THE OPTIMUM SPEEDS OF A SHIP

After pointing out that operating a ship at a reduced speed does not necessarily lower the fuel costs as much as might be expected, the Author, of the Societe Ivoirienne de Transport Maritime (SITRAM), presents simple methods for the calculation of "economic" ship-speed and "profitable" ship-speed. The methods are illustrated with numerical examples, together with associated curves showing (i) operating cost per day at sea, against speed; (ii) cost per nautical mile, against speed; (iii) profit per day, against speed; and (iv) profitable speed, taking into consideration the voyage distance and the time spent in port. The methods of calculation are extended to determine maximum profitability, and it is shown that, at the ship's profitable speed, the total cost of fuel for propulsion during a voyage varies between one-third of the net freight charged (if the time spent in port is negligible) and one-fifth of this freight (if the time spent in port is equal to that spent at sea) as a first approximation. The theoretical profitable speed here considered depends on the net freight per mile, the voyage distance, the time spent in port, and the cost of the fuel, but other factors may, in practice, affect the speed at which the ship is operated. The study concerns only ships in service, but its methods could be applied to new projects; although precautions would then be necessary because the profitability criteria for new ships are more sophisticated than those here considered, the present methods may be usefully employed to give rough estimates of speeds applicable to various hypotheses.

  • Corporate Authors:

    Bureau Veritas

    One Western Union International Plaza
    New York, NY  USA  10004
  • Authors:
    • Jamin, P
  • Publication Date: 1977-4

Language

  • French

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00159936
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Files: TRIS
  • Created Date: Sep 20 1977 12:00AM