The Norwegian offshore vessel operator Olympic has now taken delivery of the second of the unique vessels, Olympic Notos, from compatriot shipbuilder Ulstein after realising these significant fuel savings in dynamic positioning with the previously delivered sister vessel Olympic Boreas during operations for BP off the UK, prior to starting work on an offshore wind project in the UK North Sea, according to Ulstein's release.
These are the first CSOVs to employ the TWIN X-STERN system, with four main thrusters fore and aft in a symmetrical dual-stern hull, allowing flexible operability in dynamic positioning (DP2) mode. This is complemented by diesel-electric propulsion with variable speed, hybrid battery power, energy storage and smart energy management to maximise fuel efficiency.
Based on the ULSTEIN SX222 design by Ulstein Design & Solutions AS, the vessels are intended for work in the offshore wind and oil & gas segments, with a length of 89.6m and beam of 19.2m, and accommodation for 126 people in 91 cabins. They are also equipped with a heave motion-compensated gangway system for efficient transfer of personnel and cargo at variable landing heights.
The implementation of several technical measures onboard the vessel has resulted in a power demand of only 250-300 kilowatts under certain conditions. At such low power demands, operating at variable speed enables a more optimal operation of the engine – as opposed to operating at constant speed – and results in significantly lower energy consumption per kWh. Consequently, the ability to operate the engine at variable speed, combined with the technical measures and the overall ship design, has enabled the Olympic Boreas to consume only 2.7 tonnes of fuel per 24 hours during a week of DP operations, which is approximately 50% less than other sailing CSOVs.