A ‚Äö"Reverse Engineering" approach to investigate slamming loads on large high-speed wave piercers is used in conjunction with trials data and finite element analysis. Trials data are used to develop the loading conditions during severe slamming events in terms of the vessel motions and immersion. The underlying wave loads are applied to a global FE model, in addition to a complementary slamming load. The longitudinal and transverse slam load distribution was based on pressure measurements during model tests. The load location and magnitude were then systematically changed until the best match between trials and FE strains was achieved. The results show that the comparison method with trials is critical and suggests that FE dynamic analysis is required to fully understand and develop realistic interpretation of slamming loads during trials.