The purpose of this research is to find the practical methods to predict the course stability of towed offshore structures in the early design stage. The equilibrium yaw angles of the towed FPSOs with single skeg and twin skegs are predicted by CFD analysis and towing simulations using CFD are performed. The prediction results are compared with the towing model test results. Furthermore, the mechanism of instability is analyzed through investigation of the physical quantities from CFD.