The Dynamics of a Ship Moored by a Cable System Under Sea State Excitation

Abstract : An analytic study is made of a multi-leg buoy-moored ship in deep water waves. The equation of motion for a free floating ship is combined with the catenary equations for mooring lines to model mathematically the moored-ship system. The seaway excitations consist of very large first order forces at wave frequencies and smaller second order forces or drift forces at near zero frequencies. The results of a computer study of a moored Mariner Class ship in waves show that, for a large ship, the mooring system has little influence on the motions at wave frequencies and are essentially the same as those of the unrestrained ship. (Author)