逆スパイラル試験の中・小型船への適用について

概要

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For the purpose of ascertaining characteristics of course stability, the spiral test originated by J. Dieudonne [1] has frequently been used. Main defects of this test are: (1) it requires broad sea room, (2) it takes very long time, and (3) it has to be performed only under the limited weather and sea conditions. On the other hand, ship forms are continuously becoming more and more huge and gross, and course instability has become an urgent problem in the field of naval architecture. Few years ago, Mogens Bech proposed a testing method using the rate gyro to obtain the relation between r and δ in the form of δ=δ(r). This method is called reversed spiral test, and with this new technique, data connected with course stability for giant ships have been accumulating. The authors tried to apply Bech's method to three smaller vessels, namely 3463 G.T. (A), 1643 G.T. (B), and 331 G.T. (C), and to ascertain whether or not the merits of the new method are valid for these ships. Our conclusions are as follows ; (1) Sea room and duration for a test required did not change remarkably with ship A and ship B, (2) Our attempt to obtain the detailed characteristics of the inside of hysteresis loop (ship C is known as unstable) was fruitless. (3) To gain the general view of r-δ curve, Bech's method is suitable for these ships.
社団法人日本航海学会の論文
1972-12-20