Experimental Study of Characteristics of Motions of a Large Mooring Ship in Long-Period Waves

Abstract

By using the method of physical model tests, the characteristics of mooring ship's motion responses in transverse long-period waves have been studied under different conditions, including such elements as loading conditions, wave heights, and specific patterns of mooring, etc. The results indicate that: the mooring ship's movements of surge, sway and yaw had their own natural periods; the movement of sway was a period motion. The ratio of the natural period of sway and the natural rolling period of the mooring ship was within 1.11~1.23. The peak value of sway grew along with the increase of the wave period; the regularities of the LNG ship's movement of heave were basically the same along with the periodic changes of waves, although the loading conditions were different. The peak value of heave was greater than the wave height; the ship's movement of pitch was affected little by the changes of periods of the transverse waves; the movement of roll was a kind of periodic change. The ratio of the natural periods of roll and the natural rolling period of the mooring ship was within 1.23~1.48. The peak value of roll grew along with the increase of wave period.