I'm no boat designer but the stresses change a lot on a design when you add length to it, especially in front of the main beam. Darryl Barrett and Berny on the F14 forum have some great F14 designs and the hulls are the cheapest part by a long way.
Jeff Southall Current boats Nacra 5.8 1703 Animal Scanning Services Nacra 5.8 1667 Ram Raider Nacra 18 Square Arrow 1576