International Shipbuilding Progress - Volume 31, issue 354

Authors: Millward, A.

Article Type: Research Article

Abstract: Existing linearised wave theory for the resistance of a ship in both deep and shallow water has been used to calculate the effect of shallow water on a fast ship moving at high sub-critical and also at super-critical speeds. In earlier work the real hull was represented by a simplified hull shape which was symmetrical fore and aft with parabolic water planes and rectangular cross-sections. The present work improves the representation of the hull by replacing the rectangular cross-section with a wedge shape for a planing hull and a parabolic cross-section for a round bilge displacement hull. A comparison …of the calculated results with the available data shows that the change in hull cross-section only made a noticeable difference in the region of the sub-critical resistance peak and tended to slightly lessen the agreement between the theory and the existing experimental data. Show more

DOI: 10.3233/ISP-1984-3135401

Citation: International Shipbuilding Progress, vol. 31, no. 354, pp. 28-33, 1984

Authors: Cassella, P.

Article Type: Research Article

Abstract: The paper deals with a method to evaluate, at first stage of design already, statical and dynamical stability of a single screw cargo ship for any loading condition. D.T.M.B.’s series 60 and B.S.R.A.’s cargo ship standard series parent hulls with a reference displacement volume of 10,000 m3 at design draught have been examined. Relative buoyancy characteristics have been calculated and results have been normalized by means of geometrical similarity because of the different beam to draught ratios presented by the two series. Obtained data have been analyzed by regression technique on the basis of block coefficient C …B , moulded depth to draught ratio D/T , hull transverse angle and ratio of buoyant volume to displacement volume at design draught. A polynomial representation of CB coordinates is given for each series examined as well as for the series all together. A worked example has been carried out for two real ships and results fit fine previously calculated cross curves. Show more

DOI: 10.3233/ISP-1984-3135402

Citation: International Shipbuilding Progress, vol. 31, no. 354, pp. 34-48, 1984

Authors: Nassef, I.

Article Type: Research Article

Abstract: 1. In this paper the solution of basic equation of ship vibration, determination of frequency, response of ship main dimensions, and hull material quality at heaving is presented. 2. Predominant functions determining vertical frequency, ‘longitudinal distribution of: ship’s mass, surrounding water mass and bending stiffness’, are studied and approximated in series harmonic functions. Minor factors, ‘effect of shear stiffness and gravitational effect of virtual surrounding water’, are considered. 3. Comparison between author model result and those obtained by other methods is presented.

DOI: 10.3233/ISP-1984-3135403

Citation: International Shipbuilding Progress, vol. 31, no. 354, pp. 49-52, 1984