35th Americas Cup: Foiling Multihulls!

What sort of maximum speed are they hitting? If you look at Groupama at about 4:50 into that video, it appears to be covering its length in half a second, which by my calculations would mean 67mph.

(15m x 2 x 60 x 60 /1000 x 0.621)

 

I think I read that the top speed so far is 47 knots........

 

All Round Foils( AKA "AP" or all-purpose foils)
Jack Griffin says all the teams have very light air boards "and what they call their AP(all purpose) boards". He recounts Oracle racing Team Japan in light air using their AP boards while TJ used their "light air" foils-he says Oracle won. Hmmmm, lets see: in preliminary racing Oracle used an allround set of foils to beat Japan which was using specialist light air foils! Something I've been saying is possible for months.......

listen about 52 min in-episode 36 Jack Griffin:

http://www.oceansailingpodcast.com/podcast

 

Practice Day Collision-
TNZ and BAR(Team UK) collided in prestart maneuvering. Minor collision nobody hurt but a little boat damage:
America's Cup on Twitter https://twitter.com/americascup/status/864610425517645824/video/1
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More on the hit: Will Damage Decide the America's Cup? >> Scuttlebutt Sailing News http://www.sailingscuttlebutt.com/2017/05/16/americas-cup-3/

 

Oracle Team USA-
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Bike power at the back of Team USA:

 

AC 35- Oracle Team USA
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Followup on previous post: Rumor is that Oracle is going all out on bikes-getting rid of grinders. There have been other rumors for weeks now that Oracle appeared to be low on hydraulic power.

 

TNZ with no jib--looking great: look at how long those foils are!

 

WOW! Watch the angle of attack of the outboard foil as she goes around the mark at the 2:00 minute mark.

 

Is it my bad eyesight, or the fact that they are down low pedaling? ....in the first portion of that video it appears as though the 'power guys' are not having to put out 100% ??

Are they generating enough hydraulic power that they are able to take some 'breathers' in between?

 

Given that you can produce about 4 times the power with your legs as with your arms, then they should easily have spare capacity compared to the hand crank teams. Even though the total energy available is nominally similar (it isn't, for various reasons, but is assumed to be), with several cyclist, they can pause to recover in sequence and still maintain a higher mean output.

 

hump, I'm curious why, if what you say is accurate, all the other Teams didn't choose leg power? Are there disadvantages compared to "normal" grinders?

 

There are advantages and disadvantages to both methods, it is not entirely clear cut and depends on each application. The footprint of the cycling posts are greater, so if space is limited this is an issue. The setup from each transition is a little longer, so in a tacking duel it could be slower. For sustained energy output the limit is usually heart and lungs, so neither method has an advantage.

However, for this application, where short burst of high power can keep the boat foiling, the cycling has to offer an advantage as the net gain will continue to be felt down the course after the power delivery has reduced, and it is not clear to me why all the teams did not choose this method, given that the French have proven its effectiveness years ago (Cammas used it on his tri in the RdR maybe 8 years ago, I forget now). Note how steady in pitch ETNZ are in transitions and roundings compared to the competition, this is due to the ability to provide very high power for the short period of the transition.

The benefit increases when the total crew mass is restricted, so you can't have the ideal grinding physique using hand cranks as this would be a 115-120kg person, where as the ideal sprint cycling power physique is closer to 90-95kg, as leg muscle development is more easily isolated.

I'm curious too, and hope we get more information about the design choices after the cup is over.

 

Thanks-I hope we find out more as time goes by-after we get the lowdown on the "all purpose foils".....

 

AC 35-Opening Press Conference Live 11AM Thursday, 5/25/17 :

 

Artemis-Foiling Tack: click on the link. if you get the sign up window and you don't want to sign up, click "not now" , then click on the two diagonal arrows in the lower right corner and you'll get fantastic video.
Artemis Racing https://www.facebook.com/ArtemisRacing/videos/1754575417902217/