1. Wave Impacts due to Steep Fronted Waves Bas Buchner and Arjan Voogt

2. Damage to Schiehallion Bow Early storm, max ship response 2-6 hours later Estimated sea state: Hs=14m Tp=11s Severe steepness

3. Experiments on floating FPSO segmented bow

4. Schematic bow tests

5. Typical stages during impact

6. time step between profiles is 0.31 s MWL 6 m R4R5R3 R2 R1 R6 Spatial wave profile

7. Impact Time trace of wave steepness

8. d  dt wave time trace velocity d  dx steepness spatial wave profile Vertical Free Surface Velocity wave celerity

9. Time trace of d  /dt Significant wave impact time [s] Vertical free surface velocity [m/s]

10. d  /dt linear6 2 nd order10 measured12 measured 2 nd order linear Wave modeling to get d  /dt

11. Exceedance probability Vertical free surface velocity [m/s] Probability of Exceedance

12. Local impulse versus

13. Conclusions Wave steepness drives the impact Linear wave theory underestimates wave steepness 2 nd order wave theory results in improved prediction Good probabilistic models needed to predict extreme wave steepness