AC 36 Foiling Monohulls

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

  1. gggGuest
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    gggGuest ...

    And a very old one. In one of his 1930s books Uffa Fox rails (in very un PC language) about J class rigs that fall down in a strong breeze.
     
  2. Dolfiman
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    Dolfiman Senior Member

  3. CT249
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    CT249 Senior Member

    So you gain a couple of % of speed, maybe, at the cost of a lot of complexity. And if you are in a marina berth you can't move from the cockpit to the bow without crawling over or ducking under foils- and coming alongside you have to work out some complex fendering system.

    Meanwhile in the real world, lots of people have dumped their big genoas and moved to short overlaps to lose 2% of speed but gain economy and handling. In terms of overall speed they'd be just as well off pulling their old #1 headsails out of the shed, and it would be much less cost and hassle.
     
  4. CT249
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    CT249 Senior Member

    Yes, I'll have to check whether that was before they introduced the new rules to make rigs dramatically stronger and heavier, and require full accommodation, to ensure that AC boats had a useful life rather than being bleeding-edge race machines as is so often claimed.
     
  5. Doug Lord
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    Doug Lord Flight Ready

    Watching the Superfoiler videos it's interesting to note the frequency with which the main hull touches down. The overall beam divided by length of the SuperFoiler and the AC 75 are very close measured from approx cl of main foil to cl of main foil-around 55%. Looking at the renders TNZ put out they (of course) don't show the main hull touching down while sailing. But in the real world I'm thinking it surely will.
    The Super Foilers are one-design so everybody has the same problem with the mainhull touching but with the AC 75's that probably won't be the case. We'll know more when the rule is released at the end of March. If there is any substantial design leeway then finding a way to keep the mainhull clear may pay substantial dividends....

    SuperFoiler:


    Heavy air Gold Coast:
     
    Last edited: Feb 18, 2018
  6. Dolfiman
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    Dolfiman Senior Member

    Yes, and moreover on open sea with real waves, in this video we are in sheltered flat sea. AC rulers, up to now, are not very clear on the maximum sea state (not to mention maximum wind speed) for their regattas. It's important for the designers as for the pinnacle dimension of an AC regatta.
     
  7. Doug Lord
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    Doug Lord Flight Ready

    I'm thinking about a boat like NZAC using Welbourn foils or even the TNZ renders but with the ballast removed from the foils and put at the bottom of a canting keel* using a version of the K Foil where the foil at the bulb can be used or retracted. This would allow lift from the K Foil to keep the hull flying in marginal conditions and when not beneficial it could be retracted.
    *maybe only 25 degrees or so each side


    I called this the "K Foil" over 20 years ago when I came up with it and patented it May 3rd 2005, Patent Number 6,886,481 B1 . I think it has potential to be refined and be beneficial on a foiling AC boat/monofoiler:
    kfoil1.jpg kfoil2.jpg
     
    Last edited: Feb 17, 2018
  8. OzFred
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    OzFred Senior Member

    Wind and wave limits will likely be published well ahead of the event and be fine tuned based on lead up events.

    AC boats have not been true ocean racing yachts for a very long time, the America's Cup has never been an ocean race, though it might have been raced in the ocean. I imagine the rule about boats having to reach the venue on their own bottoms (i.e. having to sail there) was introduced to benefit the defender, which could be built very much lighter for smooth or sheltered waters than a challenger that had to safely cross an ocean to reach the venue.
     
  9. Doug Lord
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    Doug Lord Flight Ready

    Remember 1987-roughest water of any modern Cup.......
     
  10. Konstanty
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    Konstanty Junior Member

    We can return to the regatta around any island at wind from 2B to 8B. Yachts are too small when we can bring them there.
     
    Last edited: Feb 18, 2018
  11. Dolfiman
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    It is that the concern about wind limits is more acute for the AC75 concept than for good old 12 m JI that had (still have) a large spectrum of use. Remember the brillant career of American Eagle once refitted for IOR races :
    http://sparkmanstephens.com/12-meter-american-eagle-market/

    One can regret that such potential is no longer envisaged but the fact is that the proposed AC75 concept will have a narrower spectrum and that regattas will be under the threats of two extremes : too light winds, too strong winds.
    Too light winds to take off and/or to maintain a full flying mode : 8 or 9 knots this limit ?

    Too strong winds to keep control of the boat : 20 knots ?

