For multi MW turbines, such as the new turbines from GE, Siemens and MHI Vestas, the offshore wind industry needs larger installation vessels.
Rotor diameters of more than 150m, towers over 70m with a hub height over 100m require vessels with the dimensions to match the difference between the previously installed 3 to 4 MW turbines.
Fred. Olsen Windcarrier, owner of the Brave Tern and the Bold Tern has now completed the upgrade of the Brave Tern to match this class of installation work. By mid-summer the Bold Tern will have also undergone the same upgrade.
Since early November 2015 the vessel has been at the Rotterdam yard of Franklin Offshore Europe where the legs have been extended by 14m to 92.4, and the crane has been adapted to allow a 20m boom extension. The extension is able to be fitted any time in the future and the A frame has been already extended to give the crane greater performance with a 120m lifting height and a lifting radius of 35-40m.
The vessel will be able to carry 4 complete multi MW turbine sets consisting of towers, nacelles and blades for installation after this upgrade.
The Brave Tern will be sailing to Block Island Wind Farm this summer to install the GE Haliade 6 MW turbines on the first offshore wind farm in U.S. waters. Until then it will be employed on short O&M contracts in Europe.
Dick Hill, Offshore WIND Staff; Photos: Navingo/ Fred. Olsen Windcarrier