open 20 footer

Discussion in 'Sailboats' started by usa2, Mar 10, 2005.

  1. usa2
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    usa2 Senior Member

    if any of you were to build a 20 footer for the sole purpose of going as fast as possible both upwind and down while racing, what characteristics would you give it? When i say "while racing" that sort of rules out canting keels and other sorts of moveable ballast-unless someone can come up with a way to make it so the keel swings super fast and the thing can tack as fast as a fixed keeler. This is probably going to viewed as a rather vague prompt, but any input into it would be greatly appreciated.
     
  2. Paul B

    Paul B Previous Member

    Monohull only? Anything goes?

    Upsize the old unlimited Aussie 18 type. Huge rig, huge racks (30+ feet overall beam), modern Assy with prod, three beefy boys on the wire, and a chase boat.

    If you have to meet some capsize recovery requirement, same as above with as little lead as possible in the bottom of the board to meet the requirement.

    If not monohull, then downsize a rigid wing C Class cat?
     
  3. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

  4. CT 249
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    CT 249 Senior Member

    The canters seem to tack fairly quickly, but they are still (in absolute terms) dog slow compared to the expanded 18' skiff sort that Paul B is talking about. I've spoken about the possibilities with Rob Brown, former "world" 18 champ designer/skipper who had the most powered-up 18 of all (Bradmill about '87). She weighed about 60kg (hull), had about 43' of mast on hte big rig, and was up to 31' wide wingtip to wingtip in its Brisbane (open water) configuration. He actually reckoned that it was getting too big and unwieldy and the smaller GP boats were quicker. Then again, others who were there reckon he's wrong, and I think everyone reckons the current rigs (only 33' high or so) are waaay small.

    So it wouldn't be hard to build something like a slightly bigger 18 (several skiff designers reckon the extra length would be a major advantage and 20' is about right) with 37' or so of stick and 18-22' wings. While the Backman 21 type is rated similar in speed to a J/80, a 20' skiff would be beating Tornadoes and TP 52s, you'd have to think (ie in a series of Singapore last year even the 16' no-spin Taipan cats were starting behind a good Farr 52 and beating it home, and the 20' skiff would be a much faster boat). I saw one of Brownie's 18s race an Ultimate 30, it was embarrassing to see the 18 going 50% faster.

    Then again, I have to admit I'm biased because I see no real use for the sportsboat type....hell, Thompson 7s get blown to the weeds upwind by my 41 year old International Canoe and they don't have much more accomodation so what's the point?

    It's quite funny looking at the speeds of sportsboats. In Australia's biggest freshwater race, the first sportsboat home was a 26' Elliott; the design is getting on, but it's still faster than a Thompson 7 and Melges 24 IIRC. It finished in 3 hours 32 minutes. It was 45 minutes ahead of the 25' family cruiser/racers and cruiser/racer 1/4 tonners and similar boats.

    But the first cruising cat, a 23 footer from the '70s, finished half an hour ahead. The 49er was 32 minutes ahead of the sportsboat, a Sharpie (505 speed 19 foot dinghy modified from a 1928 design) was also ahead of the sportsboats. The 1960s vintage 14' non-spinnaker cats finished half an hour ahead of the sportsboats (in just 3 hours of racing) and there was a 1972 design 16' cat that finished ONE HOUR ahead. The big modern cats were even further ahead.

    Given the fact that sportsboats are so slow compared to truly fast boats, why do people bother to make all those compromises in comfort, accomodation, fleet racing, offshore ability and economy? What is special about a 24 footer that can't cruise, can't go offshore, and gets beaten by a Hobie 14? I'll never really understand it.
     
  5. Doug Lord

    Doug Lord Guest

    Speed

    If you want ultimate speed then you can't beat a foiler. You have an 11'(12.75' overall) Moth already beating A class cats, 49'ers and Rohan ( International Moth Class World Champion)thinks he is faster than an F 18 multi.If you build a larger version of a two foil dinghy with a high speed rig you'll be faster than any current multi or mono...[20' and under -for sure- and maybe faster than many larger boats]. Except, perhaps if you built an all carbon larger version of the Rave.
    But the"bi-foiler" has an edge in lower and mid range winds, I'd bet.
    If you want a fast keelboat than a canting keel is a must. You can use an electrcally powered canting keel for ease of tacking and wings to get the crew out-very fast for a lead belly..
     
