Investigation Into Scale Effects on Motions and Mooring Forces of a Turret-Moored Tanker
A loaded 200 kDWT tanker moored by means of an internal bow-turret is exposed to survival conditions (colinearly directed irregular waves and wind). The water depth amounts to 82.5 m and the turret mooring system consists of 6 equally spaced chains.By means of time-domain computations of the coupled chain-mooring-tanker system the wave frequency (WF) and low frequency (LF) turret motions and chain/turret forces are simultaneously determined.The model tests were carried out on scale 82.5. The results of the computations are compared with the results of the model tests using the wave registration as calibrated in the basin. The comparison required the modelling of some additional damping which is expected to originate from small sway and yaw motions which were measured during the model test.Investigations on scale effects in the resistance coefficients of the hull in surge direction are presented. Finally the sensitivity to changes in the values of the drag and inertia coefficients of the chains on the mooring loads in the chains and turret construction is given.