SINGLE- AND TWIN-SCREW PROPULSION OF TANKERS AND BULK CARRIERS
In this paper a comparative analysis is carried out regarding required shaft horse power for large tankers and bulk carriers. In the first instance single- and twin-screw propulsion are compared generally, but efforts are also made to judge some alternatives of twin-screw propulsion. The study is limited to large and full ships, VLCCS and ULCCS, i.e. ship lengths above 300 meters (deadweights above about 200,000 tons). The hull block coefficient is mostly higher than 0.80. The analysis is based on about 400 self propulsion test series carried out for such ships at the Swedish State Shipbuilding Experimental Tank (SSPA). This material is supposed to be the most extensive on one hand outside Japan. All data for the present analysis are derived from the SSPA hull form data bank, which now comprises nearly 5,000 hull forms for merchant ships. During the investigation special interest has been devoted to the twin-skeg (or twin-gondola) form, as this afterbody has lately been very much discussed as a realistic alternative to the conventional twin-screw hull form. While the difference in total required shaft horse power is rather small between single-screw and conventional twin- screw propulsion, there are clear indications that gains in SHP of 5 percent and more can be achieved by use of the twin-screw twin-skey principle.
- Presented at the First Ship Technology and Research (STAR) Symposium, Washington, D.C., August 26-29, 1975.
Society of Naval Architects and Marine Engineers601 Pavonia Avenue
Jersey City, NJ USA 07306-2907
- Williams, A
- Publication Date: 1975-8
- Features: References;
- Pagination: 13 p.
- TRT Terms: Boundary layer separation; Engine efficiency; Propulsion; Wakes
- Old TRIS Terms: Propulsive efficiency; Twin screws; Wake analysis
- Subject Areas: Marine Transportation; Vehicles and Equipment;
- Accession Number: 00126940
- Record Type: Publication
- Source Agency: Society of Naval Architects and Marine Engineers
- Report/Paper Numbers: #12
- Files: TRIS
- Created Date: Nov 5 1975 12:00AM