Well, I don't know if I could apply the all the math from some of the recent threads on RM, HM, etc., but I did have a chance to take a proa on her maiden voyage today (see photo in attachment). The word I heard most from curious onlookers was "interesting".
20 feet long, 14 foot beam, 200 sq ft of sail, and a rudder at either end. You don't tack a proa, but rather you "shunt" them (steer to a reaching heading, release the sheets so that both masts pivot to leeward, pull one rudder, drop the other, sheet in the opposite set of blocks, and go. It was rather strange in that no matter what point of sail we were on, the view is always to leeward.
Did you get a chance to helm it?, if so how did it feel, I am told that with that rig set up you don't need rudders.
Is it a production boat or a home build?
Hi Kevin
Looks much like some of the earlier Proa designs ,-
Some singlehanded across the Atlantic in Ostar races ,
check some of the multihull design books on the Ostar races in earlier decades of multihull design development
http:/
Singlehanded across the Atlantic -
-Some really good Newic Tris --huge monohulls -sailed by one ,--
and some of the first really large cat designs,-predicessors of the round the globe current racers ,-- along with a proa or two in the early days of the race.
more recent-{hi tech } version proas are attempting the sailing speed records
Looks like fun , sail both directions ? just reverse your bow and stern to tack ,-it would take some getting used to .
Way cool to see another one of these has been built!
I attended a seminar by the owner of Chesapeake Light Craft on stitch and glue construction. His presentation highlighted all the construction methods with examples from some of their very well designed kits. He had an 18 foot racing kayak there that was simply beautiful and very light/strong. But the thrill of the presentation for me was when he showed this proa design as a bit of an afterthought. Always great to uncover multihull enthusiasts! At the time he didn't say that he was going to make the plans available, and I asked him if was considering a catamaran based on a similar concept. He said he had thought about it, and if he did it it would be plans and not a kit. Keeping my fingers crossed...
Check out "Cheers" -- http://www.wingo.com/newick/
Looks like fun , sail both directions ? just reverse your bow and stern to tack ,-it would take some getting used to .
Carl,
When we pushed off I half expected the boat to break up in the middle of the bay. We were out in winds of 18-20k and had the sails deeply reefed. The thing was actually very comfortable to sail. Since this is only the second one to be built of this design, there were several things that the boatbuilder was still sorting out in his shop during construction. (Then, we had to make a few more modifications on water's edge prior to the launch.)
Tacking (or, as they call it with the proa, "shunting") is not a manuver that takes mere seconds. The process takes closer to a minute. Not gonna win many races that way 
"Not gonna win many races that way"
Then again, if you were only sailing against other Proas, the playing field would be even. This would sure make for some "interesting" tacking (sorry shunting) duels!
Sheldon
I wonder if the same tacking rules apply to shunting!? 
Can you drive somebody out to the corners?
Is it a production boat or a home build?
I was on the helm half the time. (There's a tiller at either end.) It has a very balanced feel, however when you first sheet in after "shunting", she wants to round up pretty good (even when only sheeting the forward sail). Once she's moving, you can steer pretty easily with the sails.
The design is by Chesapeake Light Craft. There was one prototype built that had wing masts. The boat I was on was the second one built. It was ordered by a man in Chicago and built by Two Daughters Boatworks here in Vermont. Wood/epoxy construction, hollow wooden masts.
After I posted this I realized that it was stated incorrectly. (Actually I was just testing all of you to see if you'd pick up on my error. Yes, someone did 
)What I meant to say was that you are always looking at the same hull. There's no switching sides. The boat is set up to control all sheeting and the tillers from the smaller windward outrigger hull, so there's no crossing over after a tack (er, I mean shunt)