This paper describes a system for predicting the wave height distribution and movement of moored ships in harbour. The system has been developed to contribute to the planning and construction of harbour facilities and to improve the safety and efficiency of ship mooring and cargo handling operations in ocean facing harbours.
　The input system is simplified. Even if the detailed properties of moored ships are unknown, the system can determine these data from several information. The motion of the moored ships is calculated by considering the effect of reflected and refracted complex waves. The calculation results which appear on the monitor include the time history of the motions of moored ships and warnings issued when allowable values such as motions or tension of mooring ropes are exceeded.