The Prout 85S PD achieves the strength essential in catamaran design by bonding the bulkheads into a one piece hull molding to form deep box sections and then by bonding the one piece deck molding to the hull and bulkheads to create a monocoque shell system. The hull has integrated longitudinal and transverse mini-nacelles designed specifically to increase stiffness. The bulkheads are strategically located to absorb torsion and compression loads inherent in a catamaran's structure. The mainmast support bulkhead is mounted on a stringer to help transmit the mast loads away from the bridge deck. The hulls are hand laid with E-Glass and isophathalic resin to German Lloyds recommendations. The first layers use powder bound mat and vinylester resin to minimize risk of osmosis. The hull is cored above the waterline with foam core. The deck is molded using similar techniques of foam core reinforced at high stress areas with uni-directional and double bias cloth. All bulkheads and cabin soles are made of NIDA cored GRP laminate. Watertight bulkheads fore and aft add buoyancy and security in the event of collision and ensure the watertight integrity of the boat.