International Shipbuilding Progress - Volume 5, issue 52

Authors: Gerritsma, J.

Article Type: Research Article

Abstract: In the current literature on seaworthiness, it is generally assumed that the pitching and heaving motions of a ship in longitudinal regular waves can be described with sufficient accuracy by a set of two coupled linear differential equations of the second order with constant coefficients. Using a model, performing forced oscillations in still water, the coefficients of these differential equations are determined experimentally for an 8 ft. model of the Sixty series with a blockcoefficient of .60. The exciting forces and moments are measured on the restrained model in waves. Four modelspeeds and a wide frequency range are …considered. The solutions of the differential equations, determined in this manner, are compared with the measured motions of the same model in regular waves. A good agreement is found between the computed and measured modelmotions. It is shown that some of the so called coupling terms, have an important influence on amplitude and phase of the model motions. Show more

DOI: 10.3233/ISP-1958-55201

Citation: International Shipbuilding Progress, vol. 5, no. 52, pp. 533-542, 1958

Authors: Murray, J.M.

Article Type: Research Article

Abstract: This paper describes the practice adopted by Lloyd’s Register for determining the section modulus of large tankers. Account is taken of both the still-water bending moment and the wave bending moment and the paper indicates the bases adopted for determining these two components, and the stresses which are associated with them. Some remarks on the effect of design features on the still-water bending moments, on the disposition of the material in the midship section, and on the local strength of the main hull girder are made.

DOI: 10.3233/ISP-1958-55202

Citation: International Shipbuilding Progress, vol. 5, no. 52, pp. 543-553, 1958

Authors: Cartwright, D.E.

Article Type: Research Article

Abstract: The vertical components of velocity and acceleration of any part of a rigid ship heading into sea waves are discussed in statistical terms appropriate to random motions, and related to the wave motions. To illustrate the theory, results of some measurements made on R.R.S. Discovery II , using a shipborne wave recorder and two accelerometers, are analysed harmonically and statistically.

DOI: 10.3233/ISP-1958-55203

Citation: International Shipbuilding Progress, vol. 5, no. 52, pp. 554-565, 1958

Authors: Schultze, W.A.

Article Type: Research Article

Abstract: If in a marine diesel engine chromium plated liners are used and if this engine runs on a fuel with a high sulphur content, a difference in potential between the cylinder-wall and the piston can be measured. This potential difference is due to the existence of a galvanic cell formed by the chromium plated wall and the cast iron piston-rings with an acid oil film on the wall as electrolyte. From the results on a test engine could be calculated that an important part of the corrosive wear of the chromium plated liners is due to the action of this …cell. Methods for the prevention of this kind of corrosive wear will be mentioned further on. Show more

DOI: 10.3233/ISP-1958-55204

Citation: International Shipbuilding Progress, vol. 5, no. 52, pp. 566-576, 1958

Authors: Völker, H.

Article Type: Research Article

DOI: 10.3233/ISP-1958-55205

Citation: International Shipbuilding Progress, vol. 5, no. 52, pp. 577-580, 1958