OHT Semi-submersible vessel.

Spot-on design development in offshore renewables

​With the introduction of the Alfa Lift design, Ulstein has provided the market with the next step in heavy lift vessel design. With Offshore Heavy Transport (OHT) as launching customer, this heavy lift transport and installation vessel is set to be the new benchmark in the offshore renewables and installation market.
19 October 2018

The first vessel, with options for up to another 3 units, will be constructed by China Merchant Heavy Industry (CMHI).

What makes this dynamically positioned, 48,000 DWT vessel exceptional is the ability to perform heavy lift crane operations with the main deck submerged.

The patent-pending design combines the benefits of a semi-submersible transport vessel with a large, 3,000 mt lifting capacity main crane from Liebherr.

The vessel's capabilities match the future requirements of the offshore wind industry, allowing her to transport and install up to 10 x 1,500t ultra-large jacket foundations or 11 x 2,000t XXL monopiles plus transition pieces for the largest anticipated Wind Turbine Generators.

«We started the development of the ULSTEIN Alfa Lift idea back in 2015 with the driver to increase the safety of submerged operations and at the same time increase the operability window for subsea installations using a crane,» says Edwin van Leeuwen, managing director at Ulstein Design & Solutions BV.

«Creating a new design with this combination of functionalities has its own, specific challenges. But then again, challenges are what we are good at!,» states van Leeuwen.

'This vessel's design is a direct hit'

Torgeir E. Ramstad, CEO at OHT says: «It is great to work with such capable people. When we approached Ulstein with our intended strategy to enter the offshore renewables market and the idea of adding crane capacity to a semi-submersible heavy lift transport vessel, Ulstein presented their Alfa Lift solution on the spot.»

He continues: «That was a direct 'hit', as it allows us to enter the installation market, at the same time expanding on our capabilities in OHT's core market.»

2018 yard contracts in offshore wind

In 2018, Ulstein's own yard, Ulstein Verft, secured 3 construction contracts related to offshore wind:
- 1 SOV for Acta Marine
- 1 SOV for Bernhard Schulte
- 1 cable lay vessel for Nexans

The SOVs (Service Operation Vessels) are designed by Ulstein, and feature the branded hull solutions X-BOW® and X-STERN®.

The X-BOW® has a look that differs from the more conventional bow designs.

But there´s much more to it than the looks: Instead of simply rising on the waves and then dropping with tremendous force, the X-BOW is able to absorb the force more consistently across its surface ? enabling the ship to remain more stable during poor weather conditions, increasing comfort for passengers and crew alike. And because it uses less fuel to get through the waves, it also helps to save energy.

The next development, the X-STERN, has successfully proven itself in practice by increasing the operational window of service operation vessels. It is also suitable for other vessel types like cable layers and has so far been introduced on totally 6 SOV designs.

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In 2023, Ulstein Group recorded revenues of NOK 1.4 billion and an operating profit of NOK 49 million. The knowledge and experience Ulstein have gained through more than a hundred-year history have created a dynamic and flexible organisation that we now benefit from in the transition to a greener and gradually more fossil-free future.

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Kolbjørn Moldskred

Sales Manager Newbuild

Ulstein Verft AS

Ulstein Design & Solutions B.V.