Fastest boat for given sail area

Discussion in 'Multihulls' started by Brorsan, Mar 7, 2011.

  1. Brorsan
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    Brorsan Junior Member

    Been wondering for some time wich would be the fastest alternative for a given sail area, cat, tri, slim mono? Sudgestions?

    What i think i know and please correct me if i'm wrong(or rather what i think i have heard): a tri will be faster than a cat of similar leangth, but cat can be made bigger for the same amount of money invested.
    Slim monohulls can be pretty fast with small sailareas, maybe a thin mono canter could be faster than cats and tris with a maximum sailarea given?
     
  2. Doug Lord
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    Doug Lord Flight Ready

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    At this point it's tri's when you get over 20' with Hydroptere the fastest sailboat on the planet.
    Hydroptere and many of the fastest boats use hydrofoils to reduce drag . Most of the big round the world boats like Banque Populaire, Sodebo, Groupama are all trimarans using lifting foils in a manner called "foil assist" where a foil in the lee ama supports up to 70% of the boats weight(and is also retractable).
    In boats under 20'(or so) the 11' foiler Moth monofoiler is the fastest(in foiling conditions-current class top speed 30 knots+)-beating cats and all other monohulls including aussie 18's. The first time since I've been alive that a monohull is faster than multihulls even multihulls much larger like A-Cats, F18s.
    --
    The advantage of multihulls is their power to carry sail but a well known designer is working on a "thin mono canter" that he hopes will be the fastest ocean going boat period. He uses foils to increase the boats righting moment. ( http://www.boatdesign.net/forums/sailboats/monohull-speed-speed-dream-vlad-murnikov-30880.html ) The Open 60 monohull canting keelboats have recently started using dagerboards designed to give some degree of vertical lift like the ama foils on big tri's. The two leaders of the Barcelona world Race use such foils and are over 1000 miles ahead of the rest of the pack! This is an exciting time to be involved in fast sailboat design with spectacular new projects (and higher and higher speeds) happening all the time.


    PS: Note that Kites and windsurfers are faster than all these boats but are not defined as sailboats. There is always animated discussion about this but the USCG has come out with a definition explaining why a "sailboard" is not a sailboat......

    pictures: Banque Populaire, Hydroptere, Groupama, Foiler Moth, Speed Dream, Speed Dream 35' proto( click on image) :
     

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  3. jehardiman
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    jehardiman Senior Member

    As your question is formed, there is no answer. The question is too broad.

    What size is your "given sail area"? 1m^2?, 10m^2?, ,100m^2? 10,000m^2? Is a kite a "sail'?

    And what is "fastest"? 100m in a ditch? One way measured mile? Two way measured mile? Sea speed? Sea State requirements?

    Voyage capaible? Any variable load? Minimum or maximum displacement? Any personnel onboard? Cost performance?...etc, etc, etc...

    Too many variables. There is never one "best" hull design, only designs that better meet the design requirements.
     
  4. Brorsan
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    Brorsan Junior Member

    Um... I think you missunderstood my post completly.

    The question is not wich one is fastest overall. Let me give you an example: You got a 30 sqm upwind sailplan, you can shoose to put it on a cat, tri o canting mono. Wich one will be the fastest? You can have any dimensions on yur boat, but not 100% lifted by foild (foil assisted is ok)
    Kind regards
    /Brorsan
     
  5. Brorsan
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    Brorsan Junior Member

    Jehardiman, if we say 30sqm upwind, cost and dimension of boat is not an issue, 1 person onboard, an overall race with all wind directions and wind forces
     
  6. jehardiman
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    jehardiman Senior Member

    How long a race? If just "fastest" then a windsurfer or kitesurfer works to that criteria with less sail area (if you want 5 to 45 knts of wind). And foils can add speed to that (less efficient, but hey, delivered power is what you are after).
     
  7. gonzo
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    gonzo Senior Member

    If this is upwind, what is the angle? Are you asking about Velocity Made Good?
     
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  8. Fanie
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    Fanie Fanie

    I think you guys misunderstand what he's asking -

    Usually cat's and tri's are faster than mono's, so let's rule mono's out for now.

    The fastest boat per sail area would probably be the tri with cat's not far behind. But as you can see from the responses there are so many things to take into consideration - one simple one being the skipper of a vessel may fall far behing in a race if he's inexperienced even if he has the fastest boat under ideal conditions. Another is the bigger a boat the faster it usually is, so at what size would you stop. Another is the material used... and is it affordable. The variables are almost endless.

    You have to decide what it is you are after, then meet some design cryteria on the one side and what is practical on the other side. Nothing on boats are perfect and everything is a compromise one way or another. From there on it is personal preferences dictating what you can or cannot live without.
     
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  9. gonzo
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    gonzo Senior Member

    It depends on wind angle and sea conditions.
     
  10. Petros
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    Petros Senior Member

    Also it would depend on how heavy or light the wind. It is possible that in really light wind the mono-hull could be fastest. In heavy seas vs. calm seas with high winds might make a difference too. Same size sail, how long the hull? Displacement?

    I have noticed that over the recent years on long ocean going point to point records, that sometimes the conditions favor a tri and at others a cat. It is the luck of the draw I suspect on which configuration is optimum for the conditions during that particular record run.

    One local yacht wore that I sometimes crew on local races placed first and second in two recent races in a 26 foot sailboat despite much larger and more costly boats in the race. In light winds his small mono hull did very well.
     
  11. Brorsan
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    Brorsan Junior Member

    Actualy, i'm not looking for a specefic answer, i would just like to start a discussion. Sailboats are almost always compared leangthwise wich leads to very large sail areas on small vessels. I asked a friend the same question, he didnt counter questioned me with the specefic conditions, e said that the c-class multihul are all long slender cats.

    Compare a mono, a cat and a tri, all with the same sail area, you shoose the specefic number and condition, and give a proposal on which you think will be the overall fastest, or maybe "the tri will be faster upwind but will be beaten by the mono downwind" or something like that.
    Oh, and no windsurfers, no kiters, no superspecial that only work in very very specefic conditions like sail rocket, and no airborn boats, foil assisted is ok.

    I say it once more, i'm not looking for a one solution answer, i'm looking for a discussion.
    Thank you.

    (and I appologize for my bad english and description of the thread)
    /Brorsan
     
  12. Samnz
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    Samnz Senior Member

    Tri of course, there is no question. Take any rule I can think of and tris are fastest, F40, Orma 60 even C class till they banned them! Tris have higher righting moment for a lighter boat and tack better. they are faster than cats in light airs and heavy airs. Foil assist works better as its a wider platform
     
  13. Brorsan
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    Brorsan Junior Member

    Samnz, does that classes have free hull dimensions?
     
  14. gonzo
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    gonzo Senior Member

    If you think of the top speed at whatever angle of sail and not VMG, then a foiler.
     

  15. Brorsan
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    Brorsan Junior Member

    Gonzo, I think vmg is of more interest. Foiler = something airborne on foils? (if so, then of course, but lets talk hulls inw ater) :)
     
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