:48 +0800 To: multihulls_at_steamradio.com > G'day, Glad you like it. A similar one is in the next Multihulls USA. Please note the web address in the article is wrong. It should be www.harryproa.com Regards, rob > Hi Rob and all, > Congratulations Rob on getting such a good article on your proas in the > Australian Multihull World Magazine. Very informative. > > Regards > > Tim Clissold > > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Safety regs From: Rob Denney <proa_at_tpg.com.au> Date: Wed, 22 May 2002 08:03:09 +0800 To: multihulls_at_steamradio.com > G'day, > > Offshore Special Regulations > > A Proa is excluded from these regulations. > -------------------------- > What is your reaction proaphiles? > Paul Nudd G'day, This proaphile is quite happy to let results speak for themselves, once I have some! See you at AMOC (Australian Multihull Offshore Champs). My entry has been confirmedprovisionally, although experience shows that if we are anything other than last, there will be a bunch of sad arse protesters who will try to throw us out. Can't wait! Ted said Proa developers, including myself, have yet to prove that a proa, either Atlantic or Pacific, can be made seaworthy enough for long passages. The problem in a nutshell is that the Pacific Proa does not generate enough specific righting moment, that is all of the weight of the boat does not contribute to righting moment as does a catamaran, trimaran and Atlantic Proa. The problem with the Atlantic Proa is that it is not stable in transition with the rig to windward. I would guess that the Atlantic Proa might be a better candidate to develop. However, there doesn't seem to be any topic which is more emotional and irrational than proas on this maillist. If someone is to defend their Pacific Proa design they should always include a calculation of its righting moment compared to a similar trimaran or catamaran, otherwise they are just blowing smoke. Rob A few points, which may explain why proa people get emotional when faced with errant nonsense. 1) Chances of proving Tiny Dancer (Ted's off the beach proa) seaworthy for long passages are pretty slim. Be good to hear how it compares with Tornados though, and to hear about his other attempts to prove proas are seaworthy. 2) Making Atlantic and Pacific proas seaworthy is no problem. Russ Brown has sailed up and down both coasts of the USA, and across to Australia in his 11.5m/38' Pacific proa, with no problems. Cheers (first Atlantic proa, 12m/40') finished 3rd in OSTAR '68. The problem is not the boat types. It is the people who sail them with insufficient ability and those who judge them with insufficient knowledge. 3) All the weight of a cat or tri does _not_ contribute to their righting moment. The formula is beam*0.5*all up weight, with adjustments for crew position, if you want to get picky. 4) Taking righting moment in isolation of other features (weight, length, sail area, even cost and space) is as illogical as taking any other parameter in isolation. 5) What is "transition with the rig to windward"? Cheers was perfectly stable in all states, enduring 55 knot gales in the North Atlantic, with ease. Granted, she was capsized when caught aback (rig to leeward) with full sail up and the crew asleep, but there are plenty of similar occurrences with cats and tris. 6) You ask for righting moments and comparisons. Sure. Harrigami(Hg) has a righting moment in racing trim of 36,000 kgm (6.5m beam, 600 kgs in the weather hull). A bit more in cruising trim, which includes double beds, full headroom, big galley, shower, sheltered comfortable cockpit. Takes about an hour to change from cruiser to racer. Perhaps you could give us some numbers comparing this to a cat or tri with similar righting moments. Some of the starting points for your boat might be: Weight: Hg in sailing trim (ie no crew or safety etc gear) weighs 550 kgs. Sail area: In racing trim, 45 sqm upwind, cruising 31 sq m. Cost: Hg materials to sailing stage ( mast,beams and rudder stocks (all carbon), sails, all rigging, plans, timber, glass, epoxy, etc) are available for $US11,000, plus a grand or so freight. Labour cost varies, but I'd happily build one for $US10,000. Length: 11m Beam 6.5m Rig height: 14.7m main luff Hull construction: strip planked timber/glass/epoxy Harrigami in cruising trim has been sailing successfully for 6 months, in breezes up to 30 knots. Racing trim (new rig and windward hull) is happening in the shed as I write. Be interesting to see what cats and tris Ted can compare these numbers with. Or is he just blowing smoke? I am sure Joe Oster or Dave Culp can tell us the numbers for Russ's boats and you can compare them as well. regards, Rob www.harryproa.com _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Safety regs From: Rob Denney <proa_at_tpg.com.au> Date: Thu, 23 May 2002 08:11:12 +0800 To: multihulls_at_steamradio.com > replies to Ted, Ross and Paul. Probably pretty boring if you aren't into fast peculiar boats. G'day, > Ted said > Rob Denney wrote: > >> 2) Making Atlantic and Pacific proas seaworthy is no problem. Russ >> Brown has sailed up and down both coasts of the USA, and across to >> Australia in his 11.5m/38' Pacific proa, with no problems. Cheers >> (first Atlantic proa, 12m/40') finished 3rd in OSTAR '68. The >> problem is not the boat types. > > Both assertions are not quite true. If you read the book about the > development and racing of Cheers and talk to Dick Newick you will > find that there was a continual issue with stability, both in being caught > aback and in pitchpoling. I know Russ and Lew MacGreggor, who > built and sails a Russ Brown proa. They are both quite up front about > the fact that they are difficult to sail offshore and not for the average sailor. > I believe that Russ strikes sail at night. Rob If you were to talk to Steve Fossett, he may "have a few issues with stability, both in caught aback (under masthead gennaker, with water ballast tanks on the windward side full, for example) and pitchpoling". He will be "very upfront about his boat not being suitable for the average sailor". This does not mean maxi cats are unsuitable for ocean crossings, any more than it means proas are. Both assertions are absolutely true. I have read the book innumerable times, and have photos of Cheers on my office wall. It was the first boat of it's kind, and the caught aback issues were well sorted by the end of it's career. The pitchpoling was a result of insufficient freeboard at the bows, nothing to do with it being an Atlantic proa. If you insist on nit picking about Cheers, then About Face is an Atlantic proa which cruised around Australia a few years ago. Without problems, occasionally singlehanded. Russ reduces sail at night in conditions which warrant it, as do I when sailing offshore, shorthanded. He is a very good, cautious seaman. Most of his problems are to do with his rig, not with the fact that it is a Pacific proa. If you want to nit pick about Russ's performance, then note that Pacific proas were making long, safe, high speed oceanic voyages when Mr Columbus was still trying to achieve positive vmg upwind. You said "have yet to prove that a proa,either Atlantic or Pacific, can be made seaworthy enough for long passages" You are wrong. Traditional proas, About Face, Cheers and Russ' boats prove beyond doubt that it can be done. When someone puts as much effort into refining the concepts as has been put into cats and tris, i think we will find that proas are the fastest of the three types. They are already the lowest cost per knot of boat speed. The rest of Ted's post had nothing to do with Safety Regs and proas so I have started 2 new threads. Ross Hobson said Rob good to see that you will be racing - but don't race to condem if you are excluded snip as the race authorities have a duty (as proved in your own courts following the hobart disaster) to