The corrosion behavior of such materials composing a ship as Ti-6Al-4V for propeller shaft, an Al-Mg alloy for body and Al-bronze for propeller are investigated. A kind of Al-Zn-Ga alloy is found out to be a good sacrificial anode. The good properties are proved by a corrosion test in real sea water for a year, too.
A crevice corrosion test is carried out to check the corrosion behavior of propeller shaft coupled with a kind of stainless steel, and proved to be no problem.
The effects of hydrogen absorption on the mechanical properties of Ti-6Al-4V is examined, and it shows no change up to about 1000ppm in the case of specimen absorbing it uniformly.
The size effect of fatigue strength of Ti-6Al-4V is proved to be no more than that of steels.
The propagation rate of fatigue crack in synthetic sea water is proved to be equal to that in air, if Ti-6Al-4V is applied under cathodic protection.

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On the former report, loss coefficients of various type valves of 200 mm bore were compared and discussed. In the case of butterfly valve, loss coefficients are mainly affected by valve bore, disc shape and disc thickness ratio for valve bore. In this report, the effects of disc thickness and disc shape on the loss coefficients for 200 mm bore butterfly valves are investigated and the effect of opening ratio on the coefficient at partial open and cavitation points are discussed. At valve full open, the coefficients increase according to the increase of disc thickness, but change is irregular by the shape effect. As per disc shape, the coefficient with spindle shape disc is 40% smaller than that with projection type disc having same thickness. At partial open, the coefficients are put in order by the opening ratio.

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船尾管シール装置において, 船外への漏油を防止するためには従来の発想を根本的に転換し, 船尾管内油圧を常時海水圧より低く設定する方式が有効である.この方式に対して海水より比重の高い潤滑油 (高比重油) を用いることにすれば, 万一船尾管後部シール装置に海水が浸入した場合, この海水を高比重油との比重差を利用して自動的に分離し, 船内へ回収することができる.
本報では, 高比重油を船尾管の潤滑システムに使用する際に必要な基本的特性として, 高比重油の潤滑性・抗乳化性・加水分解安定性及びシールリングとの適性について調査した.また, 船尾管シール装置内へ浸入した海水を分離・回収する作動試験を実施した.
その結果, 高比重油を用いた船尾管の潤滑システムが十分に実用可能であることを確認した.

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The temperature rise characteristics of the induction motor can be calculated, if the copper loss, the iron loss and thermal model constants are given. Thermal model constants include thermal conductivity from coil to core (λ_cf), heat transfer coefficient from coil to air (λ_ca), heat transfer coefficient from core to air (λ_fa ), λ_a ≡λ_cf+λ_ca, λ_b≡λ_cf+λ_fa, thermal unit capacities of coils (H_c) and iron cores (H_f) . The time constant of temperature rise of the induction motor increases with the load increasing. In this case, values of H_c and H_f are made to hold constant and λ_a, λ_b and λ_cf decrease as the load increases. In this paper, the temperature rise characteristics of the continuous operation, intermittent operation and the repeated on-off operation are analyzed and calculated by using the afore mentioned method.

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This report describes investigation of tow-boat traulers in the east china sea with medium-speed diesel engines burning blended fuel of Bunker C and marine diesel oil to save the fuel cost.
Performance and maintenance of engines were investigated and compared economical efficiency of blended fuel with marine diesel oil on fishing boat engine.
Running the engines in its standard marine diesel oil form except for fuel heater and Stellite-face exhaust valves on blended fuel proved to increase exhaust temperature and specific fuel consumption. Maintenance interval of valve, injector and turbo-charger reduce about a half period in comparison with burning marine diesel oil.
However satisfactory results was obtained on newly-built fishing boat with new engine which had sufficiently considered the counterplan for low quality fuel.

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