オオガタ カイリュウ スイソウ ニヨル 1000 トンガタ ギョセン ノ センケイ シケン ケッカ ニツイテ

Experiments on a model ship have not so frequently performed in a circulating tank, because of an unreasonable belief that the results so obtained are dubious in the reliability. The experimental evidence presented in this and previous paper (1958a,b) indicates that a circulating tank is not inferior to a towing tank when adequate corrections are applied. When the ship speed is as low as less than 12 knots, that is, in the case of the predominance of frictional resistance, the total resistance give a larger value than obtainable in a towing tank, working on a model of a large fishing vessel. This fact is due to an increase of frictional resistance in the turbulent flow. The modifications of the correction value for a towing tank test (ΔCf=0.0004 or ε=1.19), which should be applied for a circulating tank, are shown in Fig.3. When the ship speed is over 12 knots, i.e. in case of the predominance of wave-making resistance, numerical value of the total resistance, and consequently D.H.P., approaches to that of the actual ship. Comparing these results with those of a small vessel presented in the previous paper, the influence of the electrically welded structure of the hull of the large vessel can be seen at low ship speed