    Let'say consider a weather window of 2 hours, from leaving the quay to the end of a 40 mn race, that's leave room for variable wind forces, with probability of gusts over 20 or of drops under 8-9. It is not as such a fatal drawback but that reduce the number of sites/periods and should not facilitate the planning of shows with TV coverage on a daily basis programme.
    As an example, the start of the Jacques Vabre 2015, 1h30 of TV coverage without wind, hard for the commentators !
     
  12. OzFred
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    OzFred Senior Member

    I think you need to realise that sailing has moved on, that people don't want to watch races that take hours, with boats drifting along in zephyrs. The market now (and for quite some time) is for much shorter races at higher speeds, exemplified by 18 foot skiffs. Unfortunately, while the boats themselves were great to watch, I think viewers had no emotional connection to craft representing business sponsors rather than geographical regions or countries.* I think the SuperFoilers have a similar issue: everyone marvels at the skill of the crews in racing them, but there's no emotional buy–in in the same way people follow other sports. But that's a topic for another thread…

    Has any AC boat since the 12 Metre era gone on to have a successful post–AC career in any form of racing?

    * I think the ongoing concept of AC entrants representing countries (yes, I know they actually represent clubs, but that's not how it's presented) is about the only thing that keeps "the masses" interested. Take out the country name and you have Oracle vs Emirates. Even Land Rover BAR raced with a huge Union Jack on the sail and promoted themselves as "the British America’s Cup Challenger", so while not British in name, they presented as representing the UK or Britain (clever too that the Indian sponsor, Tata, used a UK brand that they own rather than their company name in the branding: Tata BAR may not have been so popular ;-) ).
     
  13. CT249
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    CT249 Senior Member

    When the Deed was altered to require boats to be sailed to the venue, it was said to specifically be to ensure that the boats were real dual-purpose craft. The Americans thought that since the schooner America had sailed to the venue and had beaten the British offshore-capable boats, it was only fair to expect the same in return. George Schuyler, the only donor of the Cup who survived to that date, said that if the Cup was not sailed in ocean-going boats than it was not worth racing for it. The other people involved in redrafting the Deed (IIRC) said that they didn't want something like a giant scow or inshore catboat to win the Cup.

    It's commonly said that the rule was intended to benefit the defender, but arguably it's better to take the words of Schuyler and his co-drafters at their full value since the Americans did change the Cup classes on several occasions to make them into offshore style boats that were representative of normal club or regatta racers. For instance, the dropping of the Seawanhaka rule boats like Reliance and their replacement with the Universal Rule; the changed to make the boats built to Lloyds hull rules; the alteration of the J Class rules to require full interiors and heavy masts. These changes all killed off potential defenders so they indicate that the NYYC was serious about trying to keep fragile inshore machines out of the Cup. They did the same thing when they banned open cockpits from the 12s.

    Arguably it was the Kiwi "big boat" challenge and the shift to the IACC class that really killed off the Cup that the donors had wanted to see. The last few Cups taken it even further.
     
  14. CT249
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    CT249 Senior Member

    With respect, Fred, televised sports like Tour de France stages, F1 races, tennis and golf still seem to go on pretty long. The TV stadium sailing events all seem to be struggling to attract big audiences. I'm not sure about the reality but there was a recent claim that the match racing tour is in trouble now it's in foiling cats.

    Pretty much the first part of the sport to go to the televised short-event stadium sailing model was windsurfing, which soon afterwards suffering a huge drop in support. The biggest companies in the sport are currently going back to their roots since the high-speed model failed. I did a fair bit of the televised pro circuit stuff and it just didn't work as it should have, since reliable wind is so hard to find even when you schedule the event in the windiest time of the year.

    You could of course still have a class that does short races and has a wide wind range and is seaworthy.
     

  15. OzFred
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    OzFred Senior Member

    I stand corrected on the "own bottoms" part.

    I don't want to get distracted by a debate on participation.

    In regard to faster, more specialised boats on shorter courses, you only need look at cricket to see how the shorter forms of the game have influenced the longer forms (for the better in my opinion) and how techniques and tactics have changed dramatically as a result.

    Sailing is undergoing a similar transformation: faster boats mean traditional match racing tactics have to adapt and develop new options. For me, the biggest issue for the AC is a match race between unequal boats. It's almost certain to happen in a development class and leads to one boat being clearly faster than the other, resulting in boring racing relieved only by the spectacle of the boats themselves.
     
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