Ulstein books first X-Stern order

JANUARY 13, 2015 — Norway's Ulstein Verft has signed a shipbuilding contract with Hamburg, Germany, based Bernhard Schulte for two vessels that will be the first to be built at the shipyard for the offshore wind industry — and the first vessels to incorporate the X-Stern hull form.

The two 88 m x 18 m service operation vessels (SOVs) are being built to the Ulstein SX175 design developed by Ulstein Design & Solutions, with the final detailed arrangements and equipment being developed and specified in cooperation with WINDEA Offshore GmbH & Co. KG, Bernhard Schulte's affiliate for offshore wind projects.

"We have had a close and very good cooperation with the owner during the process and are very pleased that WINDEA chose this innovative solution, and that the first vessels with X-Stern will be built," says Kolbjørn Moldskred, Sales Manager Offshore Wind at Ulstein Design & Solutions.

The vessels can accommodate 60 people in single cabins, of which 40 are for wind turbine service technicians.

An offshore wind service vessel's most important task is to stay positioned on DP close to the turbines, with as little movements as possible, in order to provide a safe transfer for the technicians from the vessel through a heave compensated gangway to the turbines.

In the Ulstein SX175 significant effort has gone into the optimization of the vessel's movements in order to ensure the safe transfer of technicians and equipment to the wind turbines.  Another major focus has been the welfare of the technicians living on board with the aim being to position cabins and facilities where the vessel's movements are lowest.

The X-Bow, the X-Stern and the integrated DC-based common main drive system, with variable rpm control of the diesel engines for power and propulsion system, are essential design features.

The X-Stern design is intended to increase operability through positive effects on station keeping, wave response, comfort and safety in harsh conditions.

An X-Stern vessel can stay on position in harsh weather with the stern towards waves, wind and current. Ulstein says that positioning the X-Stern rather than the bow towards the weather will be the Captain's natural choice for vessels where the best possible motion characteristics are vital.

The X-Stern has several of the same characteristics as Ulstein's now well proven X-Bow. Ulstein says that the X-Stern's gentle displacement reduces acceleration, pitch and heave, it improves comfort and safety, and the operational window is increased. There will be no sea on deck due to the stern shape and enclosed nature of the aft deck.

"Delivery schedule reliability was our number one priority when choosing the shipyard. We considered several yards worldwide, but Ulstein Verft was our final choice. They have a solid reputation, not only on keeping to delivery schedules, but also of delivering innovative vessels of high quality," says Matthias Müller, Business Development Director at Bernhard Schulte.

Christian Brozinski, Business Development Manager at WINDEA, says: "After working together very closely and successfully in the design phase with Ulstein Design & Solutions, we are pleased to continue the project with Ulstein by choosing their shipyard. The collaborative design team consisting of Ulstein, WINDEA and Bernhard Schulte created a vessel which perfectly fits the needs of the offshore wind industry."

"Sustainable growth is essential for Ulstein and we have previously delivered ship designs within the renewable energy segment. We look forward to cooperating with WINDEA, who are a new and interesting partner for us," says Ulstein Group CEO Gunvor Ulstein.

"These are the first service operation vessels for the wind industry to be built at the yard and we look forward to delivering two state-of-the-art vessels in Q2 2016 and Q1 2017," says Ulstein Verft Managing Director Kristian Sætre.

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