Comparison of time domain simulation methods for ship mooring arrangements

Sammanfattning

Safe and effective mooring of ships at berth is a critical aspect of port operations,affecting crew safety and vessel integrity as well as operational cost and efficiency. Ithas become a common practice to plan ships mooring arrangements in advance usingship dynamics prediction tools. This study employs two prediction tools, one based ona fully nonlinear potential flow method and the other on a semi-empirical method, forsimulating the dynamic behaviour of a moored ship in time domain. The simulationsare carried out for a barge with a simple geometry, subjected to the primaryenvironmental factors in ship mooring problems, namely wind, current and waves. Theisolated and combined effects of these environmental factors on the ship dynamics areinvestigated by analysing the ship motions as well as mooring lines tensions. Overall,the results obtained from the employed tools were comparable, while the semiempiricalmethod offered substantially faster calculations (lower computational costs)than the potential flow method. However, the study reveals that the lack of suitablemodels to account for quay wall effects on the moored ship within the semi-empiricalmethod can adversely affect the dynamic behaviour predictions, hence significantlyimpact the assessment of mooring line arrangement performance.