Extensive model tests have been performed with a type of 9,000 TDW Swedish cargo vessel, owned by the Brostrom Group of shipping companies. The tests include conventional smooth water tests with geometrically similar models at different draught and trim, cavitation tests in irregular flow conditions, self-propulsion tests in head and following regular sea and manoeuvring experiments. Ship speed trial and service results are given together with results from extensive full-scale turning and stopping tests. The correlation between the model tests in smooth water and the ship trial results is discussed and correlation factors are given. The tests with geometrically similar models indicate that with the I.T.T.C. skin friction formulation similar full-scale predictions are obtained independent of model scale. This is not the case if the Froude formulation is used. It is concluded that the model propeller cavitation pictures give some indication with regard to danger for ship propeller erosion. However, many difficulties still exist when interpreting cavitation tunnel test results. The influence of the time out of dry-dock on the power required to maintain constant speed is discussed. Diagrams are given to illustrate the influence of wind and waves on power, rpm and speed. Turning data are presented from tests with a radio-controlled model and compared with ship trials. The ship turns better than its model. Small differences in model and ship engine load characteristics may affect the interpretation of model results. Partly on the basis of these tests is put forth a semi-empirical method for the prediction of minimum turning circles. The simplified linear theory is applied to the analysis of ship turning transients and to a zig-zag manoeuvre. Adequate information on turning lag index can only be obtained from measurements under ideal conditions, using small helm and a suitable conrrection for the interactions in the engine-propeller-rudder-ship system. Stopping tests with the model are compared with ship trials and with approximate calculations according to a new and simple method. There is reasonable agreement between the different results.

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  • Corporate Authors:

    Royal Institution of Naval Architects, England

    10 Upper Belgrave Street
    London SW1X 8BQ,   England 
  • Authors:
    • Lindgren, H
    • Norrbin, N H
  • Publication Date: 1961

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  • Accession Number: 00323649
  • Record Type: Publication
  • Source Agency: Stevens Institute of Technology
  • Files: TRIS
  • Created Date: Mar 12 1981 12:00AM