35th Americas Cup: Foiling Multihulls!

Discussion in 'Multihulls' started by Doug Lord, Sep 26, 2013.

  1. Doug Lord
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    Doug Lord Flight Ready

    So lets begin the discussion of what could be next and follow what Larry tells us will be next. For the the time being lets speculate on the boat, the course, the venue ,the technology. Then as things develop lets discuss the developments.
    For this thread lets let AC 34 be history........

    UPDATE 9/30/13: Australias Hamilton Island Yacht Club confirmed as Challenger of Record.

    Bob Oately the owner of the fantastic "Wild Oats XI" is behind the challenge.
    Last edited: Sep 30, 2013
  2. Doug Lord
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    Doug Lord Flight Ready

    35th AC-The Second Foiling America's Cup

    Does anybody think that a trimaran should be considered or should Larry stick with the 72's?
    I don't think there is any doubt about sticking with hydrofoils, but maybe we'll
    have to ditch the wing and go with modern reefable soft sails to enable the end of ,at least, upper wind limits?
    I hope the guys decide to stay in San Fran-it was just spectacular and the wind was extraordinarily reliable.
    What do you guys think?
  3. Stephen Ditmore
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    Stephen Ditmore Senior Member

    I'm for foiling, but with less restrictive rules. Perhaps anything that will fit inside a 90' radius sphere (or something like that). The one area where I'd like to see more restrictive rules is strength/scantlings. But with respect to tri vs. cat and other configuration questions let the designers decide and resolve disputes on the water!
  4. xarax

    xarax Previous Member

    The role of the wing in the case of foilers has been overestimated - the difference in speed and angle between a wing and a carefully designed wing mast / reefable soft sail combination would be insignificant.

    I would like to mention another issue that has been overlooked : Personally, I believe that the upwind legs are as demanding and significant ( if not more ...) than the downwind ones - so I would like to see a course with, say, two upwind and two downwind legs.
  5. MoeJoe
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    MoeJoe Junior Member

    I think that sponsors prefer a world-wide audience with multiple nations participating. And that may drive the rules for the next set of rules to something a bit smaller and a fair bit cheaper. I think that foiling catamarans driven by kites would be pretty cool. Should be possible to get very fast boats with that setup. No electronic/computer assist for handling the boats. And crews which are strictly national would help the patriot aspect among supporters. San Fransisco was a great venue but a change to another place is still better I think, a fresh backdrop.
  6. Doug Lord
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    Doug Lord Flight Ready

    2nd Foiling AC

    Thats a great idea-I agree completely!
  7. salglesser
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    salglesser Junior Member

    Great thread Doug, thanx.

    I would like to see more development in soft wings.

  8. champ0815
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    champ0815 Senior Member

    Well, if this is a wishlist:
    - Only wind limits: if a race is started, the first to get to the finish line is the winner, no matter how long it takes.
    - Longer races: AC34 races in decent wind conditions were over before they begun - most races were decided right on the start line or shortly after, since the time to make errors or to improve was to short. Since it was such a good TV show, maybe something like a course with as many legs as fit into one hour of racing or so should be calculated without the risk of loosing to many viewers.
    - as for the technical side: no electric actuators, just human power and reaction times to make best use of the wind, everything else should be mechanics and to fit within a box rule.
    - seaworthy boats: they have to be able to perform safely in a variety of (wind) conditions, the responsibility for safe sailing should come down to the teams to make the right decisions about sail area and the right angle to the wind and not to the organising committee.
  9. markdrela
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    markdrela Senior Member

    Whoa. How did you reach that conclusion? Once you remove the hull from the water, the upwind VMG is mostly determined by the L/D of the "airframe", much like with a land yacht or ice boat. A soft sail with stay cables is not going to beat the L/D of a cantilever rigid wing.

    If you try to make an unstayed soft sail, then the mast will have to have a thickness similar to that of the wing. To make it aerodynamic it will then also have to have a similar chord, in which case the soft part of the sail rig becomes pointless.

