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UBC Theses and Dissertations

The simulation of ship maneuvering and course keeping with escort tug Li, Ye

Abstract

Ship maneuverability and its prediction in the early design stage become possible and important during the last 40 years as a result of some marine accidents involving large ships. Maneuverability standards were developed and proposed by the International Maritime Organization (IMO) which provides the ship maneuvering performance criteria. Ship simulation technology in particular simulation of ship maneuvering advanced well in recent years with the advent of computers. Computer programs using either numerically computed or experimentally determined hydrodynamics coefficients allowed for maneuverability simulations of different vessel types. Relatively good agreement was reported by various researchers between simulated results and those obtained from real ship trials. It seems that simulation can now identify acceptable ship maneuvering performance in calm seas. However the effects of the wind and the currents are not that well studied and reported while they are always important factors for ship maneuvering especially in restricted waters. The numerical simulation presented in this thesis classifies "good" ships and "bad" ships according to the IMO's most current standards for ship maneuverability. Subsequently, their course keeping ability in restricted area are studied in calm seas, shallow water, and under wind and current conditions. The simulation and validation work are done on ESSO OSAKA 278,000DWT Tanker, a well tested ship for regular maneuvering test in past few years. Good agreement has been obtained between results of simulation and sea trial. Since a large portion of disasters happened around coastal areas in the past few years, this Tanker's performance around Vancouver coast is simulated. Moreover, it is studied for the entrance in the Vancouver Harbor under wind and current conditions. The range of current and wind speeds for "successful" operation is then established. The effect of escort tugs on such an operation is also quantified. This thesis shows that a performance improvement index can be assigned to an escort tug for a given assignment. A detailed analysis and comparison with available experimental results are provided.

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