In the initial design of ships, a convenient method to estimate the maximum velocity of wind in which a ship is manoeuverable and a method to adjust the results of the turning trials are required. In order to establish them, the authors investigated the motions of a ship in wind by solving the nonlinear equations of motion of a ship, which involved the experimental wind resistance data by using a digital computer. In this report, the author investigated the course stability and the method to estimate the freely manoeuverable range of the wind velocity, and came to the following conclusions. (1) A ship whose course keeping quality is unstable is made stable in the range of the wind velocity wind direction between specified maximums. (2) In the aft and quarter wind a ship becomes unstable, and in the head and bow wind the ship whose lateral projected area above the water line is large becomes unstable. (3) The unstable equilibrium condition becomes stable by the steering in proportion to the heading angle theta and the degree of the instability can be showed by the minimum of the proportional constant. (4) The centroid of the lateral projection above the water line is drawing toward the bow, the limited manoeuverable range grows wide, however, the instability grows great in the bow and head wind, but decreases in the quarter and aft wind.

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    Society of Naval Architects of Japan

    15-16, Toranomon, 1-chome, Minato-ku
    Tokyo,   Japan 

    Society of Naval Architects of Japan

    15-16, Toranomon, 1-chome, Minato-ku
    Tokyo,   Japan 
  • Authors:
    • Ishibashi, Y
  • Publication Date: 1975

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  • Accession Number: 00323619
  • Record Type: Publication
  • Source Agency: Stevens Institute of Technology
  • Files: TRIS
  • Created Date: Nov 19 1980 12:00AM