It has been considered that the mission of the automatic steering system of ships is to maintain a ships' course. However, the author would like to point out that this definition is not proper, because, there should be resonable limitation to the rudder angle in relation to the speed loss, that is: if an excessive rudder angle was taken to maintain the ship course it will induce considerable power loss. The real purpose of applying the automatic steering to a ship in a seaway is to bring her from one side to the other as fast as possible within a limited cost. Therefore, the author prefers to define the purpose of an automatic steering to be "to minimize the increase of resistance in a wide sense under the disturbance of wind or waves in the ocean." Making the use of this definition, the author obtained a performance index of the automatic steering system of ships at sea. A full scale measurement of yawing motion is also carried out on a cargo ship, "M.S. Florida-Maru" in Pacific Ocean to obtain the spectrum of angular rate which is affected by disturbance caused by wind or waves. Applying these results, some suggestions are obtained to improve the automatic steering system of ships, for example, 1) The rudder angle ratio has to be chosen not too large. 2) The weather adjustment of conventional system is injurious and cannot keep the rudder angle small, because it necessarily requires rather deep rate control. 3) We should pay attention not to make the rudder too sensitive to each wave.

  • Corporate Authors:

    Society of Naval Architects of Japan

    23 Shiba-kotohiracho, Minato-ku
    Tokyo 135,   Japan 
  • Authors:
    • Koyama, T
  • Publication Date: 1970

Media Info

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Filing Info

  • Accession Number: 00035127
  • Record Type: Publication
  • Source Agency: Society of Naval Architects of Japan
  • Files: TRIS
  • Created Date: Oct 27 1972 12:00AM