rnsure the boats are suitable and safe to race. I think my message is to ensure that you are soooo safe that they cannot exclude you. That certainly was the approach we in the UK took when RORC opened thier races to multihulls. We made a big effort to comply with every facet of the sfatey rules. This can be seen by the fact that now ORC cat 3 races allow multis without escape hatches - we initally started off that escape hatches were comulsory for all offshore evebts - which exclued the F31's Rob I have nothing but respect for race officers in these litigous times. I won't be condemming anyone. If we do well, I fully expect to be protested against, (they are an interesting crowd, Australian and NZ multihullers) and will be obeying all the rules, including mandatory miles pre regatta. I stopped competing for the sake of the silverware years ago. If I abide by the rules, but am not allowed to race officially, I will get plenty of jollies racing unofficially, and enormous pleasure letting boats through when, if we were racing, I would have had right of way. Raced the Sydney Hobart fleet in a 12m tri (Verbatim) a few years ago. Beat the fastest boat's (80' maxi) time by 20 minutes. Absolutely no recognition from anyone from the boats meeting the fleet through to the local clubs, yachties and press. Didn't detract from my enjoyment at all. The safety hatch issue surprises me. I have capsized twice, the first time without a safety hatch in the nth Atlantic (years ago, in a barely finished cat, but this is no excuse) and would never go out of swimming distance of land without one. Anyone who does, needs their head read, in my unhumble opinion. I am amazed that Ian does not make them mandatory. If it is for structural reasons, this is a major failing in an otherwise fantastic (if expensive) boat. Paul Nudd Who has provisionally confirmed your entry? Rob Ken Hurling, commodore of the QMYC, which is running the event. Not sure if he is a race official, but his approval is certainly enough to justify a proper entry and turning up. I asked for a concession on crew numbers (why have a huge crew on a boat which is designed to be sailed shorthanded?) They insisted on 4 so I am enlarging and complicating the rig to give them all something to do. This is a club rule, not an AYF one. Paul Presumably AMOC is to be run under the AYF "Blue Book". snip I don't know if the AYF mirrors the proa exclusion. Rob I could not find anything in the Blue book about proas. They define monos, and state all others are multihulls. Ditto the NZ regs, but I have already been refused entry for a proa (solely because it was a proa) in the Coastal Classic in the past. Plan (dream) is to sail over after AMOC and do a Cheers, although possibly not in such a gentlemanly way as they did. ;-) Paul Another alternative might be to submit your own set of regulations relating to proas, citing yourself as the only person suitably experienced to do so. Rob Cool idea, although they would not be very different from what currently exists. My problem is not with the rules, it is with the stupid boats (in the case of the Hobart fiasco) and people who sail them. Don't get me started on this! Paul I do hope you can race and I hope you don't come last. I also hope the "bunch of sad arse protesters" don't have the opportunity to throw you out on the basis that you declared you complied with the regulations. Rob Someone has to come last, but I agree with your sentiments. Thanks. see above about obeying the rules. Paul I also hope that AMOC will actually happen, in Sydney, this year, but I have my doubts. Rob This would be a major nuisance, although it would take some of the building pressure off. Please keep me informed. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Apples and apples was Safety regs From: Rob Denney <proa_at_tpg.com.au> Date: Thu, 23 May 2002 08:14:38 +0800 To: multihulls_at_steamradio.com G'day again > Ted said > snip Harrigami is snip 25,000 ft lbs. Since it's 36 feet as a proa, I'd compare it to a 32 foot trimaran. My 32 foot tri generates 50,000 ft lbs, and I think that an F31 is in the same range. I would not like to take an F31 offshore with 1/2 of its righting moment. It would also not be very competitive in a fresh breeze, as you would have to reef early. You said in your previous post that the comparison was all about righting moment. Why on earth would you compare your 50,000 ft lbs tri to 25,000 ft lbs Harrigam? Equally, why would you compare a 38' (not 36') boat to a 32 footer? A more relevant comparison would be cost. What do the materials in your tri cost? How long does it take to build? Two parameters (length and rm) is a better way of analysing performance than one (rm), but you are still being selective, and consequently only telling a small part of the story. The rest of it would be something like this (please correct any wrong figures) I suspect your tri has about 2.5 times the weight, less than double the upwind sail area, 15% less waterline length, 25% lower l/b ratios, double the wetted surface, double the air drag and 5 (10?) times the cost, compared to harrigami. The tri is much heavier, has a bit more sail, is shorter, draggier and more expensive, plus it has more rm. Using these numbers, perhaps some of our number cruchers can tell us which boat is faster in theory? The tri also has the benefit of 40 years and thousands of boats worth of development. Relatively speaking, Harrigami in racing format is still at the development stage of Piver tris. This is the whole point about proas in general, and harry proas in particular. They don't compare with conventional multis any easier than conventional multis compare to monohulls. Therefore, all we can do is list the benefits, take people sailing, do the miles and get some race results, to enable comparisons to be made. Trying to denigrate them by numbers is a pretty futile exercise. Regards, Rob > _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Making trimarans faster was Safety regs From: Rob Denney <proa_at_tpg.com.au> Date: Thu, 23 May 2002 08:20:20 +0800 To: multihulls_at_steamradio.com > G;day, Sorry, this does not contain tips on how to spend thousands of dollars to get that extra 0.05% speed advantage. It is in reply to Ted's post about the drawbacks of Pacific proas. > Ted said > snip Get enough weight in the windward hull and it begins to sail like a dog ... oops I mean cat...in light air. Interesting. This is exactly the problem trimarans have, except it is the middle hull not the windward one where the weight goes and which we want to fly for optimum performance. The answer, in both cases, is of course to design the load carrying hull accordingly. > snip Width optimizes the weight available and still allows for performance in light air if you keep the accommodations out of the log. Assume that a beach cat was sailed by a crew in a fixed position. Which would be faster in winds from 0 to 30 knots? Locating the crew on the lee hull and leaving the beam the same Locating the crew on the lee hull and increasing the beam Locating the crew on the windward hull and leaving the beam the same. Russ Brown advocates #1, Ted is suggesting #2 and I reckon #3. Any comments from anyone else? Instead of thinking about proas as coconut logs and crabclaw sails, think of them as double ended trimarans with unnecessary appendages removed.. Atlantic proas: A tri with the windward hull thrown away and replaced by the middle hull. Pacific proas: A tri with the lee hull thrown away and replaced by the middle hull. Harryproas: A tri with the rig in the lee hull, and the windward hull thrown away and replaced by the middle hull. Any comments on which is likely to be fastest? Cheapest? Beam stays the same in each case. In reality there are numerous structural advantages to two way boats. There are also disadvantages with double ended hulls, rigs and