Authors performed various kinds of onboard experiments concerning the hull strength of a very large container ship. Following results were obtained by the experiment. 1) Short term distribution of wave-induced longitudinal stress on the upper deck follows Rayleigh's distribution. 2) Longitudinal bending moment in irregular waves can be estimated by the calculation for regular waves using the significant wave length and height. 3) Stress on the upper deck caused by warping can not be neglected. 4) Athwartship motion of containers in the hold is not always induced by rolling only. 5) Authors' calculation method for hydrodynamic pressure can be applicable to actual ships, but, in this case, wave spectrum should be estimated as accurately as possible.
