Numerical Simulation of Hybrid Synthetic Mooring Lines Based on a Finite Difference Dynamic Model

Abstract For the deep-water mooring, the hybrid synthetic mooring lines (with chain-rope-chain configuration) are often used for their advantages in weight and cost against full steel chains. In this research, a finite difference dynamic model is developed for numerical simulations of hybrid synthetic mooring lines. The simulation model is validated by the single steel chain model experiments and “chain-rope-chain” mooring line simulations. Then, the validated model is used for the dynamic analysis of two mooring systems with 4 and 16 hybrid synthetic mooring lines. From the dynamic stiffness iteration of two mooring systems, it is found that the top tensions of the mooring lines arranged symmetrically about the y-axis has a phase difference of half a cycle, and their dynamic stiffnesses are very close. For the mooring system with “4 × 4” hybrid synthetic mooring lines, it is found that the smaller the angle between the mooring line and x-axis is, the larger change in top tension, and the smaller axial stiffness becomes, and the axial stiffness tends to a certain value as the number of iterations increase.