steering, but these are rapidly being solved as we gain experience. regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Stability and safety regs From: Rob Denney <proa_at_tpg.com.au> Date: Fri, 24 May 2002 08:32:00 +0800 To: multihulls_at_steamradio.com > G'day, > Tim said > Rob Wrote: > > 4) Taking righting moment in isolation of other features (weight, >> length, sail area, even cost and space) is as illogical as taking any >> other parameter in isolation. > > Hi Rob and all, > I understand that multihull stability is 1/2 Centreline Hull beam x > sailing displacement. (Refer to Chris White's book on multihulls) > Rob > This is correct for symmetric boats which have alternate sides to windward, (weird concept, I know, but apparently it makes sense to a lot of people ;-)) but for assymetric ones which always have the same side to windward (proas), it is easier to use mass of windward hull * cl-cl beam. The numbers I used were for the racing version, currently being built. The 600 kgs weight in the windward hull includes 4 crew (for the rules), the hull, half the beams and tramp, plus full fresh water tanks, which we would carry if it was a windy day. Please note. This is not water ballast, which is illegal. > > > Tim > My point is that you can't beat width and weight to be more stable, and > so less likely to capsize. Configuration doesn't matter, snip Stability also > equates to power to carry sail, and so speed upwind and reaching. Sure there > is a power to weight relationship, but waterline length and power to carry > sail usually dictate who is first to the top mark. > Rob > And my point (#4 above) is that there is more to it than just these numbers. You are up to three parameters (rm, weight and length) which tell more of the story than Ted's two (RM and length), but still not all of it. > > When comparing boats, I think the sail area of the boat should also be taken into account, as well as the air and water drag, and the cost and space. Imagine one of the boats you describe (long and powerful and light when built) also being full of heavy cruising junk, with commodious, full width bridge deck and dinghy hanging off the davits, plus 20 passengers sitting around the deck. Or, at the other extreme, can you beat a Tornado (rm ~1200kgm sa 20 sqm, loa 6m) upwind or reaching? > > Waterline length and the ability to carry lots of sail are not the full story for a fast boat, although I expect that boatbuilders, sailmakers, rig salesmen and fittings suppliers wish that they were. It is very easy (and hellish expensive) to just keep adding sail and righting moment to get a fast boat. Takes a different approach to make them fast with less sail area, and lower cost. > Tim > snip > I assume these dimensions are for the next one, as the Hg as pictured > doesn't look that wide or have mast that tall? The challenge will be in > having the stability to use the power of a rig that tall. I have similar > mainsail luff dimensions and run out of 'stability' at much over 15 knots > true, ie 23 knots across the deck. > Looking forward to your race results, and good luck with the project. Rob Thanks for the good wishes. Going to need them, I think. The dimensions are for the current, work in progress proa (new beams, rig and interchangable ww hull), which I hope to be racing. It will run out of stability at way less than 15 knots true. The plan is a) for the unstayed mast to bend just before the hull lifts in gusts, thus enabling full sail limits to be the lulls rather then the puffs. and b) Once the lulls are too strong, we hope to be able to reef quickly and efficiently, and not have any mast sticking up without sail on it. First reef should get us up to 20 knots true, deep reef up to 30, anchor and carton of beer after that. The height of the mast is for light air performance, same as for your boat. The trick is to lower the weight and remove the windage of the top section of mast when the wind increases. Will it work? Probably not the first time, but when/if it does, it will open a whole bunch of options for rigging boats. It is also fun and very challenging, which are the reasons I am playing with it. Incidentally, we don't plan to have a headsail. At least not until someone overtakes us in the light! regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Stability and safety regs From: Rob Denney <proa_at_tpg.com.au> Date: Fri, 24 May 2002 14:21:13 +0800 To: multihulls_at_steamradio.com > G'day, Ted said > You can perform the thought experiment of sailing your trimaran at speed and then having the leeward beams break. What happens? That's right, the boat capsizes snip > Now think of the other example. You are sailing with a friend's identical trimaran. Your windward beams break. What happens? You now have less weight and windage and you will sail away from your friend. Well, there is one little detail, and that's that the > > lazy ama is in a favoured position to generate righting moment. If you were both at your limits, then you would capsize. So it's not so simple, does the additional sail available to a trimaran pay for the weight and windage of the lazy ama and 1/2 beams? I don't know the answer to this analytically, but my guess is that it's a wash. > Rob, This is a lousy analogy as these would be very narrow proas. A far better thought experiment, inasmuch as it measures what current proas actually are, is to leave BOA the same and swap the hulls around, as per my earlier post. i also don't know the analytical answer, but I can tell you this from experience. Harrigami, with an awful set of sails (Tim has seen the photos and will verify this) does 16 knots (gps) in 16 knots of breeze (Met Bureau). I don't doubt that Ted's tri and the F boats would exceed this. However, they are at the end of their potential and cost megabucks, Hg is at the beginning of it's potential and cost peanuts. Have any of you F boat guys got any actual numbers for this breeze, under working sail? Just to give me something to aim for with the new rig. Footnote: Some of us have been banging on about proas on this list for some time. It is interesting to note how attitudes are slowly changing. A few years ago, proas were effectively banned from the Mhml and started their own list. Despite this, a few of us would occasionally chime in on mhml and get shot down in flames. This has become less common. In fact, in this thread (so far!) the only negative comment about them has come from Ted. There have been numerous positive comments, and a lot of encouragement, both on and off list. I would like to thank the list members for their enthusiasm, broadmindedness and support. I look forward to taking any of you for a sail if you are ever in Western Australia. regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Stability & Safety Regs From: Rob Denney <proa_at_tpg.com.au> Date: Fri, 24 May 2002 14:25:29 +0800 To: multihulls_at_steamradio.com G'day, Tim said > Rob Wrote: > snip Ditto the NZ regs, but I > > have already been refused entry for a proa (solely because it was a > > proa) in the Coastal Classic in the past. > > I very much doubt the above is true Rob. And an unnecessary swipe at our > honorary safety inspectors. Rob Sorry mate, it is true but has nothing to do with your esteemed inspectors. I was not refused inspection, I was refused entry. The refuser was my (still) very good friend, NZMYC Commodore (at the time) Jason Segar, the person who has done more for multi sailing in NZ than anyone else apart from Malcolm Tennant and Peter Blake. Jason visited while we were completing W (a radical cat which makes proas look positively normal). We were contemplating knocking two half hulls out of the W hull mould, and using the rig and beam off W to build a 15m/50' proa and have a go at the Coastal Classic. Jason's refusal was point blank, and he said it would apply regardless of how many miles we did before the