It’s Fun Fact Friday and we’re going to take a quick look at the Neptune jack-up, the world’s largest jack-up vessel. What exactly is a jack-up? It’s a barge with support legs that can be raised or lowered to stand above the water. They can be self-propelled and after arriving at their destination, they can jack their legs down to the seafloor to raise the barge, creating a platform that is unaffected by waves and, for the most part, wind. After the sea legs are put down, they are pre-loaded to ensure the vessel does not move as work is being performed. They are commonly used for offshore construction, exploratory drilling, and wind farms.
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Neptune side view with legs retracted. Image credit: DEME.
Neptune is the world’s largest jack-up at 60.25 meters long, 38 meters breadth, and 6 meters of depth. It has a hydraulic positive engagement jacking system capable of supporting 6,000 tons. The legs are 80 meters long and extendable to 92 meters if needed. The rig has a total power of 8,970 kW and propulsion is provided by four azimuth thrusters at 1678 kW each. It has a Kongsberg DP2 dynamic positioning system for precise maneuvering and safety and Huisman provided the 600 ton crane. Impressive specs for sure, but why build such a large jack-up? Mostly for offshore wind farms.
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Neptune installing an offshore wind turbine. Image credit: DEME.
Belgian owners and operators GeoSea, an ancillary of the DEME conglomerate, wanted a unique vessel that could handle large installations. They went to IHC Merwede, a Dutch marine engineering and construction firm, and the vessel was completed in only one and a half years, an incredible feat for such a huge project. It set sail in 2012 and was certified as a Green Passport ship by ABS shortly after. It’s first operation was completing some of the later stages of a wind farm near Belgium, installing 48 turbines off the coast for the C-Power wind farm. The Huisman crane was specially designed for wind turbine construction and features “a full electric variable frequency drive system, a low overall construction weight and a small minimum operating radius”, according to gCaptain. Major equipment like hoist winches are in the enclosed crane house, better protecting them from the marine environment.
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Neptune top view. Image credit: DEME.
For more information on different types of jack-up vessels and the work they do, check out our article on how jack-ups work.
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