Improvement of Prediction of Maneuvering Performance in Shallow Water

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Accurate prediction of manoeuvering motions is essential requirement for enhancing the navigation safety of ships. The usefulness of numerical simulation of maneuvering performance in deep water has been fully established for the case where a ship travels at a moderate forward speed. On the contrary, more efforts are necessary to clarify the hydrodynamic aspects relating to maneuvering motions in shallow water and to validate the mathematical model developed to describe the hydrodynamic forces on a ship traveling in shallow water.In the present research, main emphasis is placed on the following two items ;(1) development of mathematical models for hydro- dynamic forces acting on a ship traveling at a low speed and in shallow water. Especially, development of mathematical models useful even when a ship has excessive sway velocity and/or yaw angular velocity.(2) Examination of usefulness of numerical simulation of stopping maneuvers of ships with reverse rotation of propellers.Concerning the first item, an extensive amount of captive model tests were carried out, and then a mathematical model was proposed. Regarding the second item, results of numerical simulation of stopping maneuvers were compared with the results of free-running model tests. As a result, it was confirmed that the macroscopic qualities of stopping maneuvers, i. e. track reach, head reach, side reach, stopping time and stopping angle could be predicted by numerical simulations with enough accuracy for practical purpose.