race, and us being accompanied by a safety boat would not change his opinion. He absolutely knew proas were unsafe and that was the end of it. On the basis of his inflexibility and his standing in the multihull club, our intended sponsor threw in the towel. regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Re: [MHml]Tack or Shunt From: Rob Denney <proa_at_tpg.com.au> Date: Fri, 24 May 2002 14:27:15 +0800 To: multihulls_at_steamradio.com > G'day, > Bob said > Rob, if your EasyRig design progresses to the point of being a true free > standing rig would there be any major consequences of being backed by > the wind? One could simply resume the tack in your now Atlantic proa > until the speed builds enough or space allows a tack back to the Pacific proa configuration. Rob Absolutely. Even the current configuration allows the rig to backwind until it is pointing athwartships. At this stage, we swear, rotate the rudders 180 degrees and sail off in the othe direction. Costs us a few boat lengths and a lot of face, but is almost effortless. Doing the Atlantic/Pacific switch is another option, but involves a second mainsheet to hold the rig from the "wrong" side. Bob > Taking this to the extreme, marketing could sale a low cost option for > an Atlantic proa if someone was concerned about owning a Pacific proa. > Another option could be to take off the accommodation hull and slip on > another rigged hull with EasyRig to provide a bi-plane catamaran. Rob > Could do. I already have a choice of racing and cruising windward hulls. The drawback of having two equal hulls is that the weight, stresses and costs all go up compared to a relatively small hull always to windward. Having said that, I think a cat with unstayed rig(s) in the hull(s) makes a whole lot more sense than having a highly loaded stayed rig in the middle of the boat, the area least able to support it. > > Bob > PS Keep up the good work! Rob Thanks. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: [MHml] Re: balsa From: Rob Denney <proa_at_tpg.com.au> Date: Sun, 2 Jun 2002 09:47:20 +0800 To: multihulls_at_steamradio.com G'day, John Perry said > I for one would be interested to read details of this and/or similar tests, > would anyone have any literature references for test methods and/or results? We did a bunch of these tests to convince the authorities to allow strip planking for survey boats. The accepted laminate was 20mm (3/4" in those days) H80 foam with roving and csm each side (different amounts) in polyester. We made and tested samples of foam/glass/epoxy, wood/glass/epoxy and DuraKore/glass epoxy. As Richard said, the foam was the worst in all the tests. Convincing the authorities was hard work, I was involved in 4 lots of these tests. The upshot was that cedar and Durakore strip planked boats were accepted for surveyed boats, at a lower panel weight than the foam boats. We also did a bunch of 3 point bending tests at various laminate angles. Again, the cedar and the D/kore were superior. What was most remarkable to me was how good the csm was at dissipating the energy. Without it, the foam (Airex and Divynicell) performed very poorly. They have since changed the rules, so I doubt that there are any records available. Even if there were, you would get a lot more information by making and testing your own panels. Or you can ask the manufacturers. Each has the results of numerous tests showing there product is superior! All the laminates were far heavier than they would have been for non survey boats. The impact tests only showed the unsupported panels resistance to heavy round objects falling on them. The 3 point bending tests were particularly unfair on the relatively low compression strength foam cores. The argument on balsa as a core is pretty silly. Trying to make a case that it wil rot if not sealed is about as meaningful as pointing out that windows will leak if they aren't sealed. Balsa is an excellent core when used properly. This means sealing it. Balsa is also now available at the same weight as foam (80 kgs/cu m). It takes far less energy to grow and transport balsa than to make and blow foam. Balsa is bio degradable, foam is not. Balsa is far cheaper and less damaging to the environment to produce. If it is expensive in America it is due to the same factors that makes WR cedar more expensive (according to Ted Warren) in America than it is in Aus. Somewhere along the line, American boat owners are being ripped off more than aussie boatowners. All the balsa boats with problems are production boats. Hence they and their foam equivalents use segmented cores. These almost always have voids running through them where the core is not properly filled. Until quite recently cores have not been vacuumed onto the outer laminate, making these voids almost unavoidable. I once removed an unsealed skin fitting from a segmented foam boat. Water was still leaking out 2 weeks later. The smell was awful. The foam around the fitting was mush. The owner eventually got sick of waiting for all the water to drain out, put the fitting back and sold it. This doesn't make foam a lousy core, it indicates lousy boatbuilding. The first 2 Durakore boats in the world were a 36' (fate unknown) and a 40' mono, (still going strong when I saw it a cople of years ago). The third, which I helped build 15 years ago, is a 26' trimaran, which has had a very hard existence. It is still one of the fastest boats in Aus. The luan skins on the Durakore are 1mm thick, (normal is 1.5), and the laminate 200 gsm (6 ounce) unidirectional glass. Despite being raced hard by a succession of cowboy owners, this boat was still in perfect nick when I saw it 12 months ago. The only people who need to fear balsa are the ones who employ crappy boatbuilders or use lousy building techniques. Finally, Verbatim was not built by Graham Bird. He sold the balsa, the resin and the technique to the F25 guys. Verbatin was long grain balsa, built the same way cedar strip boats are. It was way cheaper than using end grain balsa, or foam. We put a skin fitting in it below the water line after 3 years hard use. The balsa was dry as a bone. A tribute to the care with which Ian Johnson built and maintained it. Peter Schwarzel is an very knowledgable and painstaking composites engineer, as well as a friend of mine. To suggest that he should hand back his degree is an unwarranted insult, by someone who admitted he has little knowledge of the subject. I have trashed the originals, so I have no idea who said what, but this covers some of the points which I thought were were wrong in this thread. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Re: balsa From: Rob Denney <proa_at_tpg.com.au> Date: Sun, 2 Jun 2002 23:11:12 +0800 To: multihulls_at_steamradio.com > G'day, Ted said > Rob Denney wrote: > > > The accepted laminate was 20mm (3/4" in those days) H80 foam with >> roving and csm each side (different amounts) in polyester. > > I doubt whether anyone is building a composite boat this way today. Rob So? if you wanted to build a boat to survey in Queensland, this was the laminate you had to match the impact and 3 point bending properties of. Cedar and balsa both did, at a lighter weight. > > Ted > I can't figure out DuraKore. The mahogany laminate is not the final skin > since it doesn't extend laterally. So 1) You can't fair it by sanding because > of the mahogany laminate and 2) you still need a skin over the D/K. I know that Ocean Surfer came out overweight because of the need for a fairing layer over the D/K. Rob > Nonsense. The amount of bog required to fair the planks on even a seriously rounded boat like OS would be less than a couple of kgs. There is no reason why the edges of the face timber cannot be sanded, particularly away from areas of high longitudinal loads. OS may have had too much bog applied to fair the planks, but it did not need to have it. And before