Study on Optimum Design of FPSO Spread Mooring System

초록

For a spread-moored FPSO(Floating Production Storage Off-loading) vessel subjected to environmental excitation from waves, current, and wind, a procedure to determine the optimum length and offset of mooring lines is suggested using quasi-static frequency domain response analyses. Coupled relations between design parameters are closely examined and optimized design parameters are proposed based on the minimum weight condition. The initial design parameters for numerical analyses are calculated using the static catenary equation of mooring lines. It is demonstrated that the line tension and vessel’s offset are influenced by the mooring line length and stiffness. Accordingly, it is suggested that the optimum vessel’s offset range should be determined considering line fatigue damage. The availability and limitations of the quasi-static analysis method in application to a spread mooring system are explained by comparing the results of a time domain analysis with those of a frequency domain analysis.