Journal of the Kansai Society of Naval Architects, Japan

At the design of a comparatively small ship with long hatch openings, it is an important problem to estimate transverse deflection of the hatch openings due to transverse load and longitudinal shear force. In order to research the mechanism of elastic deformation of hatch openings, an experimental work was carried out on a cargo ship with raised deck and long hatch openings under various load conditons. And the results were analysed by the bending theory of continuous beam on an elastic foundation, and effects of various factors on the deformation of the hatch opening were discussed.

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In an endeavor to assist the scrutiny of design conditions for acceleration from statistical viewpoint, long term measurement of acceleration frequency was successively taken on M.S. "OREGON-MARU" and "MONTANA-MARU" of the Kawasaki Line between February 1960 and February 1961 in North Pacific Ocean. The acceleration frequency measuring equipment which was installed on these ships and brought about the success in the preparation of statistical distribution of acceleration was specially made for this measurement and was designed to meet the following requirements. 1. It is highly desirable that the measurement can be made automatically as much as possible, because the data for acceleration must be taken continuously for a long period. 2. As the measurement data will be voluminous, it is desirable that the equipment will analyze the result quickly and automatically. Laying special emphasis on the above two items, following equipments were made. a. Boundary displacement type magnetic recorder with its accessories which records the wave form continuously in proportion to acceleration on the magnetic tape. b. Reproducing and counting device which automatically counts the amplitude frequency of acceleration from continuous recording magnetic tape. The former was used on the ships and the latter on land.

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Motions of vessels may be roughly divided into vibration and oscillation, which cause numerous difficulties on crew and ship. To these motions, it is necessary to clarify the allowable limits which assure safe operation of ship, strength of ship and crew working ability. There exist engineering researches and physiological ones about these allowable limits, especially about the limit from the viewpoint of physiologically unpleasant feelings of human beings. However, these researches were conducted independently from one another. The present study undertakes to combine these researches and to establish a consistent theory. In the 1st. report susceptibility of human beings to the motion of vehicles is dealt with. In the 2nd. report, motion sickness shall be physically interpreted, and a description of allowable limits for vibration and oscillation of vessels shall be given.

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The elastic behaviour of the orthogonally stiffened plate under lateral loads is very important problem in ship structure, and has been analysed by many investigators. But there are few papers discussed on the design criterion what construction might give the minimum weight. In this paper, the simpler stiffened plates are dealt of which all ends are built in and subjected to the lateral uniformly distributed loads, and maximum bending stresses and maximum deflection in the grillages are estimated to various types of the stiffened plates, keeping the total weight of structure to be constant. And relations between maximum stresses and structures are discussed.

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