Dynamic positioning capability (DPCap) analysis is a traditional method to verify a DP vessel’s ability to resist the environmental conditions for given headings. However, DPCap analysis is inherently quasi-static, the environmental forces are statically balanced by the thrust forces provided by the thrust system. Dynamic station-keeping capability (DynCap) analysis can provide a more detailed study of a vessel’s station keeping capability in realistic dynamic conditions. DynCap analysis is based on a DP simulator, which is absolutely dynamic and relatively realistic. However, since the numerical simulation based on the simulator is more time-consuming compared to the static analysis, the selection of the environmental condition sequence becomes critically important to the efficiency of the DynCap analysis. This paper proposes application of the bisection method to achieve the environmental condition limit and a controller gain database method to tune the control parameters in the DP simulator. The efficiency of the DynCap analysis is expected to be improved. Numerical analyses for a semi-submersible were conducted to investigate the performance of a program developed based on the present study. The feasibility of the program and the effectiveness and efficiency of the methods were both demonstrated.

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