OK, so we've decided stiffer is better, now, my question to the Engineers is: Which shape beam would be stiffer in our application, a round beam or a square beam or a trapazoid? I mean, our beams have (at least) two different directional forces acting on them, up and down type flex, but twisting as well.

If there were some way to make them stay perfectly seated to their hulls with zero movement there (glued, like the A cats) would a box beam twist and flex more or less than a round beam, or oval beam, given the same relative size, weight and wall thikness?

I don't see any racing bicycles built with box shaped tubes, or perfectly round tubes any more, most are oval. I know some of that oval shape is for less wind resistance, but we could all use less wind (and water) resistance when we stuff the front beam into a wave, right?