| Résumé | Optimizing the performance of an escort tug is an important part of the design process, but the impact of tug performance on total system performance is the critical issue. Whilst tug performance can be predicted with model experiments, this is an impractical method for evaluating the combined tug-towrope-tanker system. Numerical simulation of the total system is a much more practical option, since numerical maneuvering models for ships are well established and can easily include the predicted trajectory of the tanker under the action of a force generated by the tug. The challenging part of the simulation is providing a realistic estimate of the tug performance. IMD has developed a hybrid modeling process that combines captive model experiments for obtaining hydrodynamic coefficients of the tug with numerical simulation of the complete system. This paper describes the development of the method and presents some results to demonstrate trends in system performance with design variables, such as location of the towing point. It also discusses some operating practices and the associated safety considerations. |
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