| Summary: | The energy consumption and the Greenhouse Gas (GHG) emissions from shipping field are vast and very important which cannot be ignored for both economic and environmental reasons. Improving energy efficiency of the ship through the technical and operational means has become a pressing issue faced by the shipping industry. In this context, ship weather routing technique, as one of the effective energy efficiency improvement methods has attracted more and more interests from technical staff. A ship weather routing system towards energy efficiency is developed in this study. This system consists of six modules which are ship performance calculation module, grids system design module, weather data module, ship safety module, weather routing module and post-processing module. These modules basically cover the essential elements of a ship weather routing system. Among them, the calculation methods of various ship performances are utilised in ship performance module; The design principle of grids system and an intelligent land avoidance function are developed in grids system design module; The acquisition and decoding of weather data files are introduced in weather data module; A ship safety guidance is selected and followed in ship safety module; A combination of global and local optimization algorithm is adopted in weather routing module; A backward iteration algorithm is developed and the visualization of result routes is implemented in the post-processing module. The role of each module and the data transfer relationship between these modules are described in detail. Next, seven effective methods are introduced to upgrade the system. The role of each module and the data transfer relationship between these modules are described in detail. Next, seven effective methods are introduced to upgrade the system. These methods which can greatly improve the working efficiency of the system are respectively: create ship performance database, redefine ship travel principle and adjust the grids system scale, merge ship safety module to ship performance prediction module, delete results in every waypoint which cannot meet the time schedule, set the speed control parameter, delete results in every waypoint which cannot meet expected fuel consumption and optimise programming codes. With these methods introduced, the structure and operation logic of the system also becomes more effective. A series of representative case studies are carried out to verify the proposed methodology and the tool. Finally, the approach is implemented on a container ship in both purely motorised and Flettner rotor assisted propulsion conditions, to see the energy efficiency gained through Flettner rotor technology. Case studies in various shipping routes, departure times and ship speeds are carried out based on this system and finally a framework for assessing the performance of wind assist technology is proposed. The proposed weather routing system has significant practical application and can provide an effective reference for related research in the shipping industry.
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