船の進行方向に対する風の相対角と相対風速,及び波の柏対角と波高が見掛けのプロペラのスリップに及ぼす影響について重回帰分析して,回帰式(5%有意)を得た。概要は以降のとおりである。1)プロペラのスリップには,風の相対角が最も影響し,次に相対風速であった。2)船速に対しては,風の相対角が最も影響し,次に風速,波高,波の相対角及び潮流の相対角であった。3)主機関の燃料油消費量に対しては,相対風速が最も影響し,次に波高,波の相対角であった。

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小型漁船「サバニ」はカヌーに船型及び船体構造がよく似ている。そこで,サバこの耐航性について,実船実験を行い検討した。横揺れ運動は横波及び斜め追い波状態で,縦揺れ運動は向い波状態で大きく,横揺れは縦揺れの3倍であった。従って,荒天時には向い波状態で航行するのがよい。横波状態の横揺れに関して,波と横揺れのスペクトルの卓越範囲は2～6秒,ピーク値は3～4秒で両者はよく一致している。周期1～4秒の範囲でコヒーレンシーは0.5,相対誤差は0.5以下であり,周波数応答答関数の推定精度は良好と考える。両者の関係は0.44deg/cmである。向い波状態の縦揺れに関して,波と縦揺れの両スペクトルのピーク値は1.5秒,コヒーレンシーは0.9以上,相対誤差は0.1以下である。また,両者の関係は0.07deg/cmである。サバ二はトリム零で航走するときが運動量が少なく,安全性から見て最も良い状態であると考える。従って,漁具や漁獲物の積み付けには十分注意し,トリム零を保つよう心がけることが大切である。

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A controlable pitch propeller (C.P.P.) on the fishing boat produces not only a reduction of the fuel consumption of the driving diesel engine but an increase of towing power compared with a fixed pitch propeller. However, an engine operated under inadequate C.P.P. management can not fully display the expected effects. Thus, experiments on the fuel consumption of main engine were conducted to evaluate the operation of C.P.P. blade angle. The results showed that the minimum fuel consumption of main engine operated under the generating power greater than 50% were obtained by the blade angle at 21 deg. with the revolution control, and that under the generating power lower than 50% were obtained by setting the operation point of main engine at the right side of maximum propulsion efficiency curve on the performance chart which showed the output of main engine in abscissa and the number of shaft revolution in ordinate. From the results, it can be also concluded that a reduction of deposit which is produced by the reduction of thermal stress, by improvement in combustion, by the prevention of deterioration of the lubricating oil has good effects on maintenance and durability of main engine.

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The studies were undertaken to accumulate fundamental data for artificial formation of seaweed beds in the areas of decadent seashore condition. The investigation was firstly made of the role of repellence against abalone Hal紡is discus hannaj of benthic animal using malic and citric acids and their carboxylates, and secondly was Carried out in regards to the effect of these substances on the growth of Sargassum horneri. Among the repellence effect of the substances for abalone, the effect of malic acid was largest at low concentraions, followed by those of citric acid, malate and citrate. The substances were also confirmed to promote the growth of germlings and fronds of S. horneri in the laboratory culture. Using malic and citric acids which elicited repellence effect at low concentrations against abalone, the relationship between each of two substances and the growth of S. hoγneγi was observed in the field. The method was carried out by setting up concrete blocks (tetrapod type, about 30 cm in heicht) at 2 m under sea surface. The blocks were coated with synthetic resin (aminoethylated acrylic resin) containing malic and citric acids and rolled twine attached with seedling of S. horneri. By the observations of growth of S. horneri after 8 months, it was found that the growth was remarkable and many fronds survived on the blocks in the case of using malic acid. The results showed that malic acid was nutrient element for growth of S. hornerj and prevented to be disppeared by grazing of benthic animal for frond of one. As mentioned above, it is much expected that the use of malic acid practica11y produces beneficial effect in the formation of artificial seaweed beds.

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