Kinda defeats the purpose if you add weight to it doesn't it? An RC cat (or tri) can be a lot of fun but it has to be VERY responsive, it's length to width ratio needs to be very refined (so it flies a hull before it pitchpoles), and the sails need to be right. If they're light, they'll skate across the water at incredible speeds. After this round of US1M, I'm probably going to build a super-light trimaran...perhaps with a rigid wing (easy to do using model airplane techniques).