Simulation Study On The Semi-submersible Ships Maneuvering

With the increasing of offshore oil exploitation efforts in the world,the demand of semi-submerged vessel is growing.Currently,the number of seagoing semi-submerged vessels are only more than 30 around the world,because of the special nature of this kind of ship,the ship industries are lack of perceptual knowledge,and lack of understanding of the study of manoeuvrability.Therefore,for the safety and efficient ship's maneuvering,the study of semi-submerged vessel becomes especially important.In order to establishing the maneuvering mathematical model of the semi-submerged vessel with POD propulsion more accurately,this paper bases on the combination of Kijima model and Yoshimura model.The model is suitable for the entire maneuvering range including normal speed,low speed,small and large drift angle and so on.,and the effect of shallow water is also well considered.In the model the characteristics and principle of POD propeller are being studied,and consulting Z type propeller principle,then establishing mathematic modelof POD propeller,in the motion mathematic model of submerged vessel overlaying whose propulsive force as the outside force,and considering the hull,oar force and force moment sufficiently,and mutual interference.In the condition of normal speed,hydrodynamic force is calculated by Kijima model,then this paper simulates the motion of turning and direct way the simulation results show that the mathematical model can reflect the motion of semi-submered vessel.In the condition of low speed,hydrodynamic force was calculated by Yoshimura model.By regulating the maneuvering angle of POD propeller,this paper attains the turning motion of semi-submered vessel on the original place.The results show that semi-submerged vessel with POD propulsion has excellent maneuverability.