TWIN X-STERN for walk-to-work services

Is a bow really a necessity for large ships? A heightened stern, the TWIN X-STERN, can operate either way, thus facilitating on-site DP positioning. This idea was nominated for the Innovation of the Year Award at the OSJ Conference 2016.

When the vessel’s main function is walk-to-work (W2W) services in the offshore renewable sector, a heightened stern can operate either way, thus facilitating on-site DP positioning. This is the idea behind the TWIN X-STERN concept vessel from ULSTEIN, which also includes new thoughts on propulsion, bridge, gangways and cranes.

With an X-STERN at each end, the vessel is symmetrical, with a continuous large work deck and cranes on either side of the bridge. The X-STERN is heightened by one deck and gives shelter to the deck area. The large deck space can be used for transporting equipment, containers and spare parts.

"By moving wind farms further from shore, the turbines can increase in size. The TWIN X-STERN vessels will be ideal for maintaining large-scale wind farming activities far from shore." Øyvind Gjerde Kamsvåg, Chief designer

Key benefits


Perform the same work on either side, and keep position with either end towards wind turbines.


The two smaller main propulsion units provide the same power as one large unit but with increased fuel-efficiency.


Reduce pitching and increase operability in a head sea while maintaining gentle movements for the crew’s well-being.

The asymmetrical bridge can be made of composite material and is placed midship, diagonally above the work deck. The operating bridge is placed as a lookout platform on both the starboard and port sides, close to the ramp on either side, giving a full overview of the nearest ramp as well as the complete work deck area. The vessel can be equipped with a safe transferral ramp on both the star board and port side of the bridge. Additionally, a large W2W ramp for oil and gas rigs can be integrated into the vessel for more flexibility. The helideck is placed on top of the bridge, where the movements are at the lowest.

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