Thanet on schedule

Weather permitting, the planned timescale should see the remainder of the foundations and transition pieces installed by the end of 2009. The installation of the actual towers, turbines and blade assemblies is due to commence soon after, with completion planned for the summer of 2010. Cable laying work is scheduled to start in October 2009 with completion of this phase expected early in 2010. At the time of writing, 70 foundation monopiles and 58 transition pieces had been installed.

Two main installation vessels are currently involved in the project. The jack-up Sea Jack, owned by A2Sea of Denmark, is installing the foundations which are manufactured at Kats in Holland. After an inland waterway journey on the barges Osprey Carrier and E3501 to Vlissingen, the foundations are transferred two at a time to Ramsgate by Osprey Shipping’s tug Osprey Fighter.

At Ramsgate they are loaded onto the Sea Jack, which is being supported by the tug Stevns Arctic owned by Nordane Shipping of Denmark and the Dutch Viegers & Son Shoalbuster 3612 tug Bever. Driemast BV’s tug Meander also provides assistance at Ramsgate.

Logistical support including crew changes and mammal observation is being provided by the South Boats built support vessel Offshore Performer, owned by Offshore Wind Power Marine Services, and the crewboat Waterfall. The turbine installation vessel MPI Resolution, operated by MPI Offshore Ltd, part of the Dutch Vroon Group, is installing the transition pieces, which, as with the foundations, are loaded out of Vlissingen. The MPI Resolution will also be used to install the turbines themselves, again loaded out in Vlissingen.

The next phase of the operation will involve the laying of the cable network with infield cables linking each turbine to the offshore sub-station and further export cables connecting the wind farm itself with the shore at Pegwell Bay, just south of Ramsgate. A substation has been constructed at the site of the former Richborough power station and associated underground cabling has now been laid to Pegwell Bay.

Aberdeen based Subocean Group will be responsible for installation of the infield and export cables to be buried around 2.5m below the seabed. Two basic methods will be adopted using a cable lay barge and a DP2 class cable vessel. While the actual vessels involved may be subject to change the Subocean vessels earmarked for this work includes the subsea support vessel Polar Prince, currently on a two year charter to Subocean, the cable barge Subocean Discoverer (formerly AMT Discoverer) and the cable lay barge UR101.

Supporting the barges will be the JP Knight tug Keverne, the Portugese owned tug Red Dolphin, the workboat Maggie M from GSS (Plant) Ltd and the Voe Jarl from Lerwick based Delta Marine. Three workboats built to the Lyme Boats 16m Vigilante Workboat design and owned by Great Yarmouth based Enviroserve, Sea Beaver, Sea Weasel and Sea Otter will provide logistical support. Further support will be provided by Blyth based North Sea Logistics, which will be operating three newbuild E Class support vessels Vestas Endurance, Vestas Endeavour and Vestas Enterprise.

A significant part of the offshore element will be the substation. It is anticipated that for this installation the Russian owned self propelled crane vessel Stanislav Yudin, operated by Dutch contractor Seaway Heavy Lifting, will be utilised.

A project of this scale naturally involves a large number of separate contractors physically carrying out the work. Managing the coordination that is essential to ensure everything is in the right place at the right time is something which was clearly evident during MJ’s visit.

Project director Ole Bigum Nielsen told MJ, ‘Vattenfall is proud to be on schedule to complete the world’s largest offshore wind farm before the end of next year. Since taking the project over in November last year, work has progressed swiftly. This is due to good management and commitment from all the companies involved. Special credit is due to all those working on the marine elements’.

Story and photos by Peter Barker