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Article type: Cover
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Published: June 30, 1971
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Article type: Cover
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Published: June 30, 1971
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Article type: Appendix
Pages
_i_-_iii_
Published: June 30, 1971
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[in Japanese]
Article type: Article
Pages
1-2
Published: June 30, 1971
Released on J-STAGE: March 30, 2018
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Shoichi NAKAMURA, Keinosuke HONDA
Article type: Article
Pages
3-12
Published: June 30, 1971
Released on J-STAGE: March 30, 2018
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Main object of this investigation is to find a prototype of ship's anchor which has larger holding power and dragging stability by systematic model tests. For the comparision of holding power characteristics, coefficients λ, α, μ, and etc. were used, where the coefficient of holding power λ is a ratio of maximum dragging pull at zero speed in pull-speed curve to weight of anchor, the coefficient of dragging stability α is a ratio of the area enclosed with the measured curve of holding power vs. dragging distance to the area multiplied the maximum dragging pull by dragging distance and the coefficient of holding characteristics is μ is λα. From the results of experiments in sand bottoms, the authors obtained a new prototype of ship's anchor, KS-7 type, having superior holding characteristics. Futhermore, the effect of shape factors of anchor on the holding characteristics are investigated, and the results are as follows : 1) The holding power is more affected by the vertical projected area of fluke (A_<fy>) than the vertical projected area of anchor-head (A_y). 2) As to the effect of shape factors on the dragging stability, the most important factor is b/h, the next is e/b, and e/h has almost no effect, where b is the width of crown-bed, h is the length of fluke, and e is the gap between the tip of both flukes. 3) It seems that the anchor having large holding power is not good in the dragging stability, and that the relation between μ and A_y/A_<fy> is also similar.
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Michimasa ENDO, Kimio YOKOTA, Naochika NANBA, Hirofumi SEKIGAWA, Takay ...
Article type: Article
Pages
13-22
Published: June 30, 1971
Released on J-STAGE: March 30, 2018
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There is an ever increasing need for man to descend deeper in the ocean, for there are sources of food, minerals, oil and etc. and the investigation to realize the efficient submersible that can descend to the depths of 6,000m has been conducted in various fields of technology. One of the major factors limiting the rapid exploration and exploitation of the undersea has been the materials problem, especially the buoyancy material to achieve neutral buoyancy at great depth. As the buoyancy material, gasoline was used in "Trieste" and "Archimedes". But it has several inherent disadvantages such as high compressibility, flammability and high density and it is a key factor in building more small and maneuverable deep submersibles to develop a more efficient floatation system. For this purpose, syntactic foam, hollow glass microsphere embeded in resin matrix, is developed. This material has great advantages compared to the other candidates and is now produced for the submersibles of operating depth 2,000 to 3,000m, but not for 6,000m submersible use. We have been engaged in the development of higher strength and lower density syntactic foam available for 6,000m submersible and some experiments were done to have more information about deep sea application. As the results, we reached to the conclusion that we can produce the syntactic foam suitable for 6,000m submersible and not only for deep submersible application, foams of various strength and properties can be produced according to it's operating depth. Succeeding to the first stage investigation reported here, we are now engaged in the farther development of this material to ascertain it's properties. This will be reported on another occasion.
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Hiroshi OKAMOTO, Akira TANAKA, Kazuo NOZAWA, Yasuo SAITO
Article type: Article
Pages
23-33
Published: June 30, 1971
Released on J-STAGE: March 30, 2018
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Recently KHI built three kinds of ships equipped with controllable pitch propeller (CPP). They are a reefer, a container and an ore/oil tanker and all of them are higher-powered ships in comparison with those built before. As speed and size of ships increase, necessity of better stopping abilities has been increased. Investigations on the stopping abilities of ships with fixed pitch propeller (EPP) have been reported in detail by many researchers, but those on CPP ships are very rare. As the first step of the investigation on the stopping abilities of ships equipped with CPP, the authors report on crash astern test results, measured at sea trial test of above mentioned ships and compare with those of FPP ships. Furthermore they show the results of computation about transient phenomena in case of CPP ships by using one dimensional equation of motion and compare them with sea trial results.
