ESTIMATION OF POWER OF SHIPS

When constructing diagrams for predicting the power requirement of proposed new ships, the choice of parameters is of the greatest importance. There are many to choose from, and if simple diagrams are wanted, a selection must be made. The Author, of the Technical University of Denmark, discusses the selection of these parameters, and suggests that, if it is assumed that the diagrams should involve only four parameters, these could be displacement, ship speed, block coefficient, and length/displacement ratio. All the other parameters would then have to be "standardised"; he describes how this can be done. A method of deriving power-prediction diagrams on the basis of this selection of parameters, including the determination of shaft power from effective power, is explained, and a series of such diagrams, one for each of seven block coefficients varying from 0.55 to 0.85, is presented. In each of these graphs, the abscissa is displacement in tonnes, the ordinate is shaft power in kW, and curves of constant speed are plotted for three length/displacement ratios. The diagrams will give a prediction of the propulsion power required for a given speed of the standard ship in the standard condition. Service allowance will need to be added in accordance with the owner's wishes. If the designer has his own standard form for the hull, he can make use of the same parameters as in these diagrams and construct power curves for his standard form; such diagrams give a very reliable power prediction.

  • Availability:
  • Corporate Authors:

    International Periodical Press

    193 Heemraadssingel
    Rotterdam,   Netherlands 
  • Authors:
    • Harvald, S A
  • Publication Date: 1978-3

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Filing Info

  • Accession Number: 00180043
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Files: TRIS
  • Created Date: Sep 14 1978 12:00AM