On the Motions of High-Speed Container Ships in Oblique Waves : About the Single and Twin Screw Ships of L/B=8

Abstract

Container ships as a high-speed liner are becoming faster and larger so that the ship form becomes more slender, having more number of propellers. This paper deals with the motions of such vessels in oblique regular waves by means of both model tests in the seakeeping tank and theoretical calculations based on the so-called strip method. The model tests were carried out for two types of ships whose length-breadth ratio (L/B) is eight, having single and twin propellers. The test results are compared with each other as well as with those obtained recently for a container ship whose L/B is 6.89. They are also compared with the computed results by the new strip method which has been recently developed by N.Salvesen and others or F.Tasai. As the result, the effects of L/B on ship motions are clarified. The agreement between experiments and theory are very good for vertical motions in every wave direction and for lateral motions in beam and bow waves, while the difference is rather remarkable for lateral motions in quartering waves.