    Last edited by a moderator: Mar 11, 2005
  6. CT 249
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    CT 249 Senior Member

    Doug, what are you counting when you call a Moth 12.75'??? OK, they have a rudder frame but no-one counts them - otherwise we'd have to change I-14s to I-15'3", 12' skiffs would become 13'6" skiffs, 18s woould become 20s, A Classers would no longer be 18', Int. Canoes would become 25 footers when the tiller extension was flicked out the back.....Just as in conventional boats, bowsprits and rudder frames don't count.

    You may well be right about the foiler being the fastest. It's also possible that things may also change at the higher speeds big skiff-type boats travel; for example many skiff and dinghy designers looked towards narrow Moths as being the way to go for an unrestricted big skiff, but the guy who probably knows best (a narrow Moth designer and world champ who is also a top skiffy) reckons it wouldn't work because while the Moth shape creates incredible performance for an 11' single-sail boat, it doesn't have the top-end pace you need for a skiff downwind in a breeze.

    Perhaps...just perhaps; the same may apply to a foiler in skiff types? It may be like windsurfers, where the foilers aren't any faster than the conventional boards. There would also be significant handling problems in a 20' foiler moving at Tornado + speeds.

    If Rohan regularly beats As, he will be faster than an F18; the two are very similar in pace.

    Why is a canting keel a "must" for a fast keelboat? Konica Minolta beat Skandia in its last 9 races or something, AFAIK Full Pelt is getting wasted by the Formula Libera boats. And can you use an electrically-powered canting keel in a "normal" race? Stored power is still banned, isn't it?
     
  7. usa2
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    usa2 Senior Member

    Canting keels are not a must for a fast keelboat. One reason i suggested at the top that canting keels and other forms of moveable ballast not be considered in this is that its been proven that the performance increases on small boats are marginal and it really isnt worth it. The Cone of Silence was killing the similar sized canters and even threatening larger canters down under a while ago. Also, i mentioned something about racing these things. Since at 20', it wouldnt be an offshore boat-where the canting keel makes the most difference. And batteries are heavy. Why bother with them on a 20 footer? In this case the negatives of a canting keel outweigh the positives. Foils i dont think are feasible for this type of boat. Also, the type of sailing i would want to do doesnt involve flying. I admire the flying Moth guys, but thats not the type of boat that i would want to sail/fly. So, as most of you have said, basing this idea on an expanded Aussie 18 would probably be the way to go.
     
