In this paper an approximate method is introduced to calculate the swaying force, yawing and rolling moments acting upon a ship navigating in oblique waves. It next treats the linear coupled equations of swaying, yawing and rolling motions, where the ship has a finite velocity, in order to derive an approximate method for solving the problems of forced oscillation. As the first step for studying such coupled motions in three degrees of freedom in a lateral plane, the author investigated mutual coupling actions among swaying, yawing and rolling motions when ship velocity is zero. That is to say, the author worked out a numerical calculation for three kinds of hull forms by means of the linear coupled equations of swaying, yawing and rolling motions which he derived in 1965 for the case of zero ship velocity. The results can be summarized as follows: a) In case of a hull form with cut up stern, there is a remarkable coupling action between yawing and rolling motions. Also in this case, if yawing motion is restrained, rolling amplitude will find its maximum value in quartering seas. b) Depending on hull shapes, it may be possible that we may find rolling amplitude at its maximum in quartering seas because of the coupling actions of swaying and yawing. c) When a ship has a cross section of large beam/draft ratio, the coefficient of effective wave slope sometimes becomes much larger than that of Watanabe's theoretical calculations.

  • Corporate Authors:

    Society of Naval Architects of Japan

    23 Shiba-kotohiracho, Minato-ku
    Tokyo 135,   Japan 
  • Authors:
    • Tasai, F
  • Publication Date: 1969

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00035083
  • Record Type: Publication
  • Source Agency: Society of Naval Architects of Japan
  • Files: TRIS
  • Created Date: Oct 27 1972 12:00AM