Ampelmann and C-Job Naval Architects have joined forces to develop an offshore wind feeder vessel concept with motion compensation technology, specifically suited for the demands of operating off the USA’s East Coast.

Ampelmann and C-Job said the vessel would be able to support the construction of offshore wind farms in the USA under the Jones Act rules.

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

With Ampelmann and C-Job’s concept, which is envisioned to be a series, the turbine components are brought to the installation site by the feeder vessel. Two or more vessels could be deployed on the project, allowing the WTIV to focus on the installation of the turbines, ensuring operations can continue at all times.

The 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, said the companies. To maximise workability and allow for safe lifting of the components, the feeder vessel features a motion compensation system designed by Ampelmann.

The system uses Ampelmann’s core technology to stabilise the components of the wind turbine generator and is designed for safe lifting operations in sea states up to 2.5 m 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, said Ampelmann and C-Job.

The wind turbine components are arranged on the ship with a connect grip and glide system, which enables cargo pallets to be placed on deck quickly. 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.

Todd Allen, vice president business development at C-Job, added: “The USA 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. 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.”