الفهرس | Only 14 pages are availabe for public view |
Abstract The aim of the thesis is to assess the advantages as well as the possibility for the adoption of the surface effect technology in the design and for conversion of conventional high speed boats. All characteristics and forces, which act on the planing hull type and air cushion vehicle (ACV) type, were studied. Also, the lifting force, thrust and lifting power to generate air cushion under the ACV type were calculated. A conventional surface effect ship (SES) rides on air cushion, which is contained, between the twin hulls of a catamaran. To contain the air cushion, flexible skirts are necessary at bow and stem and these can provide a major maintenance problem. The flexible skirts are replaced after 500 - 1000 hr or six months of commercial service and there are excessive losses in the lift power due to the more air leakage between the bow and f~rward skirts. Recently a new concept based on SES, which requires no skirts, was developed. The concept utilizes a catamaran hull with the air cushions contained under the two side hulls rather than between them. The new concept through model tests showed that the resistance when riding on the air cushions was between 50 percent and 60 percent of that of conventional monohull and catamaran designs. A case study of an existing naval unit was carried out to implement the unskirted SES concept in such a way to reduce the required power at a given speed or to gain higher speed at the same power. Three different constructional proposals are suggested. The resistance, propulsive and lifting power are calculated and compared with the conventional boat performance. The conversion process resulted in a 45 to 50 % reduction in power and about 60 % reduction in resistance. |