Speed loss in waves and wave-induced torsion of a wide-breadth containership

Abstract

Aspects relevant for operational and structural design of a wide-breadth, neo-panmax containership were addressed. First, speed loss in waves was investigated. Second, wave-induced global hull girder torsion was determined to assess the effects of the increased breadth on this load component, generally considered critical for the ship’s structural strength. An extended Reynolds-averaged Navier–Stokes (RANS) equations solver simulated the ship advancing in calm water as well as in selected regular head and bow waves. A boundary element method (BEM) computed transfer functions of wave-induced ship response. Before using spectral techniques to obtain long-term predictions of hull girder torsion, these transfer functions were corrected to account for non-linear effects. To assess the reliability of the computed long-term hull girder torsion, the extended RANS equations solver was used to perform additional simulations for this ship advancing at selected speeds in equivalent regular design waves that represent wave conditions considered critical for structural design. Except for the very forward part of the ship, long-term BEM-based predictions of wave-induced hull girder torsion did not exceed rule values. Comparative BEM and RANS predictions of hull girder torsion differed significantly, underlining the need to validate the predictions systematically.