Anti-pitching Tankの理論的ならびに実験的研究

抄録

Hitherto, many methods of reducing the rolling motion of ships, have been studied : the bilge keel, anti-rolling tank, gyrostabilizer etc. may be cited as examples. But there is almost no study available regarding the pitching of ships. This paper proposes to deal theoretically and experimentally with the pitching motion of ships with tanks which have a close resemblance to the anti-rolling tank of Foerster's open type. According to the paper under the title of "On the Design of Anti-rolling Tanks" presented by Prof. Y. Watanabe, the equation of the pitching motion of ships with tanks may easily be found. The general solution of this equation consists of two parts which are the solutions for free and forced motions. The consideration to the free pitching motion is not very important because it vanishes soon. Accordingly, the forced pitching one only will be dealt with in this present paper. From the calculation of the pitching amplitudes, it is reasonably believed that an anti-pitcing tnak has the ability of reducing the maximum amplitude by about 20%. In order to confirm the accuracy of the result of calculation, further experiments have been carried out by using a ship model equipped with anti-pitching tanks occupying 15% of the length between the perpendiculars, at the bow and stern of the ship model. As a result, it has become evident that about 20% reduction in the pitching amplitude of a ship with the tanks is possible to obtain when the surrounding related condition is at its best.