Midship Bending and Torsional Moments of a Container Ship in Oblique Waves

Abstract

Since container ships have large deck openings on their slender hulls, it is very important to estimate the wave loads, or torsional and bending moment, as accurately as possible for designing such a vessel. Though some experimental as well as theoretical investigations with regard to this problem have recently been carried out, the comparison between the theory and the experiment seem still insufficient to apply the theory to the practical use, except the vertical bending moment. In this paper the authors investigate the vertical and lateral bending moment as well as the torsional moment acting on the midship section of a container ship, using the results obtained by the model tests and the theoretical calculations based on the so called strip method, which cover wide range of wave conditions and ship speed in oblique regular waves. The results show that the theory agrees rather well with experiment for vertical and lateral bending moments, while discrepancy is remarkable for the torsional moment in quartering seas. The steady deviation of the vertical bending moment in still water and in waves and the combined bending moment induced by the vertical and lateral bending are also described with the experimental data.