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Article type: Cover
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Published: December 30, 1980
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Article type: Cover
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Published: December 30, 1980
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Article type: Appendix
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Published: December 30, 1980
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Article type: Appendix
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Published: December 30, 1980
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Article type: Appendix
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Published: December 30, 1980
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Susumu HASEGAWA, Shigeru NAITO, Hideyasu YAOI
Article type: Article
Pages
1-6
Published: December 30, 1980
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In the previous paper, the authors studied on the room air environment of the ferry and passenger boats operated near Japan Sea. In the present paper, the same measurements were carried out for a container ship operated between Japan and U.S. Pacific coast. It is found that the air environment for the container ship is almost within the range of the Air Quality Standards for Building Maintenance and the respirable aerosol density and CO contents are influenced by smoking. Those results correspond to the ones of the previous paper. However, the room humidity of the container ship is shown to be in a better condition than the one of the ferry and passenger boats.
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Nobuya TSUSHIMA
Article type: Article
Pages
7-12
Published: December 30, 1980
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Recently, there are some Classification Societies which approve exposed hatch covers of non-weathertight construction with no packing. However, it is necessary to prove no possibility that cargo holds might be flooded by deck wetness when such a vessel as is provided with non-weathertight hatch covers is navigating under the bad sea condition. The method of predicting the short term probability of deck wetness is applied to calculating how much amount of water leakage can arise from omitting packings. As the result of the study, we obtained a practical way of predicting water leakage into cargo holds through the clearance between hatch covers and coamings. Actual calculations show that water leakage, for example on the container ship with a comparatively high freeboard, is so little that non-weathertight hatch covers can be adopted. We believe that these results can bring less initial cost and also less maintenance not only to shipyards but also to ship operators.
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Yoshiaki SEZAKI
Article type: Article
Pages
13-17
Published: December 30, 1980
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Effects of the wind force to the maneuverability of the ship with a large lateral area above the water line have been reported in many papers, however, few have refered to the speed loss during the navigation with helm adjusts and drifts due to the oblique wind. This paper shows the results of an estimation of the speed loss for a large car carrier by incorporating equilibrium equations and the results of various model tests, such as the wind tunnel test, resistance test with drifts and self-propulsion test with helm adjusts. From this study, it can be considered that the speed loss due to drifts and helm adjusts can't be ignored compared with that due to the wind resistance.
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Shoichi NAKAMURA, Shigeru NAITO, Shoichi HARA, Koichiro MATSUMOTO
Article type: Article
Pages
19-26
Published: December 30, 1980
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We have been trying to synthesize the seakeeping qualities for obtaining the speed loss of ships in waves. However, the deliberate speed loss is not so investigated in detail as the nominal speed loss. In this paper, the detail of the prediction method taking the characteristics of the main engine into consideration is presented. It is fact that the method of the experiment about the deliberate speed loss is not established. Therefore, an experiment about the deliberate speed loss are carried out with a model of single screw high speed container ship in order to ensure the justification of the predicted calculation.
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Minoru SAKAO, Noritsugu SHIMOYAMA
Article type: Article
Pages
27-34
Published: December 30, 1980
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In this paper, authors propose a simple method to calculate pressure distributions on the hulls and stern waves of transom-stern ships by slender ship theory. Numerical calculations of a few transom-stern ships by this method resulted in good agreement in tendency with our experiences.
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Norio TANAKA, Yoshiho IKEDA, Yoji HIMENO, Yasushi FUKUTOMI
Article type: Article
Pages
35-43
Published: December 30, 1980
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The viscous forces acting on various oscillating bluff cylinders are measured by using a forced oscillation mechanism in order to clarify the influences of Reynolds number, KC number, the cross sectional aspect-ratio and the round edge on the drag and the added-mass coefficients. From the experimental results, it is found that the characteristics of the drag coefficients of rectangular cylinders with small sectional aspect-ratio at low KC number (KC<4) vary significantly with a slight change of the sectional aspect-ratio. The flow visualization results indicate that the change of the drag coefficients is highly related to the existence of the reattachment of the front-edge separation flow at the body side. The effect of the round edge on the drag is greater for the shape like a square than for the cylinder with small sectional aspect-ratio like a flat plate. In the region of KC number under 6, the added-mass coefficients of rectangular cylinders increase with KC number due to the created vorticies, while their values at KC number above 6 become different depending on their sectional aspect-ratios. For round-edge cylinders the added-mass coefficients are almost constant at KC number under 6, and have the same tendency as the rectangular cylinders at KC number above 6.