  8. Doug Lord

    Doug Lord Guest

    speed

    Chris, we're in the early stages of monohull foiling and Moths have set the pace by using a revolutionary foil system-just two foils with automatic altitude control. It would probably be naive of us to think that the technology won't be improved and much faster on larger boats.
    I think a well designed two person foiler(not a conversion) would take anything 20 feet and under and probably most things over 20 feet...
    The Moth class has been a real development treasure trove for monohull foiling because over 50% of the top Moth speed is due to technique. Some of the other conversions-boats not designed as foilers but trying foils nonetheless will not benefit from the intense competition in the Moth Class unless maybe they form some sort of "sub-class". But new one design wannabe foiler classes will emerge-sooner rather than later I imagine.
    I can't see how anyone could possibly consider anything but a monofoiler or multifoiler if they wanted max speed but they'd better plan on building at least two boats to get the thing worked out because without good technique a foiler is as slow as a seahugger....
    As to canting keels: I think if you put any well designed well sailed 55° canting keel boat up against a similarly well designed fixed keel boat the same length the ck boat will win. As best as I know when KM and Skandia raced Skandia was limited to a keel angle that would heel the boat no more than 10° at static-which for a canter is like fighting with one arm.
    But the subject above was small boats and if you want a fast 20' KEELBOAT then you want a canting keel, wings and trapezes. It makes no sense to me to carry around a bunch of lead that is just hanging under a boat being sailed flat.
    As far as I know, if the class rules allow it then a boat can race using stored power-like Schock 40's and ,of course, the big boats that almost all have diesel hydraulic systems.The great thing about an electric system on a small high performance keel boat is that you could operate the keel remotely with a wrist band transmitter(thats not limited to small boats though). I think canting keels can be practical at any length in which there are fixed keel boats, so ,say 12' and up.
    =============================
    Your question about 12.75' for a Moth: thats the overall length according to John Ilett and is critically important for assesing the Moth's foil performance since the foil footstep is important and the boat actually sails on the rudder foil.It's only of real relevance if you're trying to technically compare a Moth foiler to a similarly sized foiler OR you want to know how long it REALLY is.......
    =============================
    USA2, you said you wanted max speed-sticking with a partial sea hugger like an 18 is your choice but definitely not the fastest!
    Look at the 79er on http://www.Bethwaite.com
    ;thats the best way I can think of to carry lead around. Your comparisons to Cone of Silence are no where at all: the designer of the canters had a long treatise on that(Sailing Anarchy a few weeks ago); to infer from the results of that one race between totally unequal PROGRAMS that a fixed keel boat is faster than a canter is wrong. On a performance keelboat like the K6 you could eliminate one crew member with a canting keel; the same parallel holds true on any small keelboat: you can reduce weight and /or increase RM by ditching the fixed keel and it's even more important on a small boat (as I said above) because it is being sailed flat.
    As to using electical power- you'd still be ahead of the game because a relatively small battery would work BUT you don't have to use power: one of the guys earlier mentioned that the keel on the Backman 21 comes over manually with the speed of the jib in a tack.
     
  9. usa2
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    usa2 Senior Member

    Lorsail-
    Both types of boats each have their place, obviously. I dont think the canting keel is neccasary on a 20' boat- just adds to the expense. Yes its true that you can dump a crew member because of the righting moment gained by having canting keel, but then you have to have one of the crew remaining on board multitask and work the keel along with whatever else their responsibilities would be. I would rather prefer to keep a pair of arms to do something productive on board, especially since off the wind with an A-sail it would have rather strong forces acting on the sail.
    I also said that i wanted this theoretical class of boats to race. That means that upwind performance is important, along with tactics. IF you have a small battery, in most cases you might drain it if you get in a tacking duel, and thenyou really have a problem. Or, as in the Backman 21, you can do it manually, but since you said you would lose a crew member because you dont need them, this will still be a problem in the end. You seem to be strongly in favor of the canting keel system, which is fine, but if you are supporting the technology from a biased standpoint, you may be overlooking problems which can arise. Have you ever considered match racing 2 identical hulled boats-one a canter, one a fixed keel- both same displacement, both same sail area? What would you expect to happen going upwind? downwind they would be similar speeds, but upwind is where the superiority of one boat or the other would become apparent.
     
  10. Doug Lord

    Doug Lord Guest

    speed or?

    There have been numerous examples of racing between canting keel boats and fixed keel boats; one of the most important that I know about is the maxZ86's one fixed keel and two CBTF-the canting keel boats won.But there are many ,many examples if you do the research that prove the general superiority of a canting keel boat .
    But like in anything else there are always exceptions: poorly sailed foilers can be beaten by seahuggers; poorly sailed or designed canting keel boats can be beaten by better fixed keel boats.
    -------
    2, I'm curious: in your original post you mentioned max speed; I'm just wondering why you would exclude foilers assuming,lets say, that they would be even just 15% faster than an 18? Thats the estimated speed advantage of a little Moth foiler over a 49'er. But still the speed is likely to be even greater so for max speed around a race course why would you exclude them?
     
  11. CT 249
    Joined: Dec 2004
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    CT 249 Senior Member

    Doug re "It would probably be naive of us to think that the technology won't be improved and much faster on larger boats."

    I agree, that's why I SAID that it was only "just perhaps" that a non-foiler would be faster.

