International Shipbuilding Progress - Volume 5, issue 51

Authors: Cutland, R.S.

Article Type: Research Article

Abstract: In this paper, experiments to determine the relation between velocity in the boundary layer, the distance from the surface of the body, and the shearing stress at this surface are described. Various lengths of pontoon were used at two speeds, and the deduced law u u ∗ = 4.98 log u ∗ y v + 6.54 agrees very closely with that found by Ludwieg and Tillmann, but differs considerably from the more commonly used Nikuradse value. Velocities in the boundary layer of …two ships were also measured. The first was a trawler, two traverses being made at approximately the same distance from the bow, about 0.6 of the length of the ship. The traverse in the position on the flat bottom gave a typical velocity distribution curve, but that carried out in the side position showed marked fluctuations in the value of u U with increasing y . The second ship was an ore carrier, traverses being made in six positions around a girth about 0.3 of the ship’s length from the bow. Considerable variations were observed, both of the boundary-layer width and the free-stream velocity at the edge of the boundary layer. An attempt was made by using the pontoon results, and also by using Ludwieg and Tillmann’s formula, to find C f ′ at each of the positions, but the disagreement between the two methods throws some doubt on the validity of their use in 3-dimensional flow. Show more

DOI: 10.3233/ISP-1958-55101

Citation: International Shipbuilding Progress, vol. 5, no. 51, pp. 493-499, 1958

Authors: Towle, E.L.N.

Article Type: Research Article

Abstract: A review of various forms of electric ship propulsion, comparing the a.c. and d.c. transmission systems at present in use, and indicating the types of vessel in which each is most effective.

DOI: 10.3233/ISP-1958-55102

Citation: International Shipbuilding Progress, vol. 5, no. 51, pp. 500-514, 1958

Authors: Cockcroft, John

Article Type: Research Article

Abstract: The lecture reviews the present state of development of nuclear propulsion for shipping in the light of the technical performance of the U.S. nuclear submarines and the information disclosed at the Geneva Conference on the development of commercial nuclear propulsion. Five types of nuclear reactor for propulsion purposes have so far been considered: the pressurized-water reactor, the boiling-water reactor, the sodium-cooled reactor, the gas-cooled graphite-moderated reactor and the organic-liquid-moderated reactor. The pressurized-water reactor has been adopted for nearly all U.S. Naval units and by the U.S.S.R. for their icebreaker, but capital costs are high. On present information the …boiling-water reactor seems likely to have appreciably lower capital costs than the pressurized-water reactor, and with substantial development it seems not impossible that capital costs of this system might approach those of the conventional propulsion systems. Fuel costs for nuclear propulsion systems depend on the cost of enriched fuel and on the cost of fabrication of fuel elements, which are at present very high. To achieve fuel costs equal to oil-fuel costs would require the use of low cost enrichment. Under these conditions and if capital charges can be brought into approximate parity, nuclear propulsion would have a chance of being competitive. This time seems, however, to be some distance away. Nevertheless it may be desirable to gain practical experience in this field so that the future role of nuclear propulsion can properly be judged. Show more

DOI: 10.3233/ISP-1958-55103

Citation: International Shipbuilding Progress, vol. 5, no. 51, pp. 515-521, 1958

Authors: Johnson, N. Vilhelm

Article Type: Research Article

DOI: 10.3233/ISP-1958-55104

Citation: International Shipbuilding Progress, vol. 5, no. 51, pp. 522-529, 1958