| Abstract | The design of a warship requires accurate predictions of sea loads in extreme wave conditions. Such loads are difficult to obtain from full scale measurements alone because the durations over which these conditions exist are short relative to the overall operational profile of the circumstances. In response to a requirement for data on ship structural behaviour in severe seas, a segmented flexible backbone model of a modern Canadian frigate was built and tested in severe regular and irregular wave conditions. Linear frequency domain predictions are shown to give good agreement with experimental wave-induced oscillatory motions and sea loads up the maximum tested wave steepness of 1/15. Nonlinear effects induce non-zero mean vertical bending moment at midships, leading to sag/hog ratios significantly greater than unity. Analysis of measured whipping responses in regular waves demonstrates that the induced vertical bending moment at midships can approach the wave-induced oscillatory moment in magnitude at higher operating speeds and wave steepnesses. |
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