International Shipbuilding Progress - Volume 4, issue 38

Authors: Gerritsma, J.

Article Type: Research Article

Abstract: The damping, added mass and mass moment of inertia of a shipmodel, performing forced heaving or pitching oscillations in calm water, are determined experimentally. The influence of model speed, amplitude and frequency of the motions on these quantities has been studied. The coupling terms in the case of a combined heaving and pitching motion are considered for one model speed. Some of the experimental results are compared with calculated values, which have been published recently.

DOI: 10.3233/ISP-1957-43801

Citation: International Shipbuilding Progress, vol. 4, no. 38, pp. 505-519, 1957

Authors: Korvin-Kroukovsky, B.V. | Jacobs, Winnifred R.

Article Type: Research Article

Abstract: The effect of the circumferential non-uniformity of the thrust distribution on the propeller inflow is quantitatively investigated in the present paper: expressions are derived for the velocity potential and for various components of the inflow velocities resulting from this non-uniformity. The calculation of the propeller inflow velocity for the case of a circumferentially uniform thrust distribution was presented in a previous paper. The objective of that work was to provide material for the calculation of the wake fraction and thrust deduction of a ship propeller. Jr was pointed out at the same time that the thrust deduction probably would …be strongly affected by the circumferential non-uniformity of the thrust distribution and so the present task of calculating the velocities induced by this non-uniformity was initiated. The study was conducted at the Experimental Towing Tank, Stevens Institute of Technology, under Office of Naval Research Contract No. N6onr-24705, sponsored by the Bureau of Ships under Project No. NS715-102, and technically administered by the Director, David Taylor Model Basin. Show more

DOI: 10.3233/ISP-1957-43802

Citation: International Shipbuilding Progress, vol. 4, no. 38, pp. 520-530, 1957

Authors: Jung, Ingvar | Ohlsson, Gunnar

Article Type: Research Article

DOI: 10.3233/ISP-1957-43803

Citation: International Shipbuilding Progress, vol. 4, no. 38, pp. 531-541, 1957

Authors: Radosavljević, Lj.B.

Article Type: Research Article

Abstract: The influence of the inclination of a ship’s sides to the vertical in the vicinity of the flotation surface on the motion of the ship in a seaway was discussed by A.N. Kriloff [1], I.G. Boobnov [2] and F. Horn [3]. Their discussions were limited to the calculation of this effect for particular ships only of given dimensions and forms. The author deduces the differential equations of motion for additional oscillations caused by the above mentioned factor in the way shown by I.G. Boobnov [2] and substitutes the real frame lines at the ship’s ends by approximate analytical curves …corresponding to the main characteristics and dimensions of the ship. The inclination of these lines varies considerably. The author shows (for the case when the length of the waves λ is equal to that of the ship L ): a. that in ships of usual form the influence of the deviation of the sides from the vertical is considerably smaller than that of the Smith Effect, and compared to it can be neglected, and b. that the ratio T / L has a contrary influence on the Smith Effect as compared with the correction due to the deviation of the sides from the vertical. Show more

DOI: 10.3233/ISP-1957-43804

Citation: International Shipbuilding Progress, vol. 4, no. 38, pp. 542-550, 1957

Authors: Vossers, G.

Article Type: Research Article

Abstract: This paper gives a review of the communications, which were discussed from 7–10 September 1957 at the First International Symposium on the Behaviour of Ships in a Seaway, Netherlands Ship Model Basin, Wageningen.

DOI: 10.3233/ISP-1957-43805

Citation: International Shipbuilding Progress, vol. 4, no. 38, pp. 551-558, 1957