Influence of large hull deformations on the motion response of a fast catamaran craft with varying stiffness

The bow and the aft part of the boat acquire a combination of permanent and dynamic deformations. Both of them have the same effect, a variation of the effective length of the boat. As a consequence of the shortening of the hull the pitch restoring moment and the heave resorting force will be reduced. So there will have to be bigger heave and pitch movements to compensate similar forces.