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Friday, June 18, 2021 

Ulstein has developed a ship with two sterns and propellers in each corner, which is claimed to be ideal for offshore operations requiring continuous positioning.

“The Twin X-Stern is extremely manoeuvrable, comfortable to be on board and very environmentally friendly,” said Øyvind Gjerde Kamsvåg, Chief Designer, Ulstein Group.

Most ocean vessels still run on fossil fuels, accounting for over 1bn tons of global greenhouse gas emissions a year. Despite incentives to promote more environmentally friendly vessels, international shipping emissions are said to have increased by 9.6% from 2012 to 2018. More radical steps must be taken if the industry is to achieve the IMO target of a 50% reduction in annual emissions by 2050.

Ulstein Group has a clear ambition to achieve zero-emission offshore operations by 2050, with innovative hull designs, including the Twin X-Stern.

“The key advantage of the hull is its ability to stay in position. The secret lies below the waterline. Twin X-Stern has propellers in each corner, which provide maximum manoeuvrability. The hull also provides major fuel savings. We’ve received feedback from the industry that the sister patent X-Stern result in up to 60% less power,” said Kamsvåg.

The Twin X-Stern concept has been in development since 2015, and is now commercially available on a range of vessels, including those servicing offshore wind turbines.

“By having excellent performance in either direction, you avoid having to turn the ship to follow weather changes. This is traditionally required maybe 50% of the time, depending on the operation being performed. You save an enormous amount of time by not turning the vessel. The total energy savings are significant compared to traditional hulls,” said Lars Ståle Skoge, Commercial Director, Ulstein Design & Solutions.

Vessels with Ulstein’s innovative hulls exhibit reduced motion in the water, avoiding the slamming from waves experienced by vessels with traditional hulls. This also extends the lifetime of onboard equipment as it is not exposed to strong vibrations and impact.

“It’s a completely different experience to be on board. It’s built to operate in very strong currents and is less limited by weather conditions. Twin X-Stern is in the same family as our other two revolutionary hulls, X-Bow and X-Stern, and provides similar benefits, just in a different set-up optimised for the offshore wind segment,” said Kolbjørn Moldskred, Sales Manager, Ulstein Design & Solutions. “Offshore wind is a major growing market. Our new hull has the potential to service more wind turbines per day than other hulls. It’s optimised for exactly these types of positioning operations.”

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