Milestone trial proves fully automated cable control for hybrid vessels operating on dynamic positioning
Stillstrom by Maersk has successfully proven that offshore vessel charging can be fully automated, removing one of the practical barriers to hybrid and electric support vessels operating on dynamic positioning (DP) in offshore wind farms.
Connecting a vessel to an offshore power source while it holds position on DP means managing a moving cable safely, a task that has traditionally needed manual oversight and carries cost and risk. A trial of the Stillstrom Offshore eCharger (SOeC), witnessed by DNV as part of its technology qualification process, demonstrated Stillstrom's cable control system managing cable automatically, from initial connection through to the vessel returning to position.
The trial was performed in collaboration with offshore wind vessel operator ESVAGT, and Semco Maritime, a long-term development partner for Stillstrom, which helped set up the test from its yard in Esbjerg, Denmark.
During the trial, the charging connector was deployed to the vessel from a height of 15.5 metres, representative of the wind turbine or substation height at which a Stillstrom system would be mounted in the field. The cable reel on the tower held 125 metres of cable, with the technology automatically paying out more cable as the vessel moved further away and reeling it back in as it returned, maintaining a constant cable profile throughout.
The trial tested five elements - control system performance for automated cable control, RTK GPS as a position reference for that control, synchronised line speed between the tower-mounted cable reel and the electric pull-in winch placed on the vessel, the user interface and logging features for monitoring and data collection, and the system's behaviour under realistic yard conditions.
'Cable control is one of the trickier parts of offshore charging to get right, and this successful trial showed our system safely managing it automatically as the vessel moves, and communicating reliably well beyond our planned range.
None of this happens without having the right partners in the room, and ESVAGT and Semco Maritime have helped drive this forward. This is another meaningful step, giving the sector further confidence in our offshore power and charging solution as we move towards full-scale deployment,' said Kristian Borum Jørgensen, CEO of Stillstrom.
Stillstrom has been pioneering offshore power and charging solutions to decarbonise the maritime sector from its bases in Copenhagen and Aberdeen and is on the cusp of commercial rollout. This latest assessment followed yard and harbour trials carried out in 2024 and a dry test completed in February 2026. The next step is a more integrated test involving an SOV and the full system, ahead of an eventual sea trial for final certification, which may also serve as the technology's first deployment.
Source: Stillstrom
