Quay Wall Influence on Passing-Ship Induced Mooring Loads

The forces and moments induced on a moored ship by a passing ship are of great concern. Past model tests and analyses have addressed the passing-ship problem in an open waterway, without bank effects and without channel width restrictions. This paper reports on passing-ship effect results calculated with a hydrodynamic computer program model. The computer model was validated by comparison with published results from passing ship model test for the open water case. The computer model was then used to analyze cases with the ship moored alongside a vertical quay wall and in a narrow restricted channel. The passing-ship forces and moments are markedly altered from those in the open-waterway case by the presence of the quay wall and the narrow channel. Surge forces are essentially doubled. Sway forces and yaw moments are essentially halved. As a result, the motion response of the moored ship would be substantially different and the peak loads in mooring lines could be substantially greater. These findings are of great significance in the design of quay-wall-side, narrow channel, and near-shore pier mooring systems.