At present, the major economic factor in the operation of tankers with steam turbine propulsion is the rapidly increasing price of fuel oil. In Spain, this has increased from 1,100/1,300 to 4,700/5,000 pesetas per ton in a relatively short time. For a typical tanker haul between Spanish ports and the Persian Gulf, fuel costs alone are estimated at between 30 to 35 million pesetas, representing some 21 to 27.5% of the total costs of the voyage. In order to improve fuel consumption it has become necessary to operate these ships at reduced power which means that the propulsion machinery is used outside its designed operating conditions. This paper discusses a study of the various factors, both technical and economic, affecting the operating of tankers at reduced power. Following the derivation of some formulae for calculating fuel consumption under various conditions. Part II of the paper presents an analysis of the technical factors affecting the operation of the machinery at reduced power. Consideration is given to ships in the power range 20,000 to 40,000 shp for which some thermal balances are calculated. Part III discusses briefly the use of power/speed/rpm curves, and Part IV details the maximum benefits to be obtained from observation of these simple sailing rules and also presents quantitative data from a study of four ships to show the effects of deadweight, state of the hull, length of voyage and fleet tariffs. It is concluded that it is economically advantageous to operate ships at slightly reduced power provided certain modifications are made; these include periodic recording of speed, re-structuring of charter rates and the development of re-heat turbines. Order from BSRA as No. 49,318.

  • Corporate Authors:

    Asociacion de Ingenieros Navales

    Apdo Correos 457
    Madrid,   Spain 
  • Authors:
    • Parga, FJS
    • Carro, J D
  • Publication Date: 1977-7


  • Spanish

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00185307
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Files: TRIS
  • Created Date: Jan 13 1979 12:00AM