可変ピツチプロペラを装備した曳船「吉野丸」の曳航試験について

抄録

In the service condition of a tug boat, the propeller must operate in various ship speeds, that is, in the conditions of ship moored at a shore, towing other ship and running alone. Therefore, the propeller of tug boat must be so designed that it develops full thrust force extending over a wide scope of ship speed. In the case the fixed pitch propeller is equipped, it is difficult to develop full power of the engine in whole range of ship speed on account of the restriction imposed by revolution and torque of the engine. When a controllable pitch propeller is used, however, the engine can develop its full power independently of the ship speed. From the above reason, some of shipbuilders in Japan equipped with controllable pitch propellers having powerfull towing pull and excellent maneuvering character in the last several years, in connection with the tendency to construct large size ships. In this paper, the results of bollard pull trial, towing pull trial and speed trial at free running of the tug boat "YOSHINO MARU" equipped with two controllable pitch propellers are described.