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Offshore Wind Journal

Offshore Wind Journal

Walk-to-work support ship combines high-level operability and comfort

Fri 01 Sep 2017

Walk-to-work support ship combines high-level operability and comfort
Acta Marine’s newbuild has the Ulstein X-BOW and X-STERN hullform, conferring a high level of seakeeping and operability

July 2017 saw construction of the hull of Acta Marine’s Ulstein SX195 walk-to-work vessel pass the halfway mark at Crist shipyard in Poland


The completed hull is due to be towed from Crist to Ulstein Verft in Ulsteinvik, Norway, early in November 2017. Ulstein Verft will outfit the vessel and install equipment such as a motion compensated gangway and 3D crane. Delivery of the vessel to Acta Marine is slated for the end of Q1 2018.

The dynamic positioning class 2 (DP2) construction support vessel is primarily aimed at the offshore wind market but will also be capable of providing support from offshore oil and gas installations and is a new design from Ulstein Design & Solutions.

“We are expanding our services for offshore wind. The SX195 design with the X-STERN hullform, integrated walk-to-work gangway system, 3D motion compensated crane and accommodation represents our next step in responding to the market,” said Acta Marine managing director Rob Boer.

The company emphasised the vessel’s flexibility, winter workability, ability to provide safe transfer of people and cargo, optimised onboard logistics and high level of comfort for those on board the vessel. “All of the accommodation areas have been designed with the idea that rested personnel are productive personnel,” said the company. “A total of 80 cabins will provide best-in-class comfort levels, complemented by a buffet style restaurant, multifunction recreation room, sauna and fitness area. Smart connectivity options will allow personnel to bring their own devices onboard for access to the internet and video-on-demand services anywhere on board.”

The vessel is 93.4 m in length with a breadth of 18 m and can accommodate up to 120 people in 80 cabins. It will be equipped with a dynamic motion compensated gangway system from SMST in the Netherlands mounted on an integrated tower with height adjustment and a personnel/cargo lift.

Acta Marine’s new walk-to-work unit will also have an indoor cargo area of 500 m2 plus 500 m2 on deck and will be able to provide walk-to-work transfer of personnel and cargo in significant wave heights of up to 3.0 m. A total of 24 twenty-foot equivalent units can be stored on the two deck levels, allowing clients to take all the equipment necessary for longer offshore campaigns, giving the vessel the ability to operate without returning to port for approximately 30 days.

Describing the offshore access system it is providing for the vessel, SMST Designers and Constructors in the Netherlands – which is also providing a 3D motion compensated crane for the ship – described the system as “the first of its kind” and said it offers “a complete solution for offshore logistics”.

The gangway will be mounted on an integrated tower with height adjustment and a lift for personnel and cargo. It will provide a complete package with an elevator and access bridge trolley system. The trolley system will allow pallets carrying cargo to be transported onto the elevator, which can stop at different levels to optimise the performance of the vessel. The 3D motion compensated crane will have a lifting capacity of 6 tonnes.

Capable of working over both sides of the vessel, the gangway and tower will enable personnel from different deck levels to make their way to it without exposing them to the weather. The gangway is also capable of lifting cargo up to 1 tonne with motion compensation and will be able to handle trolleys and euro pallets of up to 300 kg.

SMST describes the combination of the access system and crane as “a modular set-up that maximises utilisation and performance whilst focusing on safety and efficient transfer of cargo and personnel”. In offshore mode, the crane will be capable of lifting 10 tonnes without compensation and 6 tonnes with compensation. At maximum draught, it will have a lifting height above water level of 26 m.

Thanks to the combined X-BOW and X-STERN configuration, it will have a particularly high level of operational flexibility when operating at an offshore windfarm or an offshore oil and gas installation. In particular, the X-STERN will allow for astern operations more than 70% of the time, significantly enhancing stationkeeping and manoeuvrability around turbines. The hullform will also experience substantially less slamming and hence lower levels of noise and vibrations and increased crew comfort.

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