Numerical study on the hydrodynamic effect of the SBT on the motion response of the low motion FPSO

Abstract

The Low Motion FPSO (LM-FPSO) is a new concept design which has noticeably low heave motion response compared to the general ship shaped FPSO. LM-FPSO is able to utilize Top-Tensioned Risers (TTRs) or Steel Catenary Risers (SCRs). The remarkable feature of the LM-FPSO is a Solid Ballast Tank (SBT) which is located under main hull and is connected with tendons. According to the recent study, the SBT improves the motion response of the LM-FPSO because the added mass and damping increase due to the SBT. The natural period also increases approximately double that of hull without SBT. The main purpose of this study is to investigate the hydrodynamic effect of various shape, dimension and structure of the SBT, which is related with heave motion response of the LM-FPSO. Rectangular shaped SBT is selected as base model. The frequency domain analysis and time domain analysis were conducted by using KRISO's LINDO and MOLINA, respectively. The comparative study was performed by changing the type of the SBT. The heave damping of the LM-FPSO was obtained by a model test. Copyright ？ 2017 by the International Society of Offshore and Polar Engineers (ISOPE).