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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
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Trondheim Tekniske Fagskole Calculation of the design wave
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Trondheim Tekniske Fagskole Calculation of the design wave Data collection Extrapolation to extremes Examples
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Trondheim Tekniske Fagskole Data sources buoy - satellite - hindcast model
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Trondheim Tekniske Fagskole Data sources Field measurements: costly short duration local validity often only synthetic parameters reasonably good…
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Trondheim Tekniske Fagskole Data sources …but should one trust them at all times ?
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Trondheim Tekniske Fagskole Data sources …but should one trust them at all times ?
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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
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Trondheim Tekniske Fagskole Data sources hindcast models costly better calibrated in common conditions than in extreme ones good length databases no individual wave data
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Trondheim Tekniske Fagskole Data sources Reconciliation problems when merging buoy - satellite - hindcast model
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Trondheim Tekniske Fagskole Calculation of the design wave Data collection Extrapolation to extremes Examples
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Trondheim Tekniske Fagskole Database: 20 years of data available from Frigg QP platform in the North Sea
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Trondheim Tekniske Fagskole Database: 1979-1989: mostly 3-hourly measurements, many time-series available. 1991-1999: mostly 20-minute statistics, only reduced parameters
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Trondheim Tekniske Fagskole Calculation of the design wave Empirical distribution and duration it represents
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Trondheim Tekniske Fagskole Calculation of the design wave Fitted parametric model
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Trondheim Tekniske Fagskole Calculation of the design wave Approximated model for maximum over observation duration
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Trondheim Tekniske Fagskole Calculation of the design wave Extrapolation to planned duration
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Trondheim Tekniske Fagskole Calculation of the design wave Data collection Extrapolation to extremes Example The Port-Louis case
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Trondheim Tekniske Fagskole The Port-Louis case
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Trondheim Tekniske Fagskole The Port-Louis case Build a wharf for a coal power generation facility
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Trondheim Tekniske Fagskole The Port-Louis case Hs less than 1 m more than 99.7% of the time, yet once in a while...
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Trondheim Tekniske Fagskole The Port-Louis case
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Trondheim Tekniske Fagskole The Port-Louis case 6 in 40 years, and Port Louis was sheltered on some of them
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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
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