Effect of bow flare on the vertical ship responses in abnormal waves and extreme seas

Abstract

Linear to fully body nonlinear numerical methods based on strip theory are used to analyze the vertical responses of a bulk carrier, containership and a passenger ship. The ships are categorized based on their bow flare angles and the effects of the bow flare variation on the vertical responses are investigated numerically. The numerical ship responses in abnormal waves and extreme sea conditions are also compared with the measurements in a wave tank. The linear method, which does not take account of any body nonlinearity, is able to predict the vertical responses of the conventional ships with large block coefficients, like Bulk carriers and tankers, even in extreme sea conditions. However, pronounced bow flare induces strong nonlinearities in the vertical responses in rough seas and the linear or even partially body nonlinear methods are not enough for accurate calculations in those conditions. The extreme loads acting on the ships are also compared with the rule vertical bending moment.