AC72 Oracle Team USA Spaceship has landed

Those bows look very skinny/low volume compared to the rest of the boat/rig. I wonder if that's why they added the T foils to the rudders. to keep it from going bow-down, or....are they going to try to foil it?

If they can keep the L boards from snapping, I could see where they might be able to foil, but I don't see any means of adjusting the ride height if they do get it up in the air, and they were obviously sailing it on one hull only, so I don't think the intent is to foil it, unless they are going to work their way up to that, after they get used to sailing it.

i cant remember were i read it but the t foils are there is its less likely to pichpole

Cant wait to see these cats race:

I noticed that too. A 72 foot boat with a tiller... I wonder if they are going to keep with that or if it was just something for testing. I noticed that New Zealand's boat was wheels.

Close up of the team installing the tiller arms.

The rules prohibit any underwater adjustment of the foils (flaps, etc.)...but they do have the ability to hydraulically tilt the daggerboards fore and aft quite a bit. The hydraulic power comes from the manual winching stations.

It's a strange tiller too - they can steer the boat while standing up by swinging the rod/bar from side to side. I hope he has something else to hang on to...I have visions of those capsizes where you slide down the trampoline with the tiller in your hand...which makes the rudders turn more into the flip.

Yeah, if they are going 40 knots, I HOPE the driver has a seatbelt! Otherwise it's going to get pretty sporty every time they stuff a bow! I wonder if they'll have a single driving station in the center, with a seat and belt, so the skipper doesn't have to run the full width of the boat with every tack/gybe.

The exact same system has been used on Dutch merchant ships since the 1600s.
There are extensions going to each side so he can steer from both hulls though, no need to stand on the center platform.

The steering action is the exact reverse of a normal tiller though, I wonder if they changed that somehow.

Don't count on it. They're going to optimize every ounce of righting moment.

Article - NZ foiling on Waitemata Harbour

Wow! How Cool is that!

I guess they will indeed be foiling in the AC races, that should liven it up a bit! I can't wait to hear what the Lead Bottom Leaning Society at SA will have to say about this!

Can't wait to see just how fast these things will be!

It will be interesting to see how they manage foiling around the course. I wonder if they can foil effectively upwind at high angles.

Well, if they do crash, at those speeds, it should be spectacular!

Many years ago when we were having a discussion here about how to get more mainstream TV coverage for sailboat racing, I said we needed to make it more like NASCAR, with faster speeds and more 'crashes'. I guess they finally have!

http://www.youtube.com/watch?v=eeLacBmYxyU&feature=fvsr

People love to watch expensive stuff crashing at high speed.

How much drag would the windward L foil generate in low winds? (not so probable in SF Bay)

rules do not allow use of the windward foil, I do remember reading something about exceptions (rule 47.3)

they didn't want to get into situations where the windward foil was used to pull the boat down for more righting moment...so they disallowed it's use.

Looks like it foils pretty well on 3 legs though.

Here is the skinny on rule 47.3:

47.3 Preventing windward daggerboard increasing righting moment
After starting, an AC72 yacht shall have the windward board draft stripe(s) visible so to
confirm that the board is no more than 0.500 m below MWP, unless one of the following
applies:
(a) the windward board does not penetrate the surface of the water for more than 15
continuous seconds;
(b) the yacht is within 300m of a mark;
(c) the yacht is within 30 seconds prior to and after tacking or gybing;
(d) the yacht is sailing less than 15 knots;
(e) the yacht is sailing at less than 90% of its performance relative to the other yacht(s);
(f) the yacht is taking a penalty.

That's probably why you and SA weren't a good fit. 😉

http://www.sail-world.com/USA/Ameri... ts-AC72-can-foil-sailing-downwind/101812

Excellent article on the technology, broadcast television, speed, close up racing, etc. Plus read about the involvement and background of a key player named Stan Honey.
Making the America's Cup a spectator sport

See how the C-class helped shape the current AC platform.

Those two videos are very interesting, and you see what happens at 2:15 on the last one, when they stuff the bows!

I liked the other video above too, where Juan K talks about the C Class, and says

...what have we been doing the past 20 years, these things are so much more efficient!

(wing rigs).

BUT...we know the C Class did try foiling for awhile, and they gave up on it, right? It wasn't paying off on a closed course, right? Or are some of them still doing it around the bouys? Grant Dalton mentions he's not sure if foiling will pay off on a short bouy type course.

SO...are we seeing

The Next BIG Thing

here, in the evolution of sailing technology, and when can I get some L foils and a wing rig for my F16? ;^)

Like I said a long time ago, just hook two Moths together and off we go!

Listening to the comments surrounding the teams, my guess is that they are going to be shooting for a semi-foiling mode off the wind and a near full flotation mode upwind. There is a happy point between weight, available power, and efficient foiling. I think the Moth's are just able to come in under this point with one very light (single-hull) boat so they can foil all the way around a race course efficiently. I don't think we have the technology to have a boat light enough to do this on much of a larger scale yet. While we can definitely build a catamaran to foil to weather, it's suffers with wind and water drag to carry it's own weight. It's going to either sail slowly as the foil drag increases with reduced speed or have to sail so far off the wind in order to keep enough power to stay on foils that same water-borne craft will get to A-mark faster because it can sail much higher.

So, if you give up fully foiling to weather, you have to look at how much foil drag you are willing to carry up to A-mark so you can rocket downwind. My bet is that the happy-point is going to be having just enough foil to make the boat really light on the water while going downwind without becoming completely air-borne on foils. This might also make sense given the fact that they aren't allowed any type of active control surfaces under the water and their racing area is a really choppy piece of water.

The

S

boards on NZ are a good indication of this as well (they can change the angle of attack of the horizontal part of their foil as they lift it).

Then again, I could be completely wrong.

Timbo,
In reference to the C's foiling not working, Magnus Clarke said he thought that the extra horsepower of the AC45's and 72s could remedy the problems they had with

off yer rocker

, so I wouldn't compare C's to the 45s or 72s .Apples and Oranges.

I think it's funny that they need a powerboat with 1200 horsepower to keep up with the AC72... talk about carbon footprint <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />

Another question popped into my head. Would slapping a wing on a

regular

catamaran cause problems since it can generate so much more speed, forcing the semi-displacement hulls into a pitch-pole?

Well...Ben Hall did it a couple years ago on his A cat.

I don't recall pitch-poling to be a problem but maybe some of the A cat guys who raced against him can tell us why he eventually dropped it in favor of a tradional mast/sail combo.