Pete,

My guess is that you are correct, but nobody likes the look of the result. For example, look at the Itzacat design (http://www.youtube.com/watch?v=JbOr46fV4n0) Basically two surfboards lashed together with a sail in the middle. The beams are mounted in such a way that even when the boat has a hull in the air, the one in the water pivots so it is still flat on the surface.

As the writeup to the video says, it "... sold well to engineers and science teachers who understood why it worked so effectively." The rest of us just said, "Eww."