可変ピツチ推進器船の操縦性について-II(日本航海学会第33回講演会)

Abstract

In general, the effect of steering on the motion of the ship is of complexity when she goes either ahead by her inertia or astern by the propeller thrust. From navigator's standpoint, the author conducted a series of field experiments on the motion of the ship equipped with the variable pitch propeller, in an attempt to clarify the effect of the pitch angle on the transfer/advance ratio and some other performance of the ship in such a state as mentioned above. And the following tendencies were found out: 1. The turning ability of the ship going ahead by her inertia depended on the pitch angle of the propeller regardless of the turning direction or of the rudder angle: The ability is the better when the pitch angle is the larger. 2. The ship going ahead by her inertia represented at 8 to 30 percent decrease from that by propeller thrust, in respect of the ratio, T/A, at 45°to 90°of turning. 3. When the ship goes ahead by her inertia, the propeller of the smaller pitch angle acted the more efficiently as the brake on the distance of advance of the ship along her track. 4. It should be paid special attention to the fact that the ship with variable pitch propeller showed the inverse relation to that with fixed pitch one when they go astern by propeller thrust, in respect of the difficulty in turning due to the difference in the direction: namely, by the starboard steering, it is easy to make her head turning leftside along the same track regardless of the rudder angle. On the other hand, it was possible to make her head turning rightside when the inertia before steering or external forces were favorable to make her so ; otherwise, however large the rudder angle may be, it ended in scarecely no effect.