Wind turbines and ships may not seem to have an obvious connection – unless you need to service offshore wind turbines, when an especially seaworthy, flexible and manoeuvrable vessel really comes into its own
The 2017 Offshore Renewables Award was sponsored by F3O Offshore Services and is awarded to a company, project or product that has made a significant contribution to the development of the offshore renewables market during 2016. The winner was an innovative service operation vessel, Windea La Cour, the first ever vessel with the Ulstein X-STERN, which was designed and built by Ulstein in Norway for Bernhard Schulte Offshore and contracted by Siemens Wind Power. The vessel is currently in service at the 600 megawatt Gemini offshore windfarm in The Netherlands.
Windea La Cour has made a significant contribution to the offshore renewables market, but its significance is far wider, being the first vessel in any market with the X-STERN. In addition to the X-STERN it also has the X-BOW shape from the Norwegian vessel designer and builder, and both optimise the ship for operations on offshore windfarms, not least because with an X-STERN the vessel’s operator avoids losing time by continually having to turn the vessel when relocating. Unlike any other vessel, which has a bow designed to pass easily through waves, with minimal resistance, this ship is also designed to reverse through them, stern first.
“The X-STERN hull shape allows the vessel to be positioned with the stern facing towards the weather instead of the bow only,” Matthias Müller, managing director of Bernhard Schulte Offshore explained. “This gives the vessel improved weather resilience, greater operability and reduces power and fuel consumption while in dynamic positioning mode next to a wind turbine.”
Studies show that vessels servicing offshore wind turbines operate astern at least 50-70 per cent of the time after arriving at windfarms. Having the X-STERN makes them much better suited to doing so and confers on the vessel the same benefits as the X-BOW.
Hence, Windea La Cour has twice the benefits of the X-shape hull configuration. Bow first the vessel was found to have a maximum speed of 13.95 knots when on trials; stern first, the vessel could make 12.1 knots, so not only is especially manoeuvrable, with excellent seakeeping and performance in dynamic positioning mode, but it can make good speed whether under way bow or stern first. Flexibility is thus another key advantage of the combined X-BOW and X-STERN vessel. Comfort levels on board are better than they would be on a conventional vessel and noise, vibration levels and slamming are reduced.
SOVs provide a means of transport for windfarm technicians but are also hotels for them, and provide a warehouse and a workshop at sea. They need to be fast, reliable and safe, and able to transport large quantities of spare parts and tools. Like most other SOVs, Windea La Cour has a walk-to-work offshore access system, a motion compensated gangway to enable maintenance teams to walk from the vessel to the turbines in wave heights of up to 2.5m or more. The crane on the SOV can hoist equipment and spare parts from the vessel onto the wind turbine platform.
For client Siemens, the above-mentioned advantages of the X-STERN ship translate into operational efficiencies and help the company’s customers realise optimal performance from their turbines.
“Siemens is at the forefront of introducing the SOVs that are being constructed specifically for offshore wind service operations,” said the company, noting that it had taken an active role in specification of vessel, with emphasis on safety and improving efficiency.
Also shortlisted for the award were:
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