you start quoting builders and designers, draw a 500mm dia semi circle to represent the deck and plank it with 25mm wide planks. Then knock up to 1.5mm off the outside edges of the planks, and see how far from fair it is. The interior gets a very thin 10mm dia fillet along the joins, but does not have to be perfectly fair. > DuraKore is not an "ultimate" boat building material. In thicker sizes it is lighter than cedar, and it is (or was when it was invented) easier to use than foam. It also allows the exceptional (compared to foam) compression, sheer and cost (in Aus) properties of end grain balsa to be utilised in a one off boat. It is also an excellent way of overcoming balsa's biggest shortcoming, it's ability to soak up resin, particularly under vacuum. D/kore is made in a press and uses 200 grams per sq m of glue. H80 foam uses anything from 250-500 gsm to fill the surface, cedar and nomex considerably less. > Ted > > Balsa is also now available at the same weight as foam (80 kgs/cu m). > > At a premium, and compression and shear values decrease significantly. Rob At 80 kgs per cu m, end grain balsa has higher shear strength (1.26 vs 1.0 MPA), higher shear stiffness (87 vs 31 MPA) and higher compressive stiffness (1210 MPa vs 85 MPa) than pvc foam of the same weight. > Ted > > It takes far less energy to grow and transport balsa than to make and > > blow foam. > > Do you have any numbers? Bio fuels like alcohol actually use more > BTUs from fossile fuel to plant, fertilize and harvest the crop than > you get from burning the alcohol. Rob What has this to do with trees for boatbuilding? > Ted > > Balsa is bio degradable, foam is not. > > The polyester/epoxy/glass is not biodegradable in any case. Having the core biodegrade > out of the laminate is the problem. Rob Epoxy breaks down under sunlight, fibreglass is already pretty close to silicon. > Ted > WRC is more expensive to buy because the large chains, such as Home Depot, > will not carry it because most of it is harvested from mature forests, not > a good ecological move. I don't know why endgrain Balsa prices are as > expensive as they are. Might be a tax on imports? I don't follow your logic on the large chains. Surely the fewer buyers, the cheaper it is? Where are the economies of scale in logging timber plantations? Maybe there is a tax on balsa, but most Australian balsa comes from Baltek, from Ecuador via the USA. Some came from New Guinea, which was way cheaper, and much less intensively produced, hence even less damaging to the environment. > Ted > I have a quote from one of the best boatbuilders and pioneers in lightweight > composite boat construction, Ted Van Dusen. "Balsa cored boats make > good one year boats". Rob Big deal. Eric Goetz, _the_ best big boat composite builder in the USA thinks balsa is pretty good stuff. > Ted > Verbatin was long grain balsa, built the same way cedar strip boats are. > > Wow, you can't make the argument that synthetic cores are inferior > because of compression strength and also say that Verbatim is great with > longitudinal Balsa. I have a compression proportional limit of > 50 psi for 6 lb Balsa (USDA numbers), perpendicular to the grain. Rob Which goes to show that there is more to designing and building boats than materials numbers! It is all too easy to go with the latest wonder material (soon to be Duflex, currently Corecell, before that, DuraKore, before that pvc foam, end grain balsa, cedar strip and double diagonal), select "suitable" properties and then blithely state that this is the only material that will do the job, presumably in the hope that one will be recognised as a state of the art builder/designer. However, a bit of analysis, a few tests and some lateral thinking will often come up with a technique which is lighter, cheaper and easier to build. All these applied to balsa strip vs foam (the designers choice) in Verbatim's case. Verbatim was pushed harder than most, and did more miles than most. The structure gave no problems at all. Ergo, long grain balsa was an excellent choice, despite it's inferior numbers. The trick is in choosing the right material for the job, then building and maintaining it correctly, as opposed to blindly following what everyone else is doing. > Ted > Given the variety of boatbuilders, for example TPI, that have had > problems it's a bit hard to place the blame on technique. Your logic is flawed. If some builders have no problems with balsa, and some do, it is a building problem, not a materials one. FWIW, I like and use foam, balsa, nomex, paper honeycomb, cedar, pine, plywood and polystyrene as cores. Each has it's place, none is the absolute best. Anyone who uses one core throughout a boat, is not optimising the structure. Ted > If I had to choose > between a core that had to absolutely stay dry or it disintegrated or one > that was tolerant of leaks, the choice is easy for a marine environment. Rob Obviously, everything else being equal. In the cases I mentioned (cost, impact resistance, environmental soundness, 3 point bending), everything else is not equal. I am not saying balsa, or anything else, is always the best core, only that, used properly, it is not a problem. Dave said It's cool to use "natural" materials, whether or not they use more petro-energy than foams (balsa does). Rob Be interested to see your numbers. My comments are based on the very small amount of fuel required to plant and harvest balsa trees in a non intensive way, and to dry it in solar powered kilns. Whether Baltek does this or not is immaterial, they could do so. And what about the carbon sink properties of trees? > Regards, Rob > > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Re: balsa From: Rob Denney <proa_at_tpg.com.au> Date: Mon, 3 Jun 2002 07:53:14 +0800 To: multihulls_at_steamradio.com > G'day, Probably Riverside Oaks, the 26' Grainger tri I mentioned in a previous post. Graham owned the boat, and supervised the construction and a video. As well as being very quick, it is a remarkable boat in many ways, including it's high cost. It is still in excellent condition, and was leading (or nearly so, can't remember) the Brisbane Gladstone last year before dropping it's mast. Regards, Rob > I missed this bit: > In the video Graham gave me, the boat I referred to was built with durakore. > Whether it was Verbatim (Is that the same boat as BullFrog? I'd swear that > was the name) is in question. I *know* the product was durakore because > Graham, whom I spent quite a bit of time with both for my project and > outside it, was doing a hard sell on it to me for my F9A. Not too hard, > though, because he then sold me the divinylcell ;-) and rolls and rolls of > carbon. > > -Rob H > > > ----- Original Message ----- >> Rob Denney wrote: > ... >> > Finally, >> > Verbatim was not built by Graham Bird. He sold the balsa, the resin >> > and the technique to the F25 guys. Verbatin was long grain balsa, >> > built the same way cedar strip boats are. > .. > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] righting moment (was Safety regs) From: Rob Denney <proa_at_tpg.com.au> Date: Tue, 4 Jun 2002 11:36:40 +0800 To: multihulls_at_steamradio.com > Yo Joe, Well spotted. Just checking to see if anyone actually analyses my posts! ;-) . Seriously, though, my apologies for inadvertently misleading the list. Thanks for the numbers on Russ' boats. Any idea where Jzerro is at the moment? For those who are interested, Jzerro is the modern pacific proa which proves the type are capable of long distance offshore passages. It has sailed from Seattle to Brisbane (AUS) via LA, Tahiti and Noumea. looking at the rm numbers, it also proves that there is more to sailing offshore than high rm. Regards, Rob > Awhile back, Rob Denney wrote: >> >> 6) You ask for righting moments and comparisons. Sure. >> Harrigami(Hg) has a righting moment in racing trim of 36,000 kgm >> (6.5m