Over stiffness in structures can lead to more problems than solve, glider design ( who probably lead the world in composite construction ) have now gone away from very stiff structures, it was leading to structural failure at key points ( stress fractures ) and many pilots felt that they were taking such a physical battering, they couldn't cope physically over longer flights. Food for thought and I would guess the super stiff boats must be nearing this point or is boat design still catching up.