Abstract: Floating Production Storage and Offloading (FPSO) units are critical equipment in offshore oil development. When mooring at a dock in harsh environmental conditions such as typhoons, their large main dimensions and simultaneous exposure to combined wind, wave, and current forces impose high demands on the load-bearing capacity of the mooring system. Additionally, the mooring lines are arranged in a complex manner, with nearly 60 lines, making it almost infeasible to use a comparative method to find the optimal parameter combination for all mooring lines due to the extensive computational workload. Therefore, this paper comprehensively considers the multi-directional wind, wave, and current loads and develops an iterative optimization method for FPSO typhoon-resistant mooring line system parameters based on an improved genetic algorithm. The method takes line lengths as variable parameters, and different combinations of line lengths as individuals in the genetic iteration. By checking each combination's line load under typical conditions to assess the fitness of the combination, the optimization is iteratively carried out, ultimately resulting in an optimized mooring line system. The comparison of the mooring scheme results before and after optimization reveals that the optimized mooring line length parameters show a trend of tightening longer lines and relaxing shorter lines, thus improving the utilization of lines that previously had lower loads. The optimized mooring scheme reduces the maximum mooring line load under all conditions by 12.2% without significantly affecting the amplitude of FPSO movements. By merely adjusting the tension levels of the mooring lines, the optimized scheme meets safety standard checks without altering other parameters. This optimization method can enhance the safety of mooring systems within the constraints of limited dock resources and provide a reference for docking mooring operations.

Key words: Docking mooring, mooring lines force, genetic algorithms, parameter optimization, time domain calculation