When Marine Current Turbines were looking for a contractor to drill the foundation sockets for the installation of their 2nd generation turbine ‘Seagen’ in Strangford Lough, the obvious choice was to approach Fugro Seacore who had successfully drilled the foundation for the first turbine off the north coast of Devon.
The foundation structure at the turbine was a quadrapod design base with four 1016 mm diameter piles, grouted into 1150 mm sockets, to enable fixing to the seabed.
To drill the sockets the complete turbine structure was positioned and levelled on location and a work platform bolted to the top. Conductor tubes were then set through gates in the platform into guides in the quadrapod base. FSCL positioned its B5 drill on top of these and drilled a 7.4 m socket into hard mudstone.
Difficult working conditions
Site conditions were harsh; the seabed being extremely uneven with a covering of cobbles and boulders.
Currents reached around 4 m/s on Spring tides which made operations such as installing conductors and crew transfers hazardous, however despite these conditions drilling was successful and finished ahead of schedule.