Computer Simulation of Moored Ship Behavior

Mathematical simulation models are of growing importance in the design stage and for the operation of mooring facilities at exposed locations. In this paper such a model is described for the prediction of motions and mooring loads of ships and other floating structures moored in irregular waves, wind, and current. The mathematical model is based on the equations of motion in the time domain. This approach allow nonlinear and asymmetric mooring loads and arbitrarily in time varying excitation of the vessel. Input variables are: environmental conditions; mooring layout; elasticity characteristics of mooring lines and fenders; and geometry of the vessel. Output information includes: time histories; spectra and statistical values of motions, and mooring loads. Results are presented of an extensive validation study on the behavior of a 200,000 TDW tanker moored to an offshore jetty in shallow water. From the results it may be concluded that there is good qualitative and quantitative agreement between the results of the computer model and the experimental results.