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Article type: Cover
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Published: December 30, 1977
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Article type: Cover
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Published: December 30, 1977
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Article type: Appendix
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App1-
Published: December 30, 1977
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Tomoo HANAWA
Article type: Article
Pages
1-10
Published: December 30, 1977
Released on J-STAGE: March 30, 2018
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This paper presents a method of designing hull form o ships except low speed full types to reduce the wave-making resistance at the preliminary design stage. The procedure to be taken is as follows. (1) C_p curve of a main hull without bulb is given as a mathematical formula, ψ_1(ζ)=A cos aζ+B cos 2aζ+C, its coefficients are determined by using the chart which are leaded from the result of calculation based on Thin Ship Theory. (2) C_p curve of a bulbous hull is given by deforming Rankine's Ovoid, in proportion to the wave phase lags corresponding with its main hull. (3) A complex body of both main and bulbous hull to obtain the optimum hull form is drawn numerically and geometrically, with taking consideration of the wave-making non-linear phenomenon.
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Kiyoshi HARA
Article type: Article
Pages
11-21
Published: December 30, 1977
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A basic concept for estimating the reliability of collision avoidance maneuver can be derived by applying reliability theory to the relation between collision avoidance maneuver and traffic environment. A Markov reliability model was analytically constructed by making an encounter of two ships on collision course correspond to a failure, an evasive action to a repair and an occurance of collision accident to an absorbing state in terms of reliarbility engineering, respectively. The model was numerically expressed under assumptions based on the traffic survey, the statistical analysis of collision avoidance maneuver at sea and simulated maneuvers by a ship handling simulator. Then the reliability of collision avoidance maneuvers by the model was compared with that based on collision statistics at the Seto Inland Sea over the last five years. They were found to correspond well by the appropriate estimations of parameters in the model. Based on the model it would be capable for us to evaluate how much the components related to collision avoidance maneuver would have an effect on its reliability.
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Seizo MOTORA, Kenichi UEDA, Toshihiko SARUTA, Tsutomu IDA, Tanekazu KU ...
Article type: Article
Pages
23-28
Published: December 30, 1977
Released on J-STAGE: March 30, 2018
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A navigation aids research vessel "Tsushima" of Maritime Safety Agency equiped with an anti-rolling tank has been constructed at Tamano Ship Yard of Mitsui Shipbuilding Co. At the design stage of the ship, performance test of the anti-rolling tank was conducted on a 1/28 scale self-propelled model at the Seakeeping Basin of Tokyo University. In this paper, results of model experiments in irregular seas are reported. In those experiments, the model was encountered with irregular waves which had simulated ITTC spectra for 10 m/sec and 15 m/sec wind speed, and motion of the model was measured by a data recorder. Spectral analysis as well as collation of amplitudes were conducted. Making use of analysed data, the effectiveness of the anti-rolling tank was evaluated by the following formula. Effectiveness = ((σ_φ/σ_w) without - (σ_φ/σ_w) with)/((σ_φ/σ_w) without) ×100(%) where σ_φ and σ_w are the square root of the variance of rolling amplitude and wave amplitude respectively, and with and without mean anti-rolling tank active and inactive respectively. Results showed that the tank was not effective in head seas, slightly effective in beam seas and considerably effective in following oblique seas. The maximum effectiveness of the tank reached about 50% which seemed to be a satisfactory result.
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Tatsuo KASHIWADANI, Shuichi KITAGUCHI, Hidekazu YASUOKA
Article type: Article
Pages
29-38
Published: December 30, 1977
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It is an important problem to estimate the course stability of full-bodied, e.g., large tankers. Although model experiments are usefull for this purpose, a difficulty comes from the fact that some models have unusually good stability on course which may or may not correspond to the full-size behavior. At the same time rather a fickle behavior on course is often experienced. In this paper such unusually stable phenomenon and its possible cause are discussed and the concerning hydrodynamic forces were measured for the two typical models of 4.5 meter long ; one is unstable model and another unusually stable one, both having the same principal dimensions. The hydrodynamic derivatives obtained from the measured forces are compatible with the course stability observed at the free sailing model tests. Differences between the hydrodynamic derivatives of the two models are seen for Y_β', N_β', Y_r', N_r' and the cause is supposed by the differences on the aft-framelines and stern profile. The difference is not seen on the rudder force, but seen on the aft-body force. The propeller revolution affects remarkably to the hydrodynamic forces on the aft-body and seems to play an important role on the above mentioned unusual stability on course.
