When a ships speed is almost the same as the group velocity of dominant wave in following or quartering seas, the ship will be attacked by the highest waves successively under a certain probability. This phenomena is particularly dangerous, because such repeated attack of high waves will induce various bad effects on ship safety such as stability loss on wave crests, unstable or synchronous rolling motions, shipping water on deck, etc. This dangerous encounter wave group phenomena can be explained by analysing the feature of encounter wave spectrum which is transformed from wave spectrum of the sea state concerned. A dominant part of wave energy of the sea concentrates in a narrow band encounter wave frequency so that the ship encounters to waves likely as regular waves having a single encounter period. By introducing the new concept of wave energy concentration ratio, the author has determined the degree of danger to encounter to successive high waves. The model test results of two container ships have shown that the capsize probability is proportional to the wave energy concentration ratio. By using these results, the author proposes a diagram to judge the dangerous condition in relation with ship speed, encounter angle and wave period.

  • Supplemental Notes:
    • STAB 94, 5th Intl Conf on Stability of Ships and Ocean Vehicles; 7-11 Nov 1994; Melbourne, Florida, USA. Sponsored by SNAME, USA and RINA, UK. Procs. Publ by Florida Inst Technology, USA. Vol 1, Session 1 [15 p, 4 ref, 13 fig]
  • Authors:
    • Takaishi, Y
  • Publication Date: 1994


  • English

Subject/Index Terms

Filing Info

  • Accession Number: 00710962
  • Record Type: Publication
  • Source Agency: British Maritime Technology
  • Files: TRIS
  • Created Date: Aug 14 1995 12:00AM