    Re "The Moth class has been a real development treasure trove for monohull foiling because over 50% of the top Moth speed is due to technique."

    Sorry, what do you mean by that?

    Re "I can't see how anyone could possibly consider anything but a monofoiler or multifoiler if they wanted max speed but they'd better plan on building at least two boats to get the thing worked out because without good technique a foiler is as slow as a seahugger...."

    Well, there you go, two superb reasons why you SHOULDN'T consider a foiler. One, they are still unproven (will the techniques of a foiler work at 20'? 18' skiffs and similar boats are quite different from Moths to sail....), secondly you have to come up with twice the amount of cash and twice the amount of time to build them, find twice the space to keep them, and find much more than twice the amount of time to learn how to sail them.

    "As best as I know when KM and Skandia raced Skandia was limited to a keel angle that would heel the boat no more than 10° at static-which for a canter is like fighting with one arm."

    Yes but wasn't Konica also limited in heel for her water ballast??

    "But the subject above was small boats and if you want a fast 20' KEELBOAT then you want a canting keel, wings and trapezes. It makes no sense to me to carry around a bunch of lead that is just hanging under a boat being sailed flat."

    Have the Formula Libera class tried canting keels? How did Full Pelt go against the non-canting Liberas?

    "As far as I know, if the class rules allow it then a boat can race using stored power-like Schock 40's and ,of course, the big boats that almost all have diesel hydraulic systems."

    Yes, but you have to have a class first, and the big boats race under IRC.

    Re Moth LOA; the rudder is critical for just about every boat, but no other boat measures the rudder so why a Moth? You are the only person I've ever heard who described a Moth as a 12.75 footer, the class doesn't. A 14 has a foil on its rudder but it's still an Int 14, not an Int 15'4". A 12' skiff wouldn't go without a 14' permanent kite pole, 2' transom extensions and a 2' rudder, but we don't call it a 28' skiff. An Oppie is more than 8' long with a rudder, but we don't change its LOA.
     
  12. Doug Lord

    Doug Lord Guest

    CHris, none of the boats you mentioned SAIL on their rudder foil!(except the Moth) So, if comparing a Moth foiler to another similar foiler the overall length can be important.
    Saying that monofoilers are unproven is absurd! Rohan has seen to that. I believe that any new boat can benefit from two boat testing if thats practical in development. The most important consideration in a foiler is learning the techique required to sail it fast. You'll learn that faster with two boat testing but you can learn it over a longer time if thats not practical.
    According to Rohan, if I remember correctly, the Moth has been improving at 10-15% per year since the first giant leap. For instance a year or a little more ago Rohan couldn't keep up with A class cats upwind now he can and expects that in a while he'll(The Moth foiler) be faster upwind. Rohan invented the technique of sailing heeled to weather on a foiler and a number of other techniques important for foiling fast. So you can do it alone but you'll make faster progress toward getting the most out of a new type of boat with racing as in the Moth class or in two boat testing if you're developing a product. Even with a souped up 18 sailing alone would drag out the learning curve not eliminate it-which was my point.
     
  13. Paul B

    Paul B Previous Member

    How many boats of ANY size has your 16 foot wanna-be-foiler taken on?

    Using the "logic" that you continue to spew, you have "proven" that foiling cannot happen at this size range.

    Here's the challenge: I'll go down the road and buy the used 18 that's sitting waiting for a new owner. I'll graft on 2 feet to the back. You build up a monofoiler 20 footer (or graft 4 feet onto your existing wanna-be). We'll meet up one year from today and see who wins.
     
  14. Doug Lord

    Doug Lord Guest

    race

    Sure "Paul B", but I won't need a 20 footer. See you at Kelly Park, Merritt Island Fl. March 11, 2006 . And I'm sure you'll show up!
     

  15. Paul B

    Paul B Previous Member

    What is this fixation on 55°? Why is it repeated over and over again in your posts? Why not 57°?

    Is it possible that you simply glommed onto that number because you "read it in a magazine" in a report about one single boat? We all read magazines. Some of us don't take everything written there as gospel.
     
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