Wings, the Next Generation
Wanna have some fun? Set Paul Cayard loose on the subject of America's Cup 34, some re-imagined and surprising wing-control mechanisms, and the terrors of San Francisco Bay in full cry. The custom AC72 catamarans of 2013, he says, will be 30 percent more powerful but 'much less stable' than the AC45s that sailed three events this year on the America's Cup World Series circuit.
And occasionally failed to maintain verticality.
Cayard's home waters, where the Cup will be sailed, are known to be a windy spot, and when the ebb tide works against the seabreeze—one sixth of all the water in San Francisco Bay goes out, and in, twice a day—then she be lumpy, mon. Sea state, even more than wind strength, is something to fear once the breeze is up, funneling through the Golden Gate and peaking on many days at 18-22 knots. Unless it peaks at 30, and shucks, that's just home for the home folks. But what does it mean to racing an AC72 with 38 hydraulic cylinders in the wing?
Until the first AC72s are launched in July, 2012, it's all theory, but, 'If you're making 25 knots upwind and 40 knots downwind, tacking on someone and gassing them just isn't happening,' Cayard says. 'In seriously-overpowered boats, the match will be about who can actually get the boat around the course and figure out how to avoid that extra gybe that costs you maybe 20 seconds, maybe 250 meters.'
As CEO of the Swedish challenger, Artemis Racing, Cayard is not shy about telling you that his Challenger of Record team has gone its own course in engineering an AC72 wing. The box rule governing the AC72 is one big sandbox, so the engineers get to play.
Oracle Racing Team Coordinator Ian Burns explains: 'I was involved in writing the rule for the AC72s, and when we addressed the wing, we started with a complicated rule, to limit what a designer could do. We added more and more pieces as we thought of more and more outcomes, and we came to a point where it was so complicated—and it was still going to be hard to control, because the more rules you write the more loopholes you create – that we reverted to a simple principle. Limit the area very accurately, and make it a game of efficiency.'
The Artemis approach to efficiency, Cayard says, uses a three-element wing. No surprise. Any wing is much more efficient than a mast and soft sail—for many reasons, not the least of which is that mid-leech tension becomes a non-issue—and C Class catamarans long ago demonstrated that three elements, two slots, are faster than two elements, one slot. I expect every AC72 to have a three-element wing.
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