Analysis of Catenary Mooring Systems Based on Truncated Mooring Experiments

Considering the activities of floating systems pushing to the ultra-deepwater, the full scale mooring system needs to be truncated in order to carry out model tests in wave basin with reasonable model scale. In this paper, a Semi-Submersible moored by a catenary mooring system, which operates in 1500m water depth is truncated at 200m water depth. The mooring induced damping of truncated mooring system and prototype mooring system in 100 year typhoon condition in South China Sea are studied experimentally and numerically. The de-couple technique is applied to obtain truncated mooring damping, which is implemented by inputting the vessel six DOF motion responses and solving the mooring tensions, then decompose mooring tension in x, y and z directions. The vessel six DOF motion responses were measured in the model tests. For the full depth mooring system, the fully coupled dynamic analysis is carried out to study mooring induced damping. The results of truncated mooring damping will be compared with full depth mooring damping.