The Wave Drifting Force Acting on Ships in Berthing Condition

Abstract

Pilots and tugboat captains point out that the towing ability of tugboat clearly declines in waves. This is important comment on operating safe and effective berthing maneuver. However, results of model experiments using water tank indicated that the towing ability of tugboat in waves did not decline scarcely (ref. (2) and (3)). So we have to check the steady wave force such as the wave drifting force acting on a towed ship in waves. But the influence of waves on the wave drifting force has not been examined because the waves around berth are very small comparing with the size of towed ships and waves in the ocean. In this paper, the physical mechanism causing the wave drifting force is verified and next some characteristics of the wave drifting force are discussed using results of model experiments. And then the wave drifting force for full-size fhips is examined. Finally, it is noticed that the wave drifting force is one of important external forces similar to the forces due to the wind and the current, in berthing maneuver.