Ampelmann and C-Job Naval Architects have joined forces to develop a one-of-a-kind offshore wind feeder vessel concept with motion compensation technology. The vessel is specifically suited for the rigorous demands of operating off the east coast of the United States of America.

The concept design combines the knowledge of Ampelmann, the Dutch offshore access provider, and independent ship design company C-Job Naval Architects. Together they have created a viable solution in response to the need to support the construction and logistics of offshore wind farms in the United States under the Jones Act.

‘The United States is ambitious in its plans to grow the installed offshore wind power. The only viable way to realise this goal while complying with the Jones Act is utilising offshore wind feeder vessels,’ says Todd Allen, VP business development at C-Job Naval Architects. ‘Together with our strategic partner Ampelmann, the experts in motion compensation, we have created an innovative ship design ready to support construction of US wind farms today and into the future.’

Offshore wind feeder vessel design

The state-of-the-art offshore wind feeder vessel has an L-shaped superstructure. This enables the transport of all wind turbine components, including the blades, while keeping the ship itself relatively compact minimising construction and operational costs. To maximise workability and allow for safe lifting of the components, the feeder vessel features a specially designed motion compensation system by Ampelmann.

The system uses Ampelmann’s core technology to stabilise the components of the wind turbine generator (WTG) in six degrees of freedom and is designed for safe lifting operations in sea states up to 2.5 metres significant wave height. The compensator is positioned close to the vessel’s centre where it can compensate all vessel motions and allows for continued operations – even in adverse weather conditions – throughout the year.

Gus DeOliveira, Ampelmann’s Business Development Area Manager for the Americas, explains: ‘We see a lot of potential for the offshore wind market in the US and believe that we can add some unique value based on our decades long experience in the offshore wind market. Our partnership with C-Job is crucial if we are to design and deliver just the right solution for this growing market.’

Offshore wind feeder specifications:

  • Length overall (approx): 103.5 m
  • Breadth (moulded): 23.8 m
  • Depth maindeck: 9.2 m
  • Draught (design): 5.5 m
  • Sailing speed: 13 kn
  • Complement: 20 crew + 12 passengers
  • Workability of the Ampelmann system: up to 2.5 m Hs
  • Additional features: DP2

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Grip and glide system

The wind turbine components are arranged on the ship with a quick connect grip and glide system. Cargo pallets are placed on deck quickly thanks to the quick connect system. Once the feeder vessel is at its destination, the system slides the components into place to connect to the motion compensator. The Ampelmann system then compensates all vessel motions, so the crane operator can lift turbine components in a similar fashion to an onshore lift.

Separate vessels for transport and installation

The motion compensated wind feeder vessel is designed to provide maximum efficiency and workability during the construction of an offshore wind park. The conventional way of working is that the installation vessel would transport the components and then do the installation of the turbines. However, this is an inefficient use of the wind turbine installation vessel (WTIV) and in the case of foreign vessels not allowed by the Jones Act.

With this feeder concept – which is envisioned to be a series – the turbine components are brought to the installation site by the feeder vessel. With two or more vessels per project, this allows the WTIV to focus on the installation of the turbines and ensures operations can continue at all times.

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