Static pressure tests on sections of yacht hulls, manufactured to copy the structure of certain yachts which failed in service due to slamming loads, are reported. The materials of construction were aluminum, steel, plywood and fiberglass. The failure modes and pressures are discussed. In addition, some tests in which mild steel plates, corresponding in construction to the mild steel hull tested under static pressure, were loaded impulsively by the shock wave from an explosive charge detonated in air. The design of hull plating should take into account the impulsive nature of the loading, and the actual mode of failure. Neither the design impulse, however, nor the means for predicting the hull plating response to it are available from the current literature. If resort is to be made to the design of plating for simple static pressure, then a design pressure of at least 350 kPa (51 psi) is suggested for the bottom plating of yachts of about 13 m (43 ft) length overall. This is about five times the pressure required by the ABS Guide.