Modeling And Simulation Of Semi-submersible Ships Maneuvering

With the increasing of ocean resource exploitation all over the world, the demand of semi-submersible vessel is growing, but only a few countries can built this kind of ship. At the same time the research work on maneuverability of the pod-style semi-submersible vessel has just sprung up. Therefore, design a simulator based on pod propulsion semi-submersible ship is of very important significance recently.Ship motion mathematics model is the core of the ship simulator. There are two ways to build a ship maneuvering mathematical model in general. From the kinetic theory, a MMG model based on the semi-submersible vessels was set up; with the control theory, a response model was established at the same time.Firstly, with the kinetic theory, this paper has been analyzed and summarized the research achievement that is maneuverability of the pod propulsion semi-submersible ship published on public in recent years. A 3-DOF ship motion mathematical model was established pod propulsion based on semi-submersible ship. It is established calculation model that includes hull hydrodynamic, pod propeller hydrodynamic, propeller thrust and torque and so on. At last, with method of Rounge-Kutta, It is very easily to solve a real-time ship motion state.Secondly, with the ship zig-zag test results, the value of K,T which is called ship handling performance index can be calculated. A NOMOTO equation is established that input rudder angle and ship speed, and ship state as the output.Finally, in order to validating the model and comparing the MMG model and NOMOTO model, the paper takes the Heavy Lift carrier "Tai An Kou" for COSCO as an example. For the MMG model and NOMOTO model, turning cycle tests simulation were performed respectively. For more realistic, the paper also takes into account the sea surroundings including wind, wave and current influence. The results of the tests indicate that the established mathematical model is correct and effective; MMG model is more accurate than NOMOTO model to describe the motion characteristics of pod propulsion semi-submersible vessel.The mathematical model established in this paper is useful for research and development of pod-propelled ship operation simulator and sailor training.