    And a soft sail will almost surely need much larger control loads than a wing, but that's a whole other topic.
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  10. Corley
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    Corley epoxy coated

    A longer course would be welcome I'd like to see the restrictions on design eased somewhat I'd love to see a foiling AC72 trimaran or some sort of super proa as well as the catamarans? Lots of interesting platform options that could be explored. I'm not convinced on the cost angle or that they should be contained it is the America's Cup let the teams spend. I hope the AC45's are retained as a feeder series maybe they should make them foiling now since the retrofit doesn't seem that onerous.
  11. Doug Lord
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    Doug Lord Flight Ready

    I can see drawbacks on larger versions of this but the Moth foiler uses a stayed rig and "soft sail"-on a 32 knot + boat. I wonder if materials science has come far enough that a larger version would be possible? Morrelli and melvin have spoken on this but I don't have the link handy, but the control loads will be a big deal unless some innovative guys solve that.
    Wings have not worked out so far in the A Class where Ben Hall tried one, and in the Moth Class(this may be due to rule restrictions).
  12. xarax

    xarax Previous Member

    Elementary, my dear markdrela...:). Calculating the percentages of the differences in the boat speeds those two things ( the wings and the foils ) were able to offer. Reading what Gino Morelli, who wrote the AC72 rules, had said, helps, too :


    GM: I think the excitement that has been generated in this Cup has way more to do with foiling and flying than the wing. If we used the same platform with soft rigs and rotating masts with fully battened sails, then first you can reef them, second you can launch them at your leisure like a normal boat, and third you eliminate the wing-building team and the problem with the handling of the wing, the hydraulics, and control systems. In reality the difference between the performance of the boats with a wing on foils and without the wing on foils, won't be much. They’ll still sail at 40-plus knots. Maybe they don’t sail at 165 degrees downwind, but at 163 to 160, and they’ll probably still fly in as little wind.

    Does Hydroptère use a wing ? Noope...
  13. sharpii2
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    sharpii2 Senior Member

    I agree with losing the silly wing sails.

    The second thing I'd get rid of is the upper weight limit.

    I would also like to see a lot less restrictive design rules.

    It has occurred to me that a non foiler might be faster around the course, even though it may have a far lower top speed.

    The 15 kt course averages give me this suspicion.

    Wouldn't it be cool to see if foiling at this scale is actually faster than non foiling?

    Due to the 34th cup design rules, we were not allowed to find out.

    I feel cheated.

    A big part of the original AC race was to determine if the fine American bow was better than the full British one, so such a contest would have deep traditional roots.

    A heavier boat would not foil, or at least not foil as fast, but might have an advantage on the upwind leg, where it must bash against the bay chop.

    I have no quarrel with allowing wing sails.

    What I objected to was mandating them.

    Such silliness also has deep traditional roots in the AC.

    But really. Shouldn't we be trying to root that out?

    I would like to see a rule that mandated:

    1.) Max Sail Area upwind,
    2.) Max Sail Area downwind,
    3.) Minimum total weight, and
    4.) Some trade off allowance, such as Length vs. rig height.

    There could be a list of stipulations following this, that forbid really whacked out technologies, such as some of those forbidden by the AC72 rules, followed by another, mandating certain safety features, such as flotation compartments.

    I would also like to see a capsize* equals sink rule, so well funded teams end up with similar risks as poorer teams (who don't have a spare boat on hand).

    *Capsize being any knock down the boat cannot recover on its own from.

    I hate like hell getting the impression that this is a contest where he who has the biggest wallet can comfortably be predicted to win.
  14. redreuben
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    redreuben redreuben

    Agree, lose the wing and develop this idea.


    At least the tech can feed back to ordinary sailors, I also agree about the upwind legs, gotta be two, I thought the races were too short given the speeds we are looking at now.
    I agree with manual systems only but I reckon foils should be open slather.
    Whilst I'm not a fan of Nationalism I can see how a crew rule would benefit popularity perhaps somewhere in the 50 -80 % range ?
    That'll do me for now !

  15. redreuben
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    redreuben redreuben

    Forgot one.

    Free beer !
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