Stillstrom by Maersk has demonstrated fully automated cable control during offshore vessel charging, addressing one of the practical obstacles to running hybrid and electric support vessels on dynamic positioning inside wind farms.
Connecting a vessel to an offshore power source while it holds position on DP means managing a cable that is constantly moving. That task has traditionally required manual oversight, adding both cost and risk. In a trial of the Stillstrom Offshore eCharger, witnessed by DNV as part of its technology qualification process, the cable control system handled the cable automatically from initial connection through to the vessel returning to position.
The trial was run with offshore wind vessel operator ESVAGT and Semco Maritime, a long-term development partner, which hosted the test at its yard in Esbjerg, Denmark. The charging connector was deployed from a height of 15.5 metres, representative of the turbine or substation height at which a Stillstrom unit would be mounted in the field. A tower-mounted reel held 125 metres of cable, paying out as the vessel moved away and reeling back in as it returned while maintaining a constant cable profile.
Five elements were tested: control system performance for automated cable handling, RTK GPS as a position reference, synchronised line speed between the tower reel and an electric pull-in winch on the vessel, the user interface and logging functions, and 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,” said Stillstrom CEO Kristian Borum Jørgensen.
The company, founded in 2019 as a Maersk innovation project and spun out as an independent business in 2022, employs more than 30 people across Copenhagen and Aberdeen. The trial followed yard and harbour tests in 2024 and a dry test in February 2026. Next comes a more integrated test involving a service operation vessel and the full system, ahead of a sea trial for final certification that may double as the technology’s first deployment. For Baltic operators facing longer transits to increasingly distant sites, in-field charging is one of the few routes to keeping hybrid SOVs on battery power for a meaningful share of the working day.
