RMcKnee wrote
Hah! I think you know more than you are admitting to. As far as my understanding of how boards work, everytime I think I understand, something else comes along and tells me I don't understand nothing (forgive the triple negative) As far as displacment hulls, there's probably a point where they start to plane and lift the rest of the board out of the water? Or they plane once the board is at the correct angle in the turn.?I can't really begin to pretend I understand the hydrodynamics of surfboard design in any more depth than I've already attempted on this thread. My limited grasp of the matter in question is that a displacement hull sits down in the water while a flat bottom provides a platform that planes over the surface of the water once moving at sufficient speed.
I think the photograph lies a bit as far as the rails go. There is a resin edge that I assume most boards have. The business end rails just before the fins are very 'down' rails and the edge is crisp enough to shave ;)That really crisps things up, but you can't see it in the picture... As far as the catamaran thing, you are perfectly right . The board "runs" to use a n expression of Dp's.What I was getting at re your deep concave was the idea that when the board's planing it's riding on the two outer edges of the bottom, rather like a catamaran. Looking at the rail shape in cross-section it appears really like a very rounded shape, similar to the old 50/50 rail, also similar to what GG used in the front half of Velo and similar spoons. I just didn't see any defined edge there at all and was wondering.
One thing I haven't got used to is the board still planes when you don't expect it too. Like when the wave is gutless and you are out on the flats - weird.
sorry once again for the typing... I can only see the first paragraph and the rest is by feel (: