Response behaviour of a ship to steering is described with the transfer function in steering. A simplified analysis is based upon this idea and has a wide utility to measure and to assess manoeuvrability of ships. This simplification is, however, not valid for the analysis and synthesis of steering control of a ship, in which we should take an automatic steering device and/or a human operator into account. Here the complete transfer function should be called upon to describe the ship behaviour. This paper relates to a new procedure of defining the transfer function using a radio-controlled, freesailing model. This principle can also be adopted to a full-size experiment. The procedure employs two manouvres; parallel shifting of the ship's track and periodic steering with a number of frequencies. Both manoeuvres can be performed in a conventional towing basin. The harmonic analysis of the parallel shift manoeuvre gives, together with the amplitude and phase of yawing motion measured on the periodic steering, information enough to assess the transfer function of a ship, which facilitates to determine the characteristic constants. These constants are composed of eight stability derivatives (coefficients of the linear equation of motion), so that we can define these derivatives through the present approach if four of these derivatives are given by any other sources, for example, oblique towing test. The data involved were obtained at the Osaka University Experiment Tank No. 2, using two 4.5 metre models out of Todd 60 series.

  • Corporate Authors:

    Society of Naval Architects of Japan

    23 Shiba-kotohiracho, Minato-ku
    Tokyo 135,   Japan 
  • Authors:
    • Nomoto, K
    • Karasuno, K
  • Publication Date: 1971

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Filing Info

  • Accession Number: 00035107
  • Record Type: Publication
  • Source Agency: Society of Naval Architects of Japan
  • Files: TRIS
  • Created Date: Oct 27 1973 12:00AM