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Matao TAKAGI, Takamune KITAZAWA
Article type: Article
Pages
39-45
Published: December 30, 1977
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Two problems relating to the efficiency of a propeller behind a ship are discussed by the simple momentum theory. The conclusions thus obtained are as follows : 1. Maximum ideal efficiency of a propeller behind a ship can be over 1.0 and is given by η_<max>=1/(1-(W_f)/2). where η_<max> : maximum efficiency W_f=1-V_a/V : frictional wake coefficient V : velocity of the uniform stream V_a : propeller advance speed In the ideal condition, thrust deduction factor (t) is related to the wake coefficients by t=(W_p)/(1-(W_f)/2). where W_p : potential wake coefficient 2. Non-uniformity effect of the ship's wake upon the propeller efficiency can be estimated by modified relative rotative efficiency (η'_R), which is defined by making use of the nominal wake coefficient (W_n). η'_R = (NQ)/(N_0Q_0) where N, Q : propeller r.p.m. and torque in the non-uniform stream, whose mean velocity equals to V(1-W_n). N_0, Q_0 : propeller r.p.m. and torque in the uniform stream whose velocity equals to V(1-W_n), to produce the same thrust as the one in the case of N and Q.
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Junkichi YAGI, Toshiyasu TSUNENARI, Hideo ONO
Article type: Article
Pages
47-54
Published: December 30, 1977
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To estimate the crack propagation under random loading more accurately, crack propagation model which takes into consideration the retardation effect in crack propagation is proposed and experiments for verification of this model were carried out. This model is composed of the assumptions as follows : (1) The area in which retardation effect occurs is decided by plastic zone at crack tip. (2) The crack propagation rate (dl)/(dN) at the retardation area is given by (dl)/(dN) = C'・Δ K^m' C' = C・ΔK^<m-m'>_<lm> where C and m are material constants, Δ K is range of K value, m' is material constant at the retardation area and ΔK_<lm> is ΔK value which decides the crack propagation hehavior at the retardation area. Numerical simulation tests using this model showed good agreement with results of crack propagation tests for SM58Q specimen under quasi-random loading tests.
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Hiroo OKADA, Yoshio FUKUMOTO
Article type: Article
Pages
55-64
Published: December 30, 1977
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As a basic study on the buckling strength of a ship's bottom plating, deformation behaviour and buckling strength of rectangular plate (aspect ratio α=2) with four clamped edges, and infinitely long plate (α=∞) with opposite edges simply supported or clamped, subjected to compression and hydrostatic pressure, are theoretically clarified in this paper. And the effect of edge conditions on the buckling strength of plates under such combined loads, is also discussed.
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Yoshikazu MATSUURA, Kenji ARIMA
Article type: Article
Pages
65-73
Published: December 30, 1977
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This paper deals with an investigation into the causes of the difference between theoretical J values for ellipsoid of revolution calculated by Lewis, Taylor, Macagno and the present authors and experimental ones obtained by Townsin and the present authors. J values are accurately calculated using actual mode shapes obtained by experiments, resulting in slightly different values from experimental ones. On the other hand, natural frequencies calculated by Ritz method considering virtual mass distribution in the form of 'local j values' are in good agreement with those obtained by model tests. In addition, it is tried to study the effect of acceleration due to advance movement on the added virtual mass of ellipsoid of revolution vibrating in water.
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[in Japanese]
Article type: Article
Pages
75-84
Published: December 30, 1977
Released on J-STAGE: March 30, 2018
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[in Japanese]
Article type: Article
Pages
85-92
Published: December 30, 1977
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[in Japanese]
Article type: Article
Pages
93-98
Published: December 30, 1977
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Article type: Appendix
Pages
99-101
Published: December 30, 1977
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Article type: Appendix
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App2-
Published: December 30, 1977
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Article type: Appendix
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Published: December 30, 1977
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Article type: Appendix
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Published: December 30, 1977
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Article type: Cover
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Published: December 30, 1977
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Article type: Cover
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Published: December 30, 1977
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