Study on Safety of Ship Navigation in Narrow Waterway

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It is well known that hydrodynamic interaction forces between ships or between ship and bank wall or pier have much influence on characteristics of ship manoeuvrability. It is important to know the characteristics of these interaction forces to insure safety of sailing ships. Then we developed theoretical prediction method for the hydrodynamic interaction forces based on the slender body theory and carried out numerical simulation of manoeuvring motion of ships sailing in the proximity of pier. According to the results of numerical calculation, there is a danger that the ship will collide with the pier if the lateral ship distance is less than 0.7 L.We also developed prediction method for cross flow drag acting on a ship hull based on the vortex shedding model because component of cross flow drag dominates the hydrodynamic force acting on ship hull when ship is moving with large drift angle at low speed. It is shown that longitudinal distribution of the cross flow drag along the ship length can be predicted with comparatively comparatively high accuracy using the presented prediction method.Furthermore we presented collision avoidance system using the predicted hydrodynamic forces and investigated effectiveness of the system by numerical simulation considering human factor.