A study of slamming events in conditional waves is presented in this paper. The ship is sailing in head sea and the motion
is solved for under the assumption of rigid body motion constrained to two degree-of-freedom i.e. heave and pitch. Based on
a time domain non-linear strip theory most probable conditional waves are generated to induce short term extreme responses
of 4500 MNm sagging and hogging vertical bending moment (VBM) amidships on a modern 9,400-TEU post-Panamax container
ship and 3000 MNm (sag) on a Panamax container ship. The results of the strip theory are compared to the results of free
surface NS/VOF CFD simulations under the same wave conditions. In moderate seas and no occurrence of slamming the structural
responses predicted by the methods agree well. When slamming occurs the strip theory overpredicts VBM but the peak values
of VBM occurs at approximately the same time as predicted by the CFD method implying the possibility to use the more accurate
CFD results to improve the estimation of slamming loads in the strip theory through a rational correction coefficient.