DYNAMIC BEHAVIORS OF MULTI-MOORED VESSELS IN BEAM SEAS

Model tests were conducted at IHI's ship model basin on the motions and dynamically varying tensions of moored vessels in regular and irregular waves, and nonlinear calculations of dynamic behaviors of moored vessels were also carried out. As a result of the studies, the following conclusions were reached. Due to the existence of mooring lines, coupled forces of sway and roll act on the heave motion of moored vessels. Due to the existence of steady displacements caused by steady forces, conventional linear calculations are apt to underestimate the mooring lines' tensions. Nonlinear damping coefficients are very influential factors on the prediction of the responses of sway and roll in a low-frequency domain. Slowly varying motions of moored vessels exist as transient motions for a long period, which are directly proportional to the frequencies of exciting forces and inversely proportional to the spring constants of mooring lines.