Page 54: of Marine Technology Magazine (June 2012)

AUV Arctic Operations

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vessel Spirit to the power management station ashore, and to patch in each wind turbine to the offshore hubs ? or subsea junction boxes in layman?s terms. The main export power cable has a diameter of 208mm and weighs over 80kg/m in the water. Sea ex supplied over 3km of SeaSerpent cable buoyancy system in 50m and 100m lengths, each section delivered on a steel deployment reel. SeaSerpent was the perfect product for this installation due to the extremely shallow water (0m to 6m over 3km) and be- cause due to tidal variations, the cable route dried out for 8 hours in every 12. SeaSerpent allows for a high rate of lay meaning the 4 opera- tional hours were used to maximum ef ciency. At the offshore end of the power cable a hub was installed in the midst of the turbine array, with cable spurs running to each turbine. As the spurs approach each turbine, they cable lay vessel performs a zig zag course, laying the cable in what is know as a lazy ?S? over the last 500m or so. After detailed engineering analysis with Visser & Smit, Sea ex were asked to provide 3 x 120m lengths of 33kg/m SeaSerpent and 25 x 250kg Air Lift Bags, not to lift the cable, but to lighten it in preparation for the cable end to be winch up inside each turbine?s J-Tube. During the winching operation, Hughes Sub Surface Engineering divers were employed to peel off the Sea- Serpent and remove the 250kg Air Lift Bags at the J-Tube?s bell mouth.Vessel Floatation During a power outage, The Jean Ricciardi, a 25-m, 250-gt vessel ran aground and damaged her hull resulting in her sink- ing close to Sete harbor, in France. Due to the water depth and the close proximity to the harbor entrance a rapid solution was required. The local diving & salvage contractor, Prodive of Monaco, contacted Sea ex to supply the necessary equipment - 12 x 20t ALB (Air Lift Bags). The bags were packed and dispatched from stock the same day from Sea ex head quarters on the Isle of Wight and ar- rived on site two days later. The salvage was completed by the contractor within a week of the call to Sea ex and the Jean Ricciardi has now been safely removed from the water to be broken up for scrap. The Sea ex buoyancy range includes;  Air Lift Bags (ALB?s)  In atable Buoyancy Units (IBU?s)  Mono Buoyancy Units (MBU?s)  SeaSerpent Cable Buoyancy System (SS)  Kraken Pipeline Buoyancy System (KS)  WaterLoad Bags (WLB?s)  Lifeboat Testing Bags (LBTB)  Load Cells (LC)Case Study MTR #5 (50-64).indd 54MTR #5 (50-64).indd 545/31/2012 3:17:11 PM5/31/2012 3:17:11 PM

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