The major problem in designing a ship with wide and long hatch openings, such as a container ship, is to clear her torsional behaviour.
Many investigations have been done in regard to this problems. But these are all restricted themselves within rather a simple hull structure. It is, therefore, difficult to clear the torsional behaviour of above mentioned ship by applying the results of investigations published before.
In this paper, the authors try to establish the method of theoretical calculation for the torsional behaviour of the ship holding her structural characteristics and then to verify the reliability of the method of calculation by the torsion test on models. The results of the torsion test are analyzed according to above mentioned method and the following items are found conclusively.
(1) The torsional behaviour of such a ship can be well characterized and estimated by the method of theoretical calculation developed here.
(2) The distortion component of hatch opening due to warping of the cross section can not be neglected comparing to the ones due to change of the transverse displacement at the deck level.
(3) The corner stress due to distortion of hatch opening reaches its maximum at the end of the cross deck where the opening is changing its width from wider opening into narrower one.
