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Article type: Cover
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Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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Article type: Cover
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Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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Masao KINOSHITA, Hiroshi MAKIMOTO
Article type: Article
Pages
1-6
Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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Many kinds of marine cargo blocks have been used as the cargo handling equipments of vessels, but it has been found very difficult to estimate their correct efficiency at the designing stage, mainly for lack of available experimental data on them. In order to obtain their data the present authors have carried out several experimental investigations on some kinds of cargo blocks, and obtained the follwing results. (a) For steel cargo blocks: 1) The cargo blocks improves slightly in their efficiency with the increase of the lifting load. 2) The efficiency did not vary practically even when alterations were made in the angle of the wire ropes. 3) As far as the present experiment is concerned, slight changes in the efficiency take place depending on the size of the sheave diameter of the cargo block. 4) In the case of thec argo block provided with a bush and without snatch blocks, the efficiency was in the range of 0.89-0.93 or so, but cargo blocks provided with roller bearings showed values about 5% better. 5) Among the cargo blocks provided with roller bearings, the double row type was slightly better than the single row type. 6) In the case of the cargo blocks provided with a bush and without snatch blocks, the friction coefficient μ between the sheave and the shaft of cargo block was found to be in the range of 0.21-0.36, which are fairly large values as compared with the friction coefficient generally assumed. This is, presumably, the reason why the efficiency of the cargo block showed lower values in the present experiment than those employed empirically heretofore. With respect to the cargo block provided with roller bearing, the friction coefficient μ was found to be in the range 0.05-0.15. (b) The efficiency of wooden cargo blocks lays in 0.90-0.96.
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Shiro WATANABE, Saburo YASUI, Hiroshi OKAMOTO, Hiroshi SHIMIZU, Kazuya ...
Article type: Article
Pages
7-13
Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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This report outlines the result of our investigation on the typical singing of propeller, conducted on a ship recently built in our yard. This investigation confirmed Dr. Kito's theory that the singing phenomenon of propeller is the coincidence of frequency of the exciting force to the natural frequency of the propeller blade, which is periodically excited by the Karman Vortices induced from the trailing edge. Singing phenomena measured on our ship were as follows. 1. Singing appeared at about 100 r/m and disappeared at 210 r/m, and no singing above this revolution. 2. Peak frequency of the singing was 655 c/sec, which was independent to propeller revolution. 3. 655 c/sec was found to be one of the natural frequencies of the propeller blade in water. 4. By, so-called, Karman Vortex theory, it was calculated that the effective edge thickness of 2.3 mmφ constantly causes 655 c/sec at the revolutions between about 100 r/m and 210 r/m. 5. It was found during the docking that the edge was about 2 mmφ. 6. The initially designed edge was 1.0 mmφ. At the sea trial conducted after the correction of the edge to 1.0 mmφ, sinig was completely diminished. 7. As the general conclusion, the edges of small diameter propellers must be more accurately finished.
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Fukuo SHIBATA
Article type: Article
Pages
14-21
Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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A number of vessels with electric propulsion have recently been built in Germany, Britain and several other countries. Electric propulsion systems adopted in these vessels, however, do not largely differ from the ones in the earlier stage. They decidedly use Ward Leonard for D.C. system and either synchronous or asynchronous motor system by speed change for A.C. system. In this treatise, I have introduced a new system of electric propulsion which may be adopted for any kind of vessels, because it is very economic from the point of view of initial cost and fuel consumption, and the speed can be smoothly controlled in wide range.
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Masami HOSONO
Article type: Article
Pages
22-26
Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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Damages of marine motors are influenced by the following factors:- (1) Design, material and construction. (2) Installation and surroundings. (3) Working conditions. (4) Inspection and repairs. Marine motors are generally installed in unfavourable conditions, namely in high temperature, high humidity, heavy vibration and so forth, and liable to suffer damages. The working conditions, investigated on several ships, show that their motors run in moderate loadings. When a damage arises on a motor, we must research and eliminate its cause, and it is necessary to record its details completely for future reference. Damages on insulation and bearings occur more frequently on marine motors than in the case of land motors. Motors for cargo winches and for ventilating fans sustain damage most frequently than for other uses.
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Seikan ISHIGAI, Zyumei KIWAKI, Kiyoshi INOUE
Article type: Article
Pages
27-33
Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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This paper is a report on the further study on the heat transfer and flow of the mixture of steam, condensate and air in a glass tube simulated to the heating coil in the cargo-oil tank of the oil carrier. The inside diameter of the glass tube is 15 mm, which is larger than the inside diameter in the preceding experiment. It was demonstrated that the condensate could be discharged continuously from the outlet only when the supplied steam pressure was in a limited range. If the steam pressure is excessive, steam will blow out sooner or later from the outlet end of the coil. If the steam pressure is insufficient, the condensate hold-up in the heating coil continues to increase and will finally occupy the entire tube. When the heating section of the coil is in a horizontal plane and steam is supplied at the pressure within the above mentioned limits, a strong fluctuation is brought about in the condensate flow. When the heating coil has ups and downs in the heating section, the air and the condensate flow across the ups and downs in a particular way. The result of the experiment indicates that hot-water is a more suitable medium than steam for cargo-oil tank heating.
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Hideo SASAJIMA, Eiichi YOSHIDA
Article type: Article
Pages
34-38
Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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In a previous paper (literature 1) a method of calculation of form drag has been described. As the second report concerning the same problem, the present paper deals with an approximate method of estimation of pressure loss due to viscous effect near body tail. It is much probable that the pressure drag due to the change of ideal pressure distribution resulting from the formation of boundary layer can reach a considerable amount for a full body even without separation. This phenomenon is especially of importance in ship resistance problem. The calculating procedure is as follows. Using the modified Buri's method two independent equations are solved simultaneously and the pressure loss is derived. The discussion about separation point and Reynolds effect is not made. Comparison with the experimental results of Fage et al. shows a fairly good coincidence.
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Masayuki YAMAMOTO
Article type: Article
Pages
39-41
Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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The author has applied the Dr. Nakagawa's theory on non-linear elasticity to thermal stress problem of the body which does not obey Hooke's law such as cast iron. Some examples of Φ function have been tried.
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[in Japanese]
Article type: Article
Pages
42-43
Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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[in Japanese]
Article type: Article
Pages
44-49
Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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[in Japanese]
Article type: Article
Pages
51-56
Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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[in Japanese]
Article type: Article
Pages
57-68
Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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Article type: Appendix
Pages
69-70
Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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Article type: Appendix
Pages
App1-
Published: March 31, 1961
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Article type: Appendix
Pages
App2-
Published: March 31, 1961
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Article type: Appendix
Pages
App3-
Published: March 31, 1961
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Article type: Appendix
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Published: March 31, 1961
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Article type: Appendix
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Published: March 31, 1961
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Article type: Appendix
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Published: March 31, 1961
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Article type: Appendix
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Published: March 31, 1961
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Article type: Appendix
Pages
App8-
Published: March 31, 1961
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Article type: Cover
Pages
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Published: March 31, 1961
Released on J-STAGE: February 24, 2018
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