Sea Passage Scenario Simulation for Ship System Performance Evaluation
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- Institutt for marin teknikk 
This thesis addresses evaluation of ship system operational performance exposed to ocean waves for providing enhanced evaluation capabilities in the transition towards environmentally friendly shipping. It proposes and discusses simulation techniques for replicating operational behavior as a function of design capabilities, challenges inherent to operation and environment, and available measures and knowledge affecting operational conduct of given designs. The overall research objective is to contribute to the transition towards environmentally friendly shipping by improving system performance evaluation capabilities in the early design stage. Application of simulation as a tool for measuring system performance variables, emerging as a consequence of system-environment interaction in relevant scenarios, is considered as a technique for reducing technical risks associated with installation of new technology with limited track record. The research is published in five papers, each presenting and discussing individual contributions to the research objective. Article 1 presents a simulation-based approach to operability assessment of ships performing non-transport operations interrupted by weather windows exceeding design capabilities, and compares the approach to static analysis methods. Recognizing the importance of replicating long-term wave environment variability for predictions, three stochastic models are presented and evaluated for application in simulation-based design in Article 2. Work towards understanding and replicating sea passage scenarios starts in Article 3, where results from a discrete-event simulator is compared to on-board performance measurement system data from a real ship in operation. Improving simulator validity and functionality, Article 4 presents an optimization for simulation technique, providing an interface between the operational and physical domain and testing of sea passage scenarios. The importance of this functionality as well as static analysis comparison is addressed in Article 5. This research project, through combinations and applications of knowledge and methods in novel ways, exposes the importance of scenario control and delivers techniques for implementing and testing new technology in operational scenarios during design of ships. Four key contributions are identified from the Thesis. First, an extension of ship level simulation to include logistical factors is presented, expanding the system boundaries by means of a virtual captain interface. Second, insight into the importance of scenario control for system performance variables prediction. Third, an optimization for simulation technique for application in virtual testing of ships using simulation during design. Fourth, case studies documented in the papers demonstrating potential added-value of scenario simulation-based interpretation of ship design. Scenario simulation is of instrumental value in the transition towards environmentally friendly shipping as it facilitates reduction of technical risk associated with novel systems through virtual testing. The work constitute a contribution towards achieving trustworthy simulation predictions of system performance variables. The need for further work addressing ship characteristics in a seaway is recognized, where in particular wave added resistance and effects on propulsion systems represents important topics with value to the presented research.