A Consideration on the Personnel Transfer from a CTV to a Floating Substation

Abstract

　This paper presents an assessment of the performance of a Crew Transfer Vessel (CTV) in transfer mode to a floating substation using P-plot chart and discusses on the influence of the motion characteristics of the CTV and her horizontal fender force. The results suggested that there is almost no shielding effect of the structure at the slip limit and the effect of floating substation's motion is small on the CTV motion. In addition, the difference of slip characteristic due to the berthing direction is small, and the slip limit value is higher in the floating type than in the fixed substation. Three different joint's torsional stiffness around the z-axis has been tried and it is found that the influence on the P-plot based only on the vertical joint force is small, which implies that the symmetrical and antisymmetrical motions are not coupled even when she is berthing. On the other hand, the effect of torsional stiffness is clearly appeared in the antisymmetric motion spectrum and the joint horizontal force. As a result, the torsional stiffness has generally a considerable effect on the slip limit considering both the vertical and the horizontal joint forces except for a small torsional stiffness. The wave surface elevation and the rotation of the floating substation due to the berthing of the CTV are also discussed as other factors.