AC 36 Foiling Monohulls

Discussion in 'Sailboats' started by OzFred, Sep 13, 2017.

  1. Konstanty
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    Konstanty Junior Member

    With steps the foils is easier to tear off the hull from the water surface.
     
  2. TANSL
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    TANSL Senior Member

    I am not able to understand it. Could you give some technical reason to support this claim? Thank you.
     
  3. user63137

    user63137 Previous Member

    Thats is not true , the steps just work in planning condition. A boat can fly before planning. The steps in displacement and pre-plannig, generate more resistence.
    And I think that the canting keel is not safe in a match race. A lot of time to move the keel from side to other.
     
  4. TANSL
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    TANSL Senior Member

  5. OzFred
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    OzFred Senior Member

    Apparently the AC75 won't have a weighted keel, so no canting issues.:) Maybe there will be both daggerboards and foils, which will help greatly with upwind performance (and give the crew something to do).

    There are no dimensions on Agustín's diagram, so difficult to analyse beam. With the foils extending outward, the boat beam can be reduced maintain a similar "foil–base" to an AC72. They had a beam of 14m, so if you allow say 2m each side, the beam of a mono where the foils are mounted need only be 10m. Still very over–wide for a 23m boat, but less than an AC72.

    The IMOCA 60 class has no beam restriction, so they can go as wide as is practical. Safran's beam is 5.6m, Hugo Boss 5.8m. Scaled from 18m to 23m gives a beam of around 7.4m, add 2.5m and you have similar foil RM to an AC72 so really the AC75 doesn't need to be a rectangular scow.

    It's also informative to hear what sailors think of high–speed monos: the speed is amazing but the boats are very uncomfortable and noisy (which might be said of any offshore racer, but the IMOCA 60s more so). Perhaps tolerated for racing where speed is everything, but not for cruising. The Volvo boats seem to have a smoother motion, but still pretty extreme.
     
  6. Doug Lord
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    Doug Lord Flight Ready

  7. Dolfiman
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    Dolfiman Senior Member

  8. Doug Lord
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    Doug Lord Flight Ready

    The video:
     
  9. OzFred
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    OzFred Senior Member

    The foils must be made of solid titanium given:

    "… the use of twin canting T-foils, ballasted to provide righting-moment when sailing, and roll stability at low speed."

    Also, there's no indication of flaps on the foils, so how to achieve heave stability? Interesting times ahead…
     
  10. CT249
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    CT249 Senior Member

    How to bring together all the worst parts of a mono, a cat, a foiler and a canter, and do it in a way that annoys both mono fans AND multi fans.
     
  11. Dolfiman
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    Dolfiman Senior Member

    The cantilever arms of big fluctuant efforts are impressive, need not only extra structural resistance but also extra stiffness to keep control of the foils incidence angles and to have high enough frequency of the first eigenmodes of vibration to avoid excitation by the waves encounter frequencies or by vortexes ones. A major static and dynamic (hydroelastic) structural challenge with a very short time to design, build and validate it.
     
  12. OzFred
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    OzFred Senior Member

    The foils also provide the ballast. As a minimum I guess they must weigh perhaps 2 tonne each, so no mean feat to raise and lower quickly for manoeuvres. Perhaps solid titanium?
     
  13. Doug Lord
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    Doug Lord Flight Ready

    NZAC- I wonder if this render is an illustration of the TNZ intention to have one design boats OR is it but one possibility under a rule yet to be released?
     
  14. TANSL
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    TANSL Senior Member

    Whatever it is, it contains things that are worth thinking about and commenting on.
     

  15. David Cooper
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    David Cooper Senior Member

    It should attract a lot of interest from people who watch dangerous sports in the hope of seeing people killed - every time those boats are sailing side by side and the windward one wobbles it's going to have people jumping out of their seats with excitement.
     
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