Theoretical Predictions of Springing and Their Comparison with Full Scale Measurements

The present paper considers a large ocean going ship with significant springing responses,which have made a large contribution to the fatigue cracking for certain structural details.Four dif - ferent theories for predicting ship responses and associated computer programs for predictions of springing are described.These theories represent four different approaches with various characteris - tics,e.g.linear,second-order,nonlinear,frequency-domain,time-domain,two-dimensional and three-dimensional,in calculating hydrodynamic loads and vibrations.The numerical programs,WASIM(DNV),SOST(DTU),SINO(CSSRC)and VERES(Marintek),have been well validated for ordinary ship responses.Assumptions regarding how the different programs are used in the present calculations are provided.Sensitivity studies are carried out and the main results are presented.A selected number of full-scale measurements with various sea states and headings used for comparison between numeri - cal results and the measurements are described.The comparison between simulated and measured high frequency(2-node vibration,denoted HF)and low frequency(wave-induced,denoted LF)stress - es in addition to some important observations are made.