A Study on Suitable Mooring for Large and Small Ships during Waves and Winds

A suitable ship mooring achieves not only a safe mooring but also an economical and effective cargo handling operation. Moored ship motions are generated during waves, winds and other external forces. The excessive motions disturb the cargo handling operation and happen to derive some damages of the mooring lines and fenders. An empirical and traditional role of mooring such as a pretension mooring (a hard mooring) or a slacked mooring is operated on each size of ships on site. In this paper, field observations for 250, 000DWT class VLCC (Very Large Crude Carrier) and 3, 590DWT cargo ship were carried out. We observed the moored ship motions, waves and winds. As the results, the mooring methods for VLCC and 3, 590DWT ship were the pretension and slacked mooring which were as same as the empirical methods. Then, we tried to reproduce the moored ship motions of each observation using a numerical simulation method of moored ship motions. The objective of this study was to evaluate whether the empirical and traditional role of mooring was a suitable and reasonable mooring using the simulation. It focussed therefore on the ship motions and mooring loads corresponding to the pretensions of mooring lines.