1. Trondheim Tekniske Fagskole The “Design Wave Philosophy’’ *****Calculation of the design wave ***** Wave forces on semi-submersible platforms Wave forces and bending moments in FPSO-ships Platform movements in large waves Examples of heavy weather damage What is a Rogue Wave ? Why, where and when ? Shall we design against Rogue and Freak Waves ? What can a platform master do against Rogue and Freak Waves ? Remote-sensing of sea conditions Search And Rescue and emergency operations Decision making in an emergency Calculation of the design wave

2. Trondheim Tekniske Fagskole Calculation of the design wave

3. Trondheim Tekniske Fagskole Calculation of the design wave Data collection Extrapolation to extremes Examples

4. Trondheim Tekniske Fagskole Data sources buoy - satellite - hindcast model

5. Trondheim Tekniske Fagskole Data sources Field measurements: costly short duration local validity often only synthetic parameters reasonably good…

6. Trondheim Tekniske Fagskole Data sources …but should one trust them at all times ?

7. Trondheim Tekniske Fagskole Data sources …but should one trust them at all times ?

8. Trondheim Tekniske Fagskole Data sources Satellite only significant wave height no wave direction very unreliable period estimates sparse sampling both in time and space yet available almost anywhere

9. Trondheim Tekniske Fagskole Data sources hindcast models costly better calibrated in common conditions than in extreme ones good length databases no individual wave data

10. Trondheim Tekniske Fagskole Data sources Reconciliation problems when merging buoy - satellite - hindcast model

11. Trondheim Tekniske Fagskole Calculation of the design wave Data collection Extrapolation to extremes Examples

12. Trondheim Tekniske Fagskole Database: 20 years of data available from Frigg QP platform in the North Sea

13. Trondheim Tekniske Fagskole Database: 1979-1989: mostly 3-hourly measurements, many time-series available. 1991-1999: mostly 20-minute statistics, only reduced parameters

14. Trondheim Tekniske Fagskole Calculation of the design wave Empirical distribution and duration it represents

15. Trondheim Tekniske Fagskole Calculation of the design wave Fitted parametric model

16. Trondheim Tekniske Fagskole Calculation of the design wave Approximated model for maximum over observation duration

17. Trondheim Tekniske Fagskole Calculation of the design wave Extrapolation to planned duration

18. Trondheim Tekniske Fagskole Calculation of the design wave Data collection Extrapolation to extremes Example The Port-Louis case

19. Trondheim Tekniske Fagskole The Port-Louis case

20. Trondheim Tekniske Fagskole The Port-Louis case Build a wharf for a coal power generation facility

21. Trondheim Tekniske Fagskole The Port-Louis case Hs less than 1 m more than 99.7% of the time, yet once in a while...

22. Trondheim Tekniske Fagskole The Port-Louis case

23. Trondheim Tekniske Fagskole The Port-Louis case 6 in 40 years, and Port Louis was sheltered on some of them

24. Trondheim Tekniske Fagskole The Port-Louis case Variables not “i.i.d.” => 2 options: cheap one, consider a nearby more exposed location and define risk attenuation from that location expensive one, run hindcast again sending synthetic hurricanes into the area