Abstract: A catamaran vessel with a pair of spaced apart, parallel hulls which are made of sealed watertight configuration of composite marine material and interconnected by a deck and cabin structure with depending stilts joined to the hulls. The hulls have a wave piercing configuration in which the length to beam or fineness ratio of each hull is approximately 16.3:1 with a prow that is essentially knife-edged and vertical, the vertical section contours of the forward portion of the hull are elliptical and gradually transition to an essentially rectangular contour along the rear portion. The underside of the deck between the stilts has a convex undersurface which constitutes a planing hull structure above the top of the pair of hulls and between the stilts. The depicted vessel is power driven by motor-driven propellers at the stern of each hull.