http://catsailingnews.blogspot.com.au/2012/02/ac45s-ahpc-airborne-lfoils.html

Interesting. Allowed in the rules or not?

Still not lifting the boat out like a moth. But they say 25 knots in 20 knots of breeze. But are they sustaining those types of speeds for long periods of time or just spikes?

My standard Viper gets 10 sec averages over 20 kts so maybe it can.

I heard a rumour that these things will fit the old boats as well. You dont need to lift outof the water like a moth when you have as much power as an F16.

I wonder if there will be any more surprises before the trials.

And the next big new thing will be T foils on rudders to maintain the front foils AOA, making the boat feel like an 18fter.

Followed by variable AOA on the front so it doesn't hobby horse downwind. Can't imagine hobby horsing downwind is fast, but looks good for about 20secs.

I imagine a standard curved foil will stay in place just fine but what about these?
Are they locked or lashed in place somehow?

F16 Rule 1.6.4 says its prohibited...

It's not the shoal draft option?

OK...so how did they get the L boards down into the hulls? Can they be slid up from underneath?

Hobie figured out how to 'foil' a long time ago, yet it never really caught on as a racing class.

Can any of you older guys who were active 'back in the day' of the Hobie Tri Foiler shed some light on some of the issues? I remember seeing a fleet of them, once, at the Wildcat regatta, but they looked like a real pita to put in the water, and weeds on the foils were always a problem.

http://www.youtube.com/watch?v=zXSgZCDVWOM

Stick with it, at about 2:37 it shows some of the design concept and the L foils, and how the ski at the front adjusts the up/down lift. It also shows Russel Long going 43 knots in his "Long Shot" during a speed run in France, in the ditch and a two up regular version going 35knots at the end. But I notice all the video speed shots are done with good wind...on FLAT WATER. Great for a lake.

I'd love to have one here on my lake, but I'm not convinced a 'lifting' foil, if C boards or L boards, is going to be fast on lumpy water, in the kind of racing we do in the ocean or lage bay. All that porpoising up and down can't be fast. You may get a small burst of speed when you come up, but when you nose dive back down, it could get ugly. They'd have to come up with a device to controld the AOA to yeild a steady ride over rough seas.

Anyone know where Gregg Ketterman is today? I wonder what he's up to, design wise.

I'm sure you will see these at the Olympic trials.

Timbo,
Thats probably want they did, guessing here, but that isn't allowed in the F16 rules either. You have to be able to lift the board up out of the well. Again, F16 rule.

Mike

Would a board with a hinged tip be illegal? If you made the tip asymetric with a hing it could be pulled up the well and the shape would push the tip to the correct possition when under speed.

Yes, that is illegal. According to F16 rules: "End fences/horizontal appendages below the waterline will not be allowed."

In my opinion not allowed under current F16 rules:






I dont see any interpretation that will allow for this on daggerboards. On rudders I read this in such a way that fences are allowed (like used on the Stealth).

Will be interesting to see if they send a boat with these daggers to the olympic trials. I dont know about any substantial two boat testing with this technology where the results are public.

I think it's safe to say that the f16 rules weren't a consideration when coming up with this new development. The Olympic trials are the aim.

As for the foils I had a conversation with Greg about curved foils and the like. He said that someone has done some serious work for them on this topic, and the conclusion was curved foils are quite draggy, and that straight assymetric boards is where the effort should be directed.

Oracle are also testing the same thing. I think we can draw our own conclusions from this.

WHAT IF....

Put the dagger slot in the hull at a 45 degree angle, so you'd have a long, straight dagger board, but on a 45 degree angle, which would provide some amount of lift, perhaps even more than a C board...yes? And you'd be within the rules, yes?

Has that been tried yet?

seven degrees max angle on boards

Ahh...well, we could change the rules. I think I'd rather have straight boards at a 45, than have to deal with C, or L boards, and I think that would provide more lift too.

except if you pull the board out and clip the boat next to you...

Agreed. Whatever the angle, I can't imagine that moving curved boards back and forth is as easy as straight boards (not to mention the obstruction when they are up).

I'm very curious to see how well the AC crew handles curved dagger boards on the AC72s.

I wonder if a removable T(orY) foil extending off the dolphin striker would provided enough lift or practical/doable?

That would be absolutely doable and thanks for that idea. I might steal it from you.