An analytical method for the determination of conventional merchant ship motions and wave-induced moments in a seaway is developed. Both vertical and lateral plane motions and loads are considered for a ship travelling at any heading in regular waves and in irregular long or short crested seas. Strip theory is used and each ship hull cross-section is assumed to be of Lewis form shape for the purpose of calculating hydrodynamic added mass and damping forces in vertical, lateral and rolling oscillation modes. The coupled equations of motion are linear, and the superposition principle is used for statistical response calculations in irregular seas. All three primary ship hull loadings are determined, i.e. vertical bending, lateral bending and torsional moments, as well as shear forces, at any point along the length, with these responses only representing the low frequency slowly varying wave loads directly induced by the waves. A computer program that carries out the calculations was developed, and is fully documented separately. The results of the method are evaluated by comparison with a large body of model test data. The comparison extends over a wide range of ship speeds, wave angles, wave lengths, and loading conditions, as well as hull forms. The agreement between the calculations and experimental data is generally very good. Thus, a method is available for use in the rational design of the ship hull main girder structure.

  • Corporate Authors:

    Ship Structure Committee

    National Academy of Science, 2101 Constitution Avenue, NW
    Washington, DC  United States  20418
  • Authors:
    • Kaplan, P
    • Raff, A I
  • Publication Date: 1972-7

Media Info

  • Pagination: 50 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00040599
  • Record Type: Publication
  • Source Agency: Ship Structure Committee
  • Report/Paper Numbers: SSC-229
  • Contract Numbers: N00024-70-C-5076
  • Files: TRIS
  • Created Date: Jan 5 1973 12:00AM