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SURVEY VESSELS


INNOVATION IN SURVEY VESSELS


N-Sea is known for its innovative work as an independent offshore subsea contractor, specialising in inspection, maintenance and repair services for the renewable and energy industries. The company operates a fleet of specialised multipurpose vessels which are equipped with state-of-the- art systems and equipment as well as supporting a wide range of subsea operations.


PROJECT CASE STUDY A recent project utilised four vessels including the Noordhoek Pathfinder, a survey and offshore support vessel, to complete an unexploded ordnance (UXO) survey, ID and disposal campaign for the TenneT project, BorWin3.


The Noordhoek Pathfinder is equipped for ROV, diving and survey projects with integrated air diving systems, vessel- mounted USBL, multibeam, sub-bottom profiler, ROV, ROTV and accommodation for 40 people. The vessel’s speed and endurance enable a highly efficient range of operations, globally.


BORWIN3 PROJECT


For the BorWin3 project, transmission system operator TenneT built a grid connection system to connect wind parks in the North Sea with the high-voltage grid onshore. N-Sea’s work scope involved surveying the seabed to identify and remove undiscovered explosive devices along the cable route of BorWin3.


The cable corridor started in very shallow water mudflats for a 12 nautical mile zone, north of Borkum in Germany. This was an extremely challenging environment known not only for its shallow waters, but also high currents and continuously moving sandbanks.


The survey campaign undertaken by N-Sea comprised a geophysical survey (multibeam, Side Scan Sonar (SSS), Sub Bottom Profiler (SBP) and Magnetometry) of 137 targets within the main cable corridor and adjacent anchor corridors, totalling almost 2000km.


RESULTS


The investigation element of the project resulted in three positively-identified explosives; two sea mines and one grenade. The sea mines were destroyed on site, with N-Sea coordinating the operation under supervision of an explosive ordnance disposal service.


Requiring a more accurate identification, the grenade disposal was carried out on board a separate vessel, through use of a mobile x-ray machine.


SAFE PROJECT COMPLETION Despite the challenges documented above, the project was completed safely and effectively with no incidents, and reflected N-Sea’s ability to always provide safe, sound and swift solutions.


N-Sea


FEATURE SPONSOR


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www.windenergynetwork.co.uk


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