34th America's Cup: multihulls!

34th AC

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You biased-nooooooo! But you deserve to be . TNZ has continued a long tradition of innovation, inventing a whole new way to foil for this America's Cup and thereby providing small cats a new way to go faster-TNZ has been almost solely responsible for the trickle down in foil systems to the LAC and to a number of catamaran manufacturers. Regale yourself in this proud tradition now because the 17ers are about to crush the little Kiwi bird with spectacular sailing and foiling upwind!*
*That is, if they're not thrown out of the whole regatta for cheating.......

 

You would never diss monohulls, Doug, because they are all potential foilers

And that loss of breath was just you getting a touch of the vapours at the
thought of the NZ Oracle race.

 

The Americas Cup

The America's Cup: http://www.youtube.com/watch?v=X7gFhsnlpXE#at=27

 

Doug;
If Oracle does indeed foil upwind, wont it's VMG go out the window ?
I would of thought sitting up on foils to windward she will go very fast......sideways !

 

34th AC

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See, thats what everyone thinks. Oracle is hiding the most significant breakthru in foiling since TNZ invented these foils in plain sight!
So she is photographed sliding sideways upwind and Kiwis think she can't foil upwind-devious and crafty, ain't it?

 

And just when people are starting to suspect that they can do it, they leak the cheating scandal to divert attention from the boat. Very clever indeed!



R

 

34th AC

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Obfuscation: all's fair in love and...the America's Cup.

 

John Navas had video of the Arab/Kiwi foiling to windward taken a few weeks ago. Don't think this revelation is very revolutionary anymore.

 

That was with BRC (before rule change) foils. I'll wager you have no photos of them doing it after the safe foils were installed.

 

Sorry Randy, I shouldn't have used the Arab/Kiwi (smart arse, caused confusion) term, which really means ETNZ ... a design that has always had pure-as-the-driven-snow legal foils and rudders.
It's that boat originating from the evil empire of cheats that has had to change rudders.
But the Navas video DOES show ETNZ foiling/flying to windward at tremendous speed; just don't know how close to the wind they were sailing. Maybe in old terms, full and bye.

 

Hi Doug,
Please stay in your place and don't expand too much. Conspiracy theories are my prerogative, remember that?


Jokes aside, if any of these crafts start foiling both upwind and downwind, the other competing side will at that point be entitled to call it a breach of rules.

This thread is moving at a very fast pace, so many posts have been written and then got lost in the sea of other incoming posts. Let me remind you of this exchange of opinions about legality of foiling which I have had with Tom Speer some time ago, here:

Daiquiri, post #1850:

"Back in my post #1751 (34th America's Cup: multihulls!) I have asked how did they arrive to use daggerboards for foiling, given that AC class rule defines daggerboards in this way:

AC72 Class Rule, Section 1, item 1.4.e:
"daggerboard means a retractable appendage primarily used to affect leeway. The term daggerboard is synonymous with bilge board, centerboard, lifting keel and sliding keel"​

Doug has replied to this saying that what is not explicitly prohibited is to be considered allowed. But I am seeing the 1.4.e as an explicit prohibition of using daggerboards for purposes which are more important than leeway control.

Now, as you said, currently daggerboards carry approx. 6 t of vertical load, which is twice the amount of horizontal load. The way I read these numbers, it means that daggerboards are no more primarily used for leeway control. The whole design philosophy of these boats is currently centered on the foiling capability, which is so important for the victory that all boats are currently flying on foils (which are - daggerboards).

Of course, daggerboards are still necessary for the control of leeway - but is it still their primary function or can we say that the leeway control currently has at least the same level of importance as the generation of vertical lift? Everything in their design reflects this other primary purpose - their shape, their usage, their structural design - in which case, the item 1.4.e of the Class Rule is violated."​

Tom Speer's reply, post #1876:

"With all the attention on flying, people are forgetting that there's roughly equal time spent sailing upwind with a hull in the water, compared to sailing off the wind with the hulls free of the water. The daggerboards provide leeway resistance 100% of the time. Flying, while spectacular, really is a secondary function of the daggerboard. A boat can race without flying (although it may not be competitive in the current environment), but it can't do without the leeway function. So I think it's still fair to say the primary function of the daggerboards is to provide leeway resistance.

There's still a lot of drag associated with the side force due to leeway, and a great deal of the daggerboard design is concerned with minimizing that drag. It drives how the boards are operated, such as what cant angles are best for upwind vs downwind, how much immersion the boards should have, etc.

I don't think flying violates the Design Rule. I think 1.4.e is more descriptive than proscriptive. I think the daggerboards were intended from the start to provide some vertical force. Flying is a difference in degree rather than a difference in kind."​

In other words, Tom has argued that boats are not in breach because they are not foiling both upwind and downwind. So the daggerboard is still (on average over the course) primarily used for controlling the leeway.

But... If any of the competitors started foiling upwind as well as downwind the "average over the course" argument would be no more valid - the daggerboard's "average" primary function would be no more the control of the leeway but the continuous creation of the vertical lifting force (which is already numerically predominant). And, should it reveal itself as fundamental for the victory, then the vertical lift generation could be no more called the "secondary function" of the daggerboard. Hence, a breach of the Class Rule. Hence, more job for the lawyers.

 

Well It wouldn't be an AC regatta without legals at 20 paces now would it !

 

An excellent result then, especially when the lawyers know the clients have
stacks of money and are unable to sort the problem out themselves.

 

34th AC

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Slavi, I don't think thats what Tom was saying at all. Whether the boat is sailing upwind or offwind the daggerboard will always be developing lateral resistance. This ,to me, is the operative Tom quote:

Flying, while spectacular, really is a secondary function of the daggerboard. A boat can race without flying (although it may not be competitive in the current environment), but it can't do without the leeway function. So I think it's still fair to say the primary function of the daggerboards is to provide leeway resistance.

 

But the daggerfoil has not ceased to be concerned with controlling leeway at any time.

Statistically speaking, you simply need to do some pre-start Archemedian maneuvers on your hulls with your foils down and you are still in the clear.

The function of the foils is not binary, it is not either or, it is leeway control or both leeway control and lift fraction simultaneously.

The foils ALWAYS control leeway, they periodically provide lift fraction. Even if you sail upwind on foils, they still always provide leeway control, in fact leeway control is a pre-condition of flight so you always need leeway control to even contemplate flight, thus, leeway control is present more than flight is, always, thus daggerfoils, are always daggerfoils and it is almost impossible to be in contravention of that rule