<< The fastest sailing boat in the world is a planing proa>>

We're getting into semantics here: http://www.wired.com/2013/01/ff-paul-larsen-sailrocket/all/

" Despite the fact that his instrument cluster isn’t working, Larsen carves the turn perfectly. We accelerate the whole way. Except for the lack of engine noise, I can’t believe we’re not in a speedboat. SailRocket is starting to vibrate, hard. The boat’s three pods are sending up three Jet Ski-like rooster tails of spray. And then, suddenly, there are only two rooster tails—the wing has pulled the rear pod completely free of the water. I know this is what’s supposed to happen at 26 knots—the second crucial transition—but it’s alarming to feel the boat surge ahead once again. We’ve just shed a full third of our hull drag.

Larsen completes the turn somewhere between 30 and 40 knots, just in front of the sandbar. We’re out of the chop now, and the flat conditions give us another burst of speed. The zodiac, which had been chasing us, has now fallen far behind. Another few seconds, and a glance to the boat’s opposite side reveals that we’ve made the third crucial transition: the point very close to 45 knots when the leeward pod, the one under the wing, lifts free and takes to the air. SailRocket is now more plane than boat. We’re bombing along on just the front pod and the foil. There’s not much more wetted area than you’d find on a boogie board, and yet cantilevered behind that front pod is a massive machine—40 feet long and 40 feet wide."

Anyway, I don't accept the argument that the fastest things in the world don't (or merely incidentally) use foils therefore, by implication, we can find better ways.  Earlier in this thread I discussed at length (and drew attention to all that Tom Speer has said concerning) the merits of foils for higher speed, increased stability and seaworthiness, and for sea kindly motion - something I wouldn't describe planning craft as having.  So I'm not about to repeat those points.

These other matters aside, foiling is the proven way of increasing speed of sailing craft.  I don't need to go into what foiling has done for C-Fly, Moths, C Class and of course AC72.  Foiling is accessible.  It has its pitfalls, but these represent challenges that inspire me.  If you're interested in improving performance and motion, but not interested in hitting 40 knots then I can't see a better way.  I'm not saying there isn't one, but I can't see it.

I've already seen your proa video and the craft is impressive.  What bi-directional profiles do you advocate?

I'm very familiar with all things vector foil and canted rigs.  The vector foil is a great idea for pure speed but would not want to see it come out of the water (fouled or otherwise).

I'm presuming from your latest post, perhaps incorrectly, that you have no further critique of my foil exploration specifics and the uncertainties involved as I've articulated them?  Your critique has been helpful, even if we disagree concerning future directions.

I've compared my foils to Speer's H105 at Reynold's 4M and my foils maintain Cp > -0.6 through almost 6 degrees compared to less than 4 for the H105.

I'm drawing up some new ideas to see if I can further widen the pressure envelope.

David

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