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Working under high voltage

Even on a rough sea, a crane has to be able to lower loads of up to 120 tons into the water, accurate to the tenth of a metre

She was ready earlier this year: the Seven Atlantic, an ultra modern support vessel for divers in the North Sea. Responsible for the electrical wiring is Croon-Bakker Sliedrecht, who during the test phase could rely on the services of Energyst CAT ® Rental Power.

The recent delivery of the Seven Atlantic Subsea 7 to its owner meant the next step in a truly epic project for IHC Merwede Shipyard in Hardinxveld-Giessendam. In a relatively short time the company has produced two so-called pipe laying vessels – the Seven Oceans and the Seven Seas - and has completed project number three with the transfer of the Seven Atlantic. They are currently already working on the fourth ship, which as of yet remains nameless. Starting this year, the ships will perform their duties in the deep oil fields in the North Sea.

The Seven Atlantic is known as "Diving Support Vessel", and is equipped with the latest techniques to enable divers to perform work at depths of several hundred meters.

Safety first

Due to the specific nature of these works, the equipment on board the Seven Atlantic has to be highly reliable. Only then can a crane lower loads of up to 120 tons into the rough waters, accurate to the tenth of a metre. Therefore, all installations, as well as the vessel’s electrical system, are tested in preparation, a process which actually begins when the ship is still being designed. "Energyst locates the Vessel Identification Numbers of ships to be built about two years in advance, in order to understand the market long term," states Frank King, General Manager of Energyst Benelux. "We are dealing with specialist equipment which is not available to many parties. That is why it is good to know ahead of time if clients are going to need these materials. Once the job is confirmed, we will consult with the installer months in advance to determine the specifications and technical requirements. In the case of the Seven Atlantic we liaised with Bakker Sliedrecht, with whom we also refined the logistical plan of action. The test phase is only a small step in the entire construction of a new ship, but it is crucial to the final quality."

Intensief samenwerken
Even though it is only a small step in the building process, in practice it is quite complex. For a start, the propulsion of the Seven Atlantic is state-of-the-art: six diesel engines, each powering a generator, which in turn control six different propellers and power the control board through their switchboards. The ship also has a modern Dynamic Positioning System, which automatically keeps the ship in place using sensors and DGPS.

"That's a lot to test, you're dealing with a total capacity of over 8,000 kW at 6,600 volts. What’s more, the ship also has to fulfil the DP3-standards", explains Werner Boer, system integrator with Bakker Sliedrecht. "That means, for example, that the ship needs to remain in position, even if one engine fails, which is why the three engines are separated. In order to be able to run all the tests intensively and under full load, we needed two load banks for several weeks.
That is when you notice the benefits of dealing with a company like Energyst. Together we have prepared the entire project extensively, and as companies we worked closely together for a short period of time.

That is why the transport and the placement of the four 20-tonne containers on board happened without any problem. That's encouraging, especially because a lot of different parties have to work together for the first test days. We built the test installation in cooperation with Energyst, and then we could carry on independently, using our own experience. But it is good to know that in case of a malfunction - which we did not experience – you can reach your supplier day and night."

Seven Atlantic in figurers:
Total weight:    11.885 tonnes
Length:    144,85 metres
Width:    26,00 metres
Draft:    8,00 metres
Propulsion:    6 diesel engines a 3.300 kW per engine
Max. Speed:    13,6 knopen
Crew:    150
Number of divers:    24
Specialties:    helipad sick-bay Dynamic Positioning System  Well-treatment system
 

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