Study on effects of truncation and scaling of mooring lines of a FPSO

FPSOs are widely used offshore structures, primarily due to their versatility and portability. The analysis of a FPSO is conducted in the realm of computer simulations and wave basin based model experiment studies. Although scaling down of a prototype to an experimental model is the crux of wave basin studies, most wave basins lack the necessary dimension in depth to handle it. So, the mooring lines need to be truncated first and then scaled down to suit the wave basin depth. In this paper, a typical FPSO of 300m length (with 3x3 mooring lines at 120° spacing) at a water depth of 1000m is considered as the prototype model. Then a corresponding truncated model is generated to suit a water depth of 300m. The dynamic analysis of the above two models (prototype and truncated-prototype) are carried out in ANSYS AQWA and their results are compared. To compare the experimental results obtained in a 3m deep wave basin, available at the Department of Ocean Engineering, IIT Madras, the truncated-prototype model details are scaled down by using 1:100 scale.