Briggs Marine was appointed to install a replacement power cable between Mossbank and Yell. This cable forms part of SSEs distribution network around the Shetland Isles, an essential link in providing utilities to remote communities.
The 3.6km cable route crossed Yell Sound, an extremely challenging, high-energy area during winter months, where tidal currents were recorded up to 9 knots.
The installation utilised the main cable lay vessel Forth Guardsman, with Forth Fighter and Forth Constructor in attendance for support.
Briggs provided a complete suite of cable installation equipment, in conjunction with; vessels, personnel, survey, positioning packages and dive team.
Briggs consultancy team coordinated all marine consents on behalf of SSE prior to the installation; the area is classified with SAC and SSSI environmental designations so close consultation with SNH was required.
The installation was carried out over a period of neap tides in March 2010 to ensure the best possible slack water conditions to complete the installation. The operation was complex with strong tides running through channels on either side of Samphrey Island; timing of the installation and experience of working in the waters around Shetland was critical.
The seabed was cleared of redundant cables, which were recovered by Forth Constructor. All materials were disposed of and recycled through authorised channels.
The installation was carried out in a challenging high-energy area during the winter months, operating in strong tidal conditions, poor weather conditions and restricted daylight hours.