Improved US-Model and Its Application for Existence of Small Obstacles

Abstract

Unsafe ship-handling models (US-model) are used to evaluate the potential risk for marine accidents. This article reports on a study undertaken to improve the conventional US-model, which tend to have errors in discrete processing when evaluating small obstacles such as buoys or bridge pier. In the modified version, the authors incorporate the disintegration value to be able to judge about the progress of continuous time and accommodate to the occurrence of unsafe situations such as the bridge pier or buoy. In the ship-handling simulator, the authors compared an output result by conventional US-model and by the improved US-model when the size of the pier diameter was changed. Results showed that if the obstacle became less than 80 meters, the improved model was significantly better than the conventional model.