Study On The Leeway And Drift Angle Of The Ship

Based on the ship maneuvering mathematical model on water surface, the thesis built up a ship maneuvering mathematical model. The model took the effect of shallow water and the effect of interference forces and moments by winds and sea currents during maneuvering into account. Moreover, this article has made a quantitative research of ship's leeway and drift angles in different wind and currents after maneuvering.When building up the mathematical model, based on MMG modeling thought the following factors have been considered: the forces and moments acted on ship's hull, propeller, rudder and interrelationships; the shallow water effect; the interference forces and moments of winds and currents. The paper applied the the Runge-Kutta calculating method to calculate the equation of maneuvering mathematical model, and the ship maneuvering simulation researches are carried out by use of the MATLAB's Simulink Toolbox in order to get the leeway and drift angle in different wind and currents when maneuvering.The study has obtained the following conclusion: When the current cross flows, drift is mainly related to speed and has nothing to do with ship's condition, depth and Category. The higher the ship speed the greater the ship drift. On the other hand ,the leeway received various impact, like ship's speed, ship's types and ship's loading conditions. Based on the drift and leeway dates, we present the drift and leeway angles of two ships when maneuvering in cross wind and cross current.The research provides with the reference for the pilots and captains on safe control of the vessel berthing or unberthing maneuvering and narrow channel. It also brings forward a new method in simulating ship maneuvering capability in wind and current.