The Research And Simulation Of Williamson Turn For VLCC

Sometimes crew may accidentally fall overboard while the vessel is navigating in the sea. Once this situation happens and if it is discovered by someone onboard the vessel, the duty officer has to manipulate the emergency maneuvering of the vessel in order to rescue the crew overboard. In order to improve the effectiveness of rescue effort, the IMO Resolution A.601 claims that the vessel should carry out the test of MOB regularly and recommends 4 kinds of proposals for ship turning. Of these proposals, Williamson turn is the most useful one. In this thesis, this IMO-recommended Williamson turn is considered and called as the classic Williamson turn. Most of the masters working on the VLCC find that the classic Williamson turn is not applicable to the VLCC for its rescue operation of the man overboard. Therefore, in order to modify the classic Williamson turn and to ensure it is well-applicable to VLCC, it is necessary to study and analyze the special maneuverability of the VLCC.In this research, a mathematical model is established for the maneuverability of the VLCC. The MMG model has been adopted for its mature theory and it is still using until today. In order to ensure its accuracy, a real ordinary vessel and a real VLCC vessel are chosen for ship maneuverability test and their simulation results are compared. At the same time, wind disturbance, current force and wave force are added to the ship model to improve the simulation's accuracy. Considering the adverse factors of the traditional wind disturbance, a simplified simulation model for wind disturbance is put to use. On the other hand, a characteristic model-based ship mathematical model is established to study the vessel's maneuverability.The program of the vessel Williamson turn is implemented in the Matlab programming platform and it is used to analyze the ordinary vessel's Williamson turn and VLCC Williamson turn respectively. Through the simulation results, it is found that according to the classic Williamson turn, the ordinary vessel can return back to its initial route with almost no deviation, but the VLCC deviates from its initial route a Throughout the research and analysis of the VLCC Williamson turn, the disadvantage of the classic Williamson turn has been explored and it has been modified and enhanced. Through the modified Williamson turn, the VLCC can return back to its initial route in less deviation, and it is instructive and meaningful to the rescue effort of the VLCC.