Capability plots of dynamic positioning for the semi-submersible platform in internal solitary waves

Abstract

Based on the experimentally detected forces induced by internal solitary waves (ISWs), an analysis on capability of dynamic positioning (DP) for the semi-submersible platform model under the influence of different ISW-amplitudes with three kinds of ocean stratified conditions is carried out. The environmental forces acting on the semi-submersible platform arise due to the following two main components: the measurements of ISW-forces and calculations of the wind, currents and waves. Combined with quadratic programming (QP) methods, extreme safe amplitudes under different upper layer depths and the DP strategy are proposed. It is obvious from the experimental results that both the maximum and minimum horizontal ISW-forces increase linearly with the wave amplitudes under different layer thickness ratios, and the upper layer depth has a significant effect on the ISW-forces. Reference to the obtained results from the DP capability simulation reveals that the maximum thrust, with overloading, appears at heading angles of 90[Formula: see text] and 270[Formula: see text] under different upper layer depths, whilst the minimum thrust is under angles of 0[Formula: see text] and 180[Formula: see text].