beam, 600 kgs in the weather hull). > > > Yo Rob, > > Off by a factor of ten, I believe? The correct value is 6.5 X 600 = 3900 kgm or > 28,200 foot-lbs. of righting moment. > > Kauri, Cimba and Jzerro all displace about 1,000 lbs. in the ama at rest, > fifteen feet to weather; ~15,000 foot-lbs. RM (2000 kgm), before water ballast > is added. Approximately half of Harrigami... > > The 21 meter design at seven tons displaces 3,500 lbs. in the ama, 28 feet > between centerlines; 98,000 foot-lbs. RM (13,550 kgm), before water ballast. > > Joseph > -- > http://www.JosephOster.com > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] RE Balsa cores From: Rob Denney <proa_at_tpg.com.au> Date: Tue, 4 Jun 2002 21:58:53 +0800 To: multihulls_at_steamradio.com > G'day, > Bob wrote > My understanding was that Verbatum was strip plank Cedar below the > waterline because Ian was worried about Balsa's longevity immersed... Regards Bob the middle hull was, the outer ones were all balsa. I thought the reason was so it could sit on the beach without damage. Maybe wrong. Probably a bit of each. Ian is a pretty cautious builder, and Verbatim was the biggest balsa strip boat built. The cedar waterline became immersed as the boat got older (bigger rig, more junk, ambitous to start with), and the skin fitting was in the blasa. The drilled out core had antifouling on the outside, and sat on my desk for awhile. Re the environmental soundness or otherwise of balsa: I have written to Keith Walton (fairly high up in Baltek, who sell foam and balsa, asking for his opinion. I will report when/if I get a reply. Note to Paul Verbatim getting waterlogged proves my point about needing to look after balsa boats. It was bone dry when ian sold it. Note to Ross Have a look at the main hull photo. Note to The Other Rob. My religion is "sail fast and comfortably, and don't spend much money doing so". I don't have a favourite core, much less a preferred one. Balsa and foam have specific properties which make them best in some situations. where both work well, as long as they are used properly. > > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Re: Diagonal stability. From: Rob Denney <proa_at_tpg.com.au> Date: Wed, 19 Jun 2002 07:47:44 +0800 To: multihulls_at_steamradio.com G'day, The List's longest address asks: > Not sure how we do this with a proa. Inflatable sterns? Rob replies You assume that proas pitch as much as cats and tris. They don't. Proas in general, and harry proas in particular have the following pitch reducing attributes: 1) Light weight/easily driven hulls resulting in a longer hull for given sail area. Both the longer hull and the lower/lighter rig reduce pitching. Harrigami is 10.5m/35' and carries 31 sq m/330 sq' of sail. Masthead is 10.5m above the water. 2) Very high prismatic coefficient, due to zero rocker (no maneuverabilty worries with 2 large rudders in a boat that doesn't tack). Harrigami has a prismatic of 0.73. A Wharram about 0.58, a state of the art multi about 0.65, I think? Not sure if this is linear or not, but if so, harry proas will have the same advantages over a state of the art multi as these do over a Wharram. I look forward to seeing if this has the same nullifying effect on Paul Nudd's seasickness as it did on my wife's. 3) No non-hull weight in the front and rear 25% of the boat, which is also of relatively small surface area. If however, you wanted to reduce pitching even more, then it is simple enough to make the lee hull longer. This not only reduces pitching and nosediving, it makes the boat faster as well. Of course, you could do the same with a cat or a tri. The difference with a harry proa is that the ends do not support any hardware (forestays, forebeams, rudders, stays) so the cost and weight added is minimal. You also do not add any space that can be filled with junk, and are extending one low, narrow hull, not two or three. Converting Harrigami (35'/10.5m for ease of trailering) into a 40'/12m container size boat would cost $Aus100/$US60 in materials, take 20 hours and add 10 kgs/22 lbs weight. Making it into a Transpac size boat (45'/13.5m) would take the same time, cost and weigh twice as much. The rig, beams and ww hull would stay the same in each case. Each would be faster than it's predecessor, except in very light air. Of course, there is no completely free lunch. Proas gain in pitch reduction but suffer from not having the weight concentrated in the stern. This makes them more prone to sailing bow down, although the other pitch preventers (long hull, high prismatic, low rig etc) work to reduce this tendency. With nothing on the ends,and narrow, tightly curved decks wave piercing/nose diving becomes much safer than on a boat with prodders, foredecks, forebeams and trampolines to trip over. regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Leeboards From: Rob Denney <proa_at_tpg.com.au> Date: Thu, 20 Jun 2002 08:01:12 +0800 To: multihulls_at_steamradio.com > G'day, Paul Nudd > Think Rob Denney used them on proa for a while but now uses 2 spade > rudders. > Comments Rob? Used a lee bord on U (pictures and details on www.harryproa.com). Section was a sector of a circle, able to be slid and rotated fore and aft, and rotate sideways. On a track on the gunwhale, water pressure held it to the side of the boat, although not always. Worked a treat sometimes, although as I could not see it, i moved it to the weather side. The flow across it was fascinating to watch, as was the way it would rotate forward, against the water flow when the aoa was correct. Also used rudders mounted on the inside of the lee hull on Harry. Disastrous due to lack of precision in the drum set up. The foils seemed to work ok, the mechanism blew bearings all over the bay, and was very draggy. W (12m free to pitch cat) has a board hanging off the middle beam. Works well, although there is nothing to compare it with. It has survived serious hammering on various occasions. I can dig out a photo for anyone who wants details. Lee boards have all the advantages mentioned, but I differ on the disadvantages. i reckon the drag from anything other than a very well sealed case outweighs that of a surface piercing foil particularly as the aspect ratio increases. Raking the foil forward, or fitting a fence will lessen the surface effects even more. The best reason for lee boards is that when (not if) you hit something, you don't tear a hole in the bottom of the boat. I have foam leading edge and bottom on my rudders, a fuse in the cassette system, enormously strong carbon rudder shafts (built for a much bigger boat) and very strong and well supported cases in a very light (low inertia) boat. I still think I am pretty stupid to sail around with such potentially fatal things hanging out the bottom of the boat. Like a few other things on modern cruising multis, daggerboards are an example of the racers leading the cruisers by the nose along expensive, dangerous paths. I use the spade rudders (no centreboards) as the shape of Harrigamis hull makes side hung rudders pretty messy, and there were already enough new things on the boat. The rudder cassettes are a tight fit in the bottom of the slot, but there is still a lot of gurgling going on, indicating loss of efficiency. If I get time this winter, I will be fitting very deep, narrow drum rudders. Even more stupid, but the boat is being reconfigured for racing, so performance is all. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Leeboards From: Rob Denney <proa_at_tpg.com.au> Date: Sat, 22 Jun 2002 20:26:16 +0800 To: multihulls_at_steamradio.com G'day, Tim and the list's longest address make the point that daggerboards help boats perform. I agree. My comment was that they are dangerous, and Tim and lla's attempts to justify performance at the expense of safety doesn't alter this. Tim > A well built multihull's centrecase will survive most impacts at > reasonable speed. Rob Making the boat strong enough and/or the boards weak enough (Tim addresses the difficulty of this in his follow up post) is easy to say, difficult, if not impossible to do. Hit something solid (semi submerged containers and logs spring to mind) with the leading edge of the centreboard at speed, in a well loaded cruising multi and you have a serious leak problem regardless of how well reinforced the hull is. > Tim > The benefits outway the risk to most or we wouldn't be using them. Rob maybe, but there is not a lot of rational risk analysis involved in boat ownership. There is a lot of "the racers use them" or "the designer/sales rep recommended them" and of course, "don't forget the resale value" to explain otherwise loopy safety decisions. One of these is daggerboards with the capacity to sink or seriously flood the boat when you hit something, head on, at speed. Others are: rigs which don't allow you to run dead down wind, traveller tracks across where people sit, capsizable boats without escape hatches, cruising rigs with a dozen or so potential weak points any one of which drops the mast, booms at head height or lower, boats which sink when flooded, etc. > Tim, > With leeboards, how are they secured to the hull? With a pin or bolt > through the laminate? A composite solution on the hull side would be in peel > I would think. Rob It is easy to knock "state of the art" leeboards, but if we unthinkingly accept the current way as the best, then we would all still be sailing monos. The first step towards improving things is accepting that the current standard (daggerboards) have shortcomings, then putting our fertile imaginations to work to overcome the shortcomings. Copying what every one else does will not make for improvements. FWIW, my leeboards had no holes, or laminates in peel. Ditto for the beam hung board on W. The lists longest address advises why not then make the hull into a leeway resisting shape, like a surf cat, and dispense with any type of board altogether. Rob Unfortunately, surf cats hull shapes don't resist leeway any better than your friend's Piver. On cruising cats, the idea has even less merit. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Leeboards From: Rob Denney <proa_at_tpg.com.au> Date: Mon, 24 Jun 2002 07:53:46 +0800 To: multihulls_at_steamradio.com > G'day, The lists longest address says > Mine are the similar. 2 x 3mm ply and 6 oz glass around a wood spar. > The cases are a 12mm ply and glass lamination made around the centreboards. > They are offset to the outside of the hulls and go through the chine log and > up through the cabin top. Hard chine ply hulls....... and We had several high speed impacts with solid bits of papa rock on the sea bed. The boat came to an abrupt halt each time but i have not yet > damaged anything more than my dignity and the tip of the boards. No idea what your boat weighs, but few cruising cats weigh less than say, 3 tonnes loaded and if we assume "high speed" to be say, 15 knots, and say 1m of board below the hull then these are a) remarkably strong bits of 2x3mm ply, and b) a remarkably strong case and chine log. I retract my remark that making impact proof cases on cruising cats is difficult. I stick with the need to develop alternatives. It would be interesting to know if any damage befell your crew during these "abrupt halts". Dumping the sheet on Harrigami slows the boat pretty quickly. At 15 knots if you aren't holding on or prepared, you get thrown to your knees. This is nowhere near as abrupt as hitting something solid, nor does the boat come to a halt. Does "halting abrubtly" at this speed lead to bloodshed? Regards, Rob > > _______________________________________________ > Multihulls mailing list > Multihulls_at_steamradio.com > http://www.steamradio.com/mailman/listinfo/multihulls _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Re: Multihulls From: Rob Denney <proa_at_tpg.com.au> Date: Tue, 25 Jun 2002 22:03:11 +0800 To: multihulls_at_steamradio.com > Joseph said > > Other than the good advice to "know your boat and pay attention", the greatest > hope, I would think, is a "smart boat" that takes better care of itself using > sensors and a computer, warning the skipper about impending doom and as a last > resort, sacrificing the mast to prevent overturning. Gotta have some major fail > safes on that plan though! Would be terrible to drop the mast by accident!! > Interesting you should mention this. The 12m cat I am helping design will have a biplane rig. The owner has a big problem with capsizing in strong breezes. We are going to try and build the masts so that, with full sail on one mast, the mast breaks before the hull lifts. He will still be able to capsize with both sails up, but hopefully will remove one before this happens. Should still be able to sail home on the remaining mast. Carbon mast design is still pretty much a "black" art, in terms of when they break. Where and how they bend is better understood, but making them break at a given load is a challenge that no one has really had to meet. For a start there can be no safety factors for the material, calculations or workmanship. These safety factors usually mean cruising boat carbon masts are 2-3 times heavier than they could be, so the biplane masts may be one third lighter and cheaper than they would otherwise be. Given that our new mast materials are costing $aus30 per kg, about the same as alloy extrusion, but much lighter and stiffer, he is going to get a very cheap, safe rig, although he may have to replace it a little more often than most, until he learns to sail within the limits. All in all, an interesting challenge. I have just finished the top half of Harrigami's new mast. 7.5m/25' long, bit heavy at 12 kgs/26 lbs, with the masthead crane the only fitting still to put on. Not far off prepreg/autoclave resin fibre ratios, using vacuum pressure of 1.5 atmospheres/22 psi. Looks a bit ugly (bottom half should be perfect, and even better fibre ratios, now the learning curve has levelled out), but performs as designed in static bending tests. Now I just have to sort out the telescoping side of things. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Multihulls From: Rob Denney <proa_at_tpg.com.au> Date: Tue, 25 Jun 2002 22:18:59 +0800 To: multihulls_at_steamradio.com G'day, Dave Culp asks .snip discover a short-handed 34' mono easily capable of 8-10 kts in 15 kts of wind, and fully controllable at 14-16 kts, in 25 kts of breeze. I completely believed its owner, who told of downwind romps at 22-24 kts, under main and jib alone, in 35 kts. And not in white knuckled, survival conditions, but on a Wednesday night beer can race! How many on this list own 34' multis, weighing less than 8,000 lbs and costing under $75k, which will meet this performance criteria? This is a STOCK monohull, and one not considered particularly extreme. Seeing as you ask, I easily beat 2 out of three. Fully expect to get the third (25 knots under working sails) with the new unstayed, telescoping carbon mast. Harrigami (35' harry proa) materials to sailing stage cost $Aus20,000/$US$11,000. Same again for pro builder to build it. Achieves 16 knots (gps) in 15 knots of breeze, flat water, singlehanded. Same with 4 on board. Above this the old mast starts doing very negative contortions. Hg weighs 550 kgs in sailing trim, and contains 2 double bunks, full headroom and ample space for galley and toilet. Positive righting moment to 70 degrees, and unlikely to pass 90, at which time it can be rerighted by the crew without getting wet, assuming they can crawl down the vertical trampoline! Hard, but probably not impossible to pitchpole a 35' boat with an 11m mast. Trailerable. NOT a stock boat, possibly the most extreme boat on this list :-) There might be an article on Hg in the next Multihulls Magazine, or have a look at www.harryproa.com In my limited experience of trying to sell non ordinary multis no one gives a stuff about Newick's impossible trio of speed, space or price, all of which harryproas provide, in spades. What buyers want is a boat that looks like everyone elses, or at least, not too different. People (sailors and non sailors, mono and multi) all talk for a long time about how Hg looks before asking about the speed, being surprised at the space and disbelieving about the cost. Safety and capsize possibilities don't usually get a mention till everything else has been discussed. Dave, good to see you getting some publicity from Yachting World. Suspect you didn't quite convince Matt Sheahan that kite tugs are viable! Sad to see you knocking the kiwis, particularly after your rant a year or so ago when someone "dissed" your home state of California. I think an apology is probably a good idea, before you are made to look even less in touch with yachting reality than you appear to be from your post. