An easier way to draw and shape a catamaran or trimaran hull. It dispenses with most of the labor involved with lofting and fairing hull lines. Instead of laying down a full set of waterlines, half breadths, sections and diagonals on the lofting floor, this method uses only three lines - keel, sheer, and a single chine. Also, producing the full size hull shape by carving foam is fool proof because the keel, shear, and chine serve as guides.