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Toshio HISHIDA
Article type: Article
Pages
35-44
Published: June 30, 1971
Released on J-STAGE: March 30, 2018
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The formation mechanism of the initial wind waves is discussed from the following point of view referred to the process of wave formation in the experimental tank: Free oscillation of a water surface is caused by a moment of blowing wind, which is sorted out into series of group waves. The initial wind waves are the group waves magnified with the energy that each constituent wave absorbs from the current of wind. The magnification takes form of a negatative resistance to the wave motion.
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Masaki GANNO, Matao TAKAGI
Article type: Article
Pages
45-54
Published: June 30, 1971
Released on J-STAGE: March 30, 2018
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In this report the authors carried out theoretical investigation into the hydrodynamic forces related to ship motions, the results of which are as follows: 1) The validity of Watanabe's approximate method, which is used for the calculation of the wave forces in Iongitudinal ship motions, was investigated. As a result, we can safely conclude that the method yields preferable results so far as it is used for the calculation of ship motions by strip method. 2) The asymptotic value of A^^-_H (the ratio of the amplitude of the progressive wave induced by the heaving of a cylinder with Lewis form section to that of the heaving) was shown to be [numerical formula] when ξd=κd (κ=wave number, d=draft) tends to ∞, where a_1 and a_3 are the coefficients of Lewis form. 3) The relations among the coefficients of hydrodynamic forces in transverse ship motions were investigated. Putting the damping coefficients due to wave Ns: sway-sway, N_R: roll-roll N_<SR>: sway-roll, l_W=N_<SR%gt;/N_S and the wave forces F_e: sway force, M_e: roll moment, the authors proved the following relations: l_w^2=(N_R)/(N_S) and M_e=l_wF_e.
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Kohei MATSUMOTO, Hiroaki KADOH
Article type: Article
Pages
55-65
Published: June 30, 1971
Released on J-STAGE: March 30, 2018
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In calculating natural frequencies of a ship, the ship's hull is generally regarded as a free-free beam with variable cross sections. Although several calculation methods by the use of digital computer are available for such a stepped beam analysis, there are few investigations made into the accuracy of those methods. In this report, three methods, Myklestad-Prohl Method, Transfer Matrix Method and Finite Element Method, are chosen as representative methods to analyse ship vibration, and their applicability and accuracy due to the effect of beam properties are investigated. Morever mutual relationship among those methods and the results of their applications to actual ships are discussed. From these studies the following conclusions have been obtained. (1) As to the accuracy of the calculation methods when they are used for calculation of natural frequencies of a ship up to 8th mode, the results are as follows: (a) Transfer Matrix Method: It is possible to keep the error less than 1 per cent by taking 6 terms of Taylor's expansion of transfer matrix when the ship is divided into 20 segments and 4 terms when 40 segments. (b) Finite Element Method: The accuracy is about the same with the approximation of taking 8 terms in Transfer Matrix Method when bending displacement only is considered and 4∼5 terms when both bending and shear are considered. (2) For practical purpose, the above-mentioned two methods are applicable to the calculation of natural frequencies up to 8th mode of vertical vibration with reasonable accuracy. (3) The calculated natural frequencies by digital computer are closely agreed with experimental results in the lower vibration modes. But in higher modes the calculated frequencies are tending to be higher than those measured as ship sizes grow.
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[in Japanese], [in Japanese], [in Japanese]
Article type: Article
Pages
67-76
Published: June 30, 1971
Released on J-STAGE: March 30, 2018
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[in Japanese]
Article type: Article
Pages
77-81
Published: June 30, 1971
Released on J-STAGE: March 30, 2018
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Article type: Appendix
Pages
82-
Published: June 30, 1971
Released on J-STAGE: March 30, 2018
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[in Japanese]
Article type: Article
Pages
82-
Published: June 30, 1971
Released on J-STAGE: March 30, 2018
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Article type: Appendix
Pages
82-
Published: June 30, 1971
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Article type: Appendix
Pages
82-
Published: June 30, 1971
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Article type: Appendix
Pages
83-86
Published: June 30, 1971
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Article type: Appendix
Pages
App1-
Published: June 30, 1971
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Article type: Appendix
Pages
App2-
Published: June 30, 1971
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Article type: Appendix
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App3-
Published: June 30, 1971
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Article type: Appendix
Pages
App4-
Published: June 30, 1971
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Article type: Cover
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Published: June 30, 1971
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