The motion is investigated of a box-type floating vessel which is moored among regular waves in a sea of finite depth by chains and on which a constant drifting force acts. The present authors assume the floating vessel to be very blunt, and the length-breadth ratio of 1. The aim of the present report is to investigate the following problem: (1) Is the strip method acceptable for such a blunt body as the above mentioned from engineering standpoint? (2) How much is the nonlinear effect of the chain reaction on the motion of the floating vessel? The linearized equations of motion are solved analytically. On the other hand, the nonlinear equations of motion are integrated numerically by Runge-Kutta-Gill method. The results of the theoretical calculations show the following: (1) If the various damping forces of the rolling motion could be estimated in any way, the motion of the blunt body among the waves may be estimated by the strip method. (2) If the initial tensions of the chains are small, the nonlinear effect of the chain reaction on the stationary harmonic motion of the floating vessel is very small. A rough standard condition for small tension is that the chains touch horizontally the sea bottom at the anchoring points. (3) When the unstationary or constant drifting force acts on the moored floating vessel and it drifts from the initial equilibrium position greatly, the nonlinear effect of the chain reaction is very large. Hence, the motion in irregular waves, under a constant drifting force or under a large initial tension should be estimated considering the nonlinearity of the chain reaction.

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  • Corporate Authors:

    Society of Naval Architects of Japan

    23 Shiba-kotohiracho, Minato-ku
    Tokyo 135,   Japan 

    Society of Naval Architects of Japan

    15-16, Toranomon, 1-chome, Minato-ku
    Tokyo,   Japan 
  • Authors:
    • Tagaki, M
    • Arai, S
    • Togano, Y
  • Publication Date: 1974-6


  • Japanese

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  • Accession Number: 00071547
  • Record Type: Publication
  • Source Agency: Society of Naval Architects of Japan
  • Files: TRIS
  • Created Date: Nov 12 1974 12:00AM