A shallow water mooring system design methodology combining NSGA-II with the vessel-mooring coupled model

In this paper, a mooring system design methodology combining the Non-dominated Sorting Genetic Algorithm-II (NSGA-II) with the vessel-mooring coupled model is first proposed. In the proposed methodology, the multi-objective optimization problem for mooring system design which involves several design variables, objective functions and constraints is established and solved by the combination of the NSGA-II algorithm and the vessel-mooring coupled model, and the initial feasible range of design variables is narrowed in advance by combining the NSGA-II with the quasi-static mooring system model. A case study is presented to demonstrated the proposed methodology, in which a catenary mooring system is designed from scratch for a semi-submersible very large floating structure (VLFS) module. It can be concluded from the obtained results that, owing to the combination of the NSGA-II algorithm and the vessel-mooring coupled model, the accurate dynamic responses of vessel and mooring systems can be used as the objective functions; thus, the proposed methodology is able to attain an optimal mooring system considering more practical design requirements, such as the vessel motion response, the safety factor of the mooring system, the length of mooring line lay down part and mooring system layout. •This paper proposes a mooring system design methodology combining the NSGA-II with the vessel-mooring coupled model.•The initial feasible range of design variables is narrowed in advance by combining the NSGA-II with the quasi-static mooring system model.•The accurate dynamic responses of vessel and mooring system can be used as the objective functions by using of the proposed methodology.