巡視船の低速航行時,惰航時および後進時の操縦性に関する模型実験

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The good manoeuvrability is claimed rather when the ship is advancing with slow speed or with varying her speed as she enters into or comes out of the harbour, than when she is advancing at the service speed in the open sea. At present, however, the researches are carried out mainly concerning the ship at service speed or rather at high speed, and very few are known on the character of ship manoeuvrability at low speed or when the screw is stopped or turned astern. It is pertinent that the ITTC adopted the proposal made by one of the authors, and recommended the promotion of the study of these characters. In order to give a start to the investigations of these characters, the authors performed a series of experiments using a radio-controlled free running 3.8m model of patrol ship type. The unstationary or transient condition of the ship motion was replaced by the sequence of five quasi-stationary stages as follows, and the manoeuvrability of the ship was investigated at each stage. (1) The ship is advancing at slow speed with the screw turning ahead. (2) The screw is stopped to turn, but the ship is still advancing with inertia. (3) The screw starts to turn reversely (astern), but the ship is still advancing ahead with inertia. (4) The ship speed becomes zero by screw turning astern. (5) The ship is going astern with the screw turning astern. In order to realize these stages stationary, the thrust was given by an air propeller equipped on the deck near the pivotting point of the model, besides the water screw. The results obtained are as follows: (1) The manoeuvrability of ship at low speed is almost the same with that of the ship at moderate speed as far as the screw is turning ahead. (2) When the screw stops to turn while the ship is advancing ahead, the course keeping quality and the turning quality becomes poor drastically, because of the lack of the propeller slip stream to the rudder and at this model, without increasing the rudder area and skeg, it is hard to keep her course. (3) When the screw turns astern, the screw race gives a strong turning moment to the hull to one side, (the moment to swing the stern to the left for the ship with right turning screw) that is proportional to the square of the number of revolution regardless the advance speed. The rudder force is rather small compared with this, and as the results, the controlable range becomes very narrow when the screw turns astern. When the model goes astern even by the helm hard over to starboard, the model keeps to turn to the port, and can not be put under control.
独立行政法人海上技術安全研究所の論文
1964-07-30

巡視船の低速航行時,惰航時および後進時の操縦性に関する模型実験

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