EXPERIMENTAL STUDY OF CHARACTERISTICS OF MOTIONS OF A LARGE MOORING SHIP IN LONG-PERIOD WAVES

Abstract

By inviting the method of physical model tests, the characteristics of mooring ships' 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 have got natural periods of their own; the movement of sway is a kind of periodic motion. The ratio of the natural period of sway and the natural rolling period of the mooring ship is within 1.11~1.23. The peak value of sway grows along with the increase of the wave period; the regularities of the LNG ship's movement of heave are basically the same along with the periodic changes of waves, although the loading conditions are different. The peak value of heave is greater than the wave height; the ship's movement of pitch is affected little by the changes of periods of the transverse waves; the movement of roll is a kind of periodic change. The ratio of the natural periods of roll and the natural rolling period of the mooring ship is within 1.23~1.48. The peak value of roll grows along with the increase of wave period.