The October 4 2018 COPRI Houston Conference lecture Breakwater Caisson Design was presented a few days before the first Nador Caisson was loaded out in Morocco.

This video illustrates a success story.  The loading out the 3,000 tonne caisson (that had been slipformed on land) is shown onto a semi-submersible barge.  The barge is towed to relatively deep water and ballasted down, until the caisson can be floated off.  The caisson is then towed to a moderate water depth where it is ballasted down and stored until all caissons are ready for final installation.

All phases of the operation required naval architecture calculations for the hydrostatic stability of the caisson and barge. About 100 Caissons make up the breakwater for the new harbor at Port Nador.

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Sewol Salvage: Stewart Technology Associates worked as Technical Advisors to Shanghai Salvage Company using STA software and were responsible for all dynamic analysis of the complex lifts in the open ocean environment.  All lifts are dynamically sensitive and involved cutting edge marine salvage dynamics. Analyses were performed with waves in the time domain using FEA (OrcaFlex).

Marine Salvage Dynamics of Sewol Salvage raised with ZPMC 12,000 ton floating crane and 1,200 ton lifting frame.

32 HMPE upper slings, 8 balance slings, 34 pairs of steel lower slings.

Fully coupled 6 DOF time-domain dynamic analyses in OrcaFlex with diffraction forces on the Sewol and ZPMC crane barge.  All individual sling tensions computed during all stages of the Sewol Salvage.

Sewol wreck transfered to semi-submerged floating dry dock in open ocean.  OrcaFlex time domain dynamic analysis of three main vessels, lifting frame and all slings.

The following video describes how STA has examined the issues of unusually low freeboard and trapped water on the pontoon deck.

The video provides a description of how OrcaFlex is used to cope with time domain calculations of the wave motions of the floating dry dock when the deck becomes submerged and the buoyancy of the wing tanks is of critical importance.

More details of the accident can be found at:

gCaptain

Wikipedia

The  portfolio item below provides a short OrcaFlex Tutorial with a Mooring Analysis example.

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