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Multihulls From: Rob Denney <proa_at_tpg.com.au> Date: Wed, 26 Jun 2002 21:57:50 +0800 To: multihulls_at_steamradio.com >> G'day >> Dave Culp > Nice advert for Harrigami, Rob. Hats off to you for your accomplishments, but these boats hardly fit the "typical cruising multihull" category this thread covers. Not an advert, just pointing out what my boat does, and what I hope it will do after some mods, in reponse to your very specific question. Isn't this what the list is all about? Be interesting to hear what Dave thinks it is about harry proas that prevents them qualifying as "typical multihull cruisers" (tcm)? Which of cheap, spacious, fast and safe(ish) prevents harry proas being what everybody in this thread says they want in a tcm? It defeats the purpose of asking about fast and cheap tcm's if you then define them as slow and expensive. If I was to build a slow, expensive, capsizable harry proa, would it qualify as a tcm? Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: Designed failure of masts; was Re: [MHml] Re: Multihulls From: Rob Denney <proa_at_tpg.com.au> Date: Thu, 27 Jun 2002 20:32:08 +0800 To: multihulls_at_steamradio.com G'day, Masts are free standing, with wishbones. May be telescoping if I can get them to work on Harrigami. You are correct about the wave loads, they added some complexity to an already complex subject. Reality is, he will probably go with a sheet release, as I doubt that my engineer will "guarantee" that the mast will fall before the boat tips over. Owner's worry about a sheet release was that it could be rendered inoperative by the crew. Regards, Rob rather than having a mast crash down on my deck, I would try to set up a release on the sheets which allows the sail to weathercock in those conditions. But, as with any safety device, if you don't have an over-ride the device itself may cause a problem (i.e. unable to get out of a situation because of the forces involved). > I assumed you are using boomless freestanding rigs, BTW. And this just occured to me... With the large acceleration forces generated > by a multihull sitting on the surface, how can you be sure the mast won't > come down due to wave action alone? > _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] List Etiquette. Footers From: Rob Denney <proa_at_tpg.com.au> Date: Thu, 11 Jul 2002 14:13:27 +0800 To: multihulls_at_steamradio.com > > Kerry, a very small amount of work can get your footer into meaner > and cleaner shape > snip useless advertising > Half the number of lines to say the same thing! > G'day, Or you could do what you have been politely asked to do, for very sound reasons, and cut out all the extraneous crap and sign off with your name and your web address, like everyone else does. No one on this list is going to send their boat to Whangerei to get it repaired. Anyone who wants to write, fax or phone you can get the info from your web page. Anyone who is in any doubt that you know everything there is to know about boat repairs and design and are prepared to discuss it just has to read your posts. What purpose does the footer/advertising serve? Your advert wastes band width, irritates the hell out of people who get the digest version of the list, and costs some people money to recieve. Joe asked you nicely to refrain. Stop being so arrogant and do so. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Carbon wing masts. From: Rob Denney <proa_at_tpg.com.au> Date: Fri, 12 Jul 2002 20:52:01 +0800 To: multihulls_at_steamradio.com > G'day, I have drawings and specs for carbon/epoxy hounds, head, foot and spreader fittings for wing masts which I have used on masts up to 12m long. Bonded in bolts and backing plates have been superceded by bonded on fittings reinforced with uni or tow as they are lighter, cheaper and less prone to problems. Contact me off list if you are interested. Silly to use any fudge factor. Get an engineer to do the numbers, (there are many cheaper guys around than High Modulus, and just as good. Let me know if you want addresses), check them thoroughly and then stick to what they say. Make sure the specs include static bending numbers and test for these before stepping the mast. Beefing up a carbon mast without being aware of what you are doing can cause problems, as well as increasing the cost and weight unnecessarily. You need diagonal fibres to prevent it twisting, to help stop the fibres buckling and to handle all the weird and wonderful stresses which develop when two materials as different as carbon and epoxy see serious loads. Carbon/epoxy loses half it's stiffness when it is 10 degrees off the load path. You need as much lengthwise fibre as you can get. Carbon properties are common knowedge, but not much help. You need to know the properties of what you are laying up. Resin fibre ratios, off axis alignment, fibre handling systems, resin properties and void content all come into this. Nearly there with the footer. Only 2 unnecessary lines now. regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
Subject: Re: [MHml] Re: [multihullracing] Australia 1 Raw Nerve 0 From: Rob Denney <proa_at_tpg.com.au> Date: Fri, 26 Jul 2002 11:37:13 +1000 To: multihulls_at_steamradio.com > G'day, > The solution seems pretty obvious. Forget the shrouds and go with an unstayed mast. Obviously not a solution for Raw Nerve, but sooner or later, surely, owners will see that stayed rigs are great for riggers, mast makers, chandlers and sailmakers, but a never ending cash drain. How many on this list have had masts fall down because of dodgy rigging? And even if it doesn't fail, it needs to be replaced every 5 years. We all complain about the costs of boating, but won't take the steps necessary to remove one of the most common and expensive failures. I commend Martyn for having a go, and wish him, Stuart and the crew success next time. Although I wonder about racing a boat across the Great Australian Bight in the middle of winter. The isobars down there last week were almost solid. 125 km/hr (60+ knots) was recorded at the sw tip of Aus. The safety issues raised after yet another capsize are also addressed by unstayed rigs. Just dump the mainsheet (no knot in the end and the sail swings head to wind, regardless of heading angle, or what the helmsman does. There are analogies to epoxy and gloves here. 20 years ago, everyone knew the stuff was dangerous, and what the solution was, but gloves "were for sissies, slowed you down, made it hard to pick up tools, etc". After users started breaking out in rashes and itching till they bled, common sense prevailed. I wonder how long before the same happens with rigs. Regards, Rob _______________________________________________ Multihulls mailing list Multihulls_at_steamradio.com http://www.steamradio.com/mailman/listinfo/multihulls
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