Foil AC pics and vid

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ifoxwell

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Where are they all?
Now that its launched and in the Solent (not the most remote stretch of water) i cant believe there are testing it with no watching?
Ian
 
I'm not sure how long this has been around, NZ labelled as tacking, and although it's actually it's gybing I'm still quite impressed that it's coming together.

 
Thanks, interesting although not as interesting as listening to Alex Thompson walk as around his boat immediately after
 
anoccasionalyachtsman said:
I'm not sure how long this has been around, NZ labelled as tacking, and although it's actually it's gybing I'm still quite impressed that it's coming together.
Click to expand...

Interesting question. It was clearly a turn away from the side the sails were on. But if going “downwind” faster than the wind speed, so the wind is coming from ahead the whole time, is it ever a gybe or is it always a tack as the wind never goes behind the beam?
Our old terminology derived from previous centuries may not easily equate to the mind bending properties of superfast modern foilers.
 
dunedin said:
Interesting question. It was clearly a turn away from the side the sails were on. But if going “downwind” faster than the wind speed, so the wind is coming from ahead the whole time, is it ever a gybe or is it always a tack as the wind never goes behind the beam?
Our old terminology derived from previous centuries may not easily equate to the mind bending properties of superfast modern foilers.
Click to expand...
However it feels on the boat, probably best to stick with the term just for the crew's sake!
 
its a long time since I've read Frank Bethwaites high performance sailing but doesn't he say in that book something like, you only ever sail upwind in a performance boat. I know at the time, in my Firefly, I struggled to get a handle on that concept but having now sailing dingies like 49ers, Musto skiffs, 800's etc it all makes much more sense.

Good to see Britannia on the water... although it would be nice to see more of what it's capable of. Clearly They wont want to show the world everything but there must be others around on the water with a phone that could record something :-)
 
How do AC 75's work? They appear to defy every single rule that was drummed into me over 50 years ago. Seemingly with no ballast and no keel for lateral resistance they should either skid around uncontrollably or they should fall over. Instead they seem to pick themselves up and fly. Could someone explain this, in relatively simple terms, to a confused old 'un?
 
Ballast wise, each of the two main foils weighs 1,215 Kg which helps the fairly high form stability at low speed, but by supporting the boat on a leeward foil - which has a centre of lift about as far out as a trimaran's lee hull would be - then most of the boat's weight is opposing the heeling force.

The lateral resistance comes from the vertical part of the foil, and at these speeds it doesn't need a lot of foil to do the job.
 
Oh, and... they do.

AC75Crash.00-960x530.jpg
 
There is some video of the capsize. Bows went high and foil shot out of the water completely, whereupon there was suddenly zero lift and gravity sent back down with a bang and slowed right down, causing an eventually gentle slow speed capsize.
Apparently sailing again later the same day. Very lucky to get away with no damage, to crew and boat
 
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