Experimental study of multi-buoy-assisted moored ship motion at open berth

Abstract

Cable breaking and fender failure are frequently reported for the traditional moored ship at open berths. An effective mooring system is necessary to optimize the distribution of cable tension and reduce the impact force acting on the fender. In this paper, a multi-buoy-assisted mooring system is proposed to improve the safety performance of the moored ship. Based on the traditional mooring system, two or four buoys are added in the offshore direction of the ship and connected to the ship with the additional mooring lines. Physical model tests of a 180,000-dwt bulk cargo ship are carried out with the different mooring conditions. The cable tensions, the fender reaction forces and the corresponding ship motions in six degrees of freedom are measured under the different mooring conditions. By adjusting the number of buoys and the pretension of the buoy-assisted mooring lines, an effective mooring system for the tested ship is developed. The experimental results indicate that the developed mooring system can effectively prevent the cable breakage and the fender damage under the present test conditions. In addition, although the motion amplitude of the multi-buoy-assisted moored ship increases slightly, the motion velocity of the ship is considerably small, and the influence is limited for the load and unload operations of the bulk cargo ship.