著者

平賀 譲

出版者

公益社団法人日本船舶海洋工学会

雑誌

造船協會會報 (ISSN:05148499)

巻号頁・発行日

no.40, pp.209-228, 1927-03-15

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The Navy Experimental Tank was destroyed by the earthquake, 1923. The building of new large tank is now going on, but a few years more will be required for completion. So that as a means of the exigency, following an example of Viscount Tokugawa's small tank (25'×3'×2')in his residence for his own experimental work, a small tank (100'×6'×4') has been constructed, provided with the carriage, dynamometer &c. all in the principle of Froude's Tank. In spite of the small value of VL, the measured resistances of 4 feet and 5 feet ship models were found very steady and accurate. In comparing with the results of the Mitsubishi Tank and those of the late navy tank for the same models or similar models applying the Froude's law of friction, the new small tank gave pleasingly good results. The author from his own experience on the design of ships emphasizes an advantage of providing such a tank in a shipyard for the personal guidance of its naval architects, although he, by no means, entertains an idea that small tank shall have the same reliability and accuracy of a large one. It is interesting however that there are certain unique advantages on the side of a small tank, and the experiments to utilize these advantages have been planned and some of them already undertaken, such as the investigations of ships resistance on (a) the effect of the temperature or viscosity to throw some light on the law of friction by simply beating or cooling water in the tank, (b) the effect of the density by easily changing the quality of water, (c) the effect of the depth and width of water by means of simply lowering or raising the dynamometer and a part of the carriage and providing false sides to the tank, all these will be immensely expensive to do for large tanks if not impossible.