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Norimasa KAWAMURA, Hisashi KAJITANI, Hideaki MIYATA, Yoshiro TSUCHIYA
Article type: Article
Pages
45-55
Published: December 30, 1980
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The resistance component due to free surface shock waves is experimentally examined with a great number of series ship models. Resistance tests, wave analyses, momentum loss measurements and observation of wave patterns by photograph are undertaken for beam-length series ships, draft series ships, entrance angle series ships and bulbous bow series ships. The effects of these hull parameters on the resistance component due to free surface shock waves are clarified and visualized in various forms. Based on the analysed experimental results some guidelines for hull form design are presented. The resistance component due to free surface shock waves is approximately discriminated and its dependence on hull particulars is discussed, together with the implication of shock angle.
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Yeun Junn LIN, Hisashi KAJITANI, Hideaki MIYATA, Makoto KANAI
Article type: Article
Pages
57-65
Published: December 30, 1980
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A new procedure for the improvement of the aft-part of fine hull forms is developed, which is based on the method of calculating inviscid resistance for propelling ships. Wave resistance and resistance caused by the presence of a propeller are simultaneously calculated for systematically modified hull forms. The new hull form thus obtained is empirically modified by attaching a stern bulb so that its wake comes to be desirable. The resistance and propulsion efficiencies of the original and the optimized hull forms are examined through some kinds of experiments, which show that the total efficiency of the optimized hull form is raised by about 10 percent. Resistance increment due to the action of a propeller is also discussed with experimental results. Waves and the uniformity of wake play significant roles in the interaction of a hull with a propeller.
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Hiroshi ISSHIKI
Article type: Article
Pages
67-73
Published: December 30, 1980
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Water waves due to a rotating unsteady singularity are discussed. These may be important in relation to the theoretical treatments of water waves generated by a rotating force due to a typhoon, and of motions of a ship turning in waves. A general expression is given for water waves due to a rotating unsteady singularity. By using the result, a numerical example is given for the wave making resistance induced by the displacement effect of a ship turning in still water, and an interesting numerical result is obtained in the region of the high Froude number.
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Masao TOYODA, Kunihiko SATOH
Article type: Article
Pages
75-82
Published: December 30, 1980
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Effects of fracture toughness distributions in the vicinity of pre-existing notches on fracture performance have been studied with reference to fracture toughness evaluation of welds. Fracture toughness tests and fracture performance tests are carried out using the specimens made from HT 80 steel welded joints and stainless explosive clad steels. In the present paper, effect of local embrittlement on toughness evaluation is paid major attention. In the case which notch tip exists in the local embrittlement zone, fracture initiation is dominated mainly by fracture toughness of local embrittlement zone. When the embrittlement is much remarkable, it may be reasonable that short crack arrest toughness of base metal is adopted as fracture toughness for evaluating joint performance because multi-stage fracture occurs inevitably. In the case which local embrittlement zone exists at a short distance from notch tip, fracture behaviors are dependent on the plastic deformation in the vicinity of notch tip under loading. Fracture toughness of local embrittlement zone has become dominated fracture behaviors when plastic zone front occured in the vicinity of notch tip reaches the embrittlement zone.
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[in Japanese]
Article type: Article
Pages
83-92
Published: December 30, 1980
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[in Japanese], [in Japanese]
Article type: Article
Pages
93-99
Published: December 30, 1980
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[in Japanese]
Article type: Article
Pages
101-106
Published: December 30, 1980
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Article type: Appendix
Pages
107-108
Published: December 30, 1980
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Article type: Appendix
Pages
109-
Published: December 30, 1980
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Article type: Cover
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Published: December 30, 1980
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Article type: Cover
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Published: December 30, 1980
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