i think this 'blackbird' is designed to be legal at the moment. i remember reading a post on standamarans (which i now can't find) that said that whatever legal body was governing the sport would allow any depth concave bottom as long as it was part of the moulded shape.
so the ron house shown below with seperate hulls joined by tubes is out as would be trimaraman outriggers. but the SIC one piece cat is OK. and the new corebans can have their long deep bottom concave
pete