Design research on the semi-taut mooring system in deep water

The effects of different design basis on the structure design of semi-taut mooring lines in deep water are studied in this paper,such as water depth,Vertical load capacity of anchor and the permitted horizontal offset of platform. As an example,a catenary mooring system and a semi-taut mooring system are designed for a deep water FDPSO platform and the dynamic responses of the coupled systems are compared. Compared with the traditional catenary mooring system,the semi-taut mooring system can reduce the footprint and payload,and the total steel quantity of mooring system can also be saved efficiently.Otherwise,the nonlinear effects in restoring stiffness of the mooring system will be increased which may cause the sudden increasing of tension. Enough attention should be paid on the phenomenon the design stage.