Abstract
The size of the ship's turning circle is influenced by various factors, such as block coefficient, underwater side shape, rudder area ratio, draft, trim and Froude's number. Most of them are already fixed on departure from a port. However, the ship's speed and the rudder angle are controllable factors which operations are able to change optionally during sailing. The DGPS measured the turning circles according to the ship's speed and the rudder angle. The maximum advances by slow and full ahead were 302m and 311m, and the maximum transfers were 460m and 452m, respectively. There occurs almost no difference in size of the turning circle by variation of the ship's speeds. When the rudder angles were changed to $10^{\circ}$, $20^{\circ}$ and $30^{\circ}$, the maximum advances were 447m, 271m and 202m, and then also the maximum transfers 657m, 426m and 285m, respectively. The diameter of the tuning circle was decreased exponentially when the rudder angle was increased. The maneuverability was better when the direction of turning and propulsion of propeller are in the opposite direction rather than in the same one togetherm. The distance of the maximum transfer was always bigger than that of the maximum advance.
