Oh wow, a boat is a black whole which absorbs energy. Did you ever thought what happens, when structures reflect after removing a load? [/quote]

I think you may have misunderstood what I was saying. The structure of the platform absorbs the energy as it twists. As it flexes back again not all that energy is transferred to smooth foward motion. Some of it simply results in the boat bobbing up and down in the water. The objective is to not have that twisting and untwisting motion at all so all the energy is applied to forward motion. Much as we try to sail a boat as smoothly as possible in choppy water by such things as footing off a bit, powering the rig up slightly and structural things like lighter masts and sails.
If the theory of not worrying too much about flex in platforms were correct we would all be happy sailing two year old Hobie 16's!