The boulders were relocated along the 85-km export cable corridor, at the offshore substation platform, around each foundation location and along the 150 km of array cable positions. They were relocated within Inch Cape’s consented boundaries between three and 150 m from their original location.

The boulder campaigns have been carried out to enable offshore construction activity including: cable installation and burial, foundation installation, and wind turbine construction by jack-up vessel, Wind Mover.

The number of boulders were relocated over several campaigns as part of the EPCI array cable contract Inch Cape awarded to TKF. The relocation teams were working 24/7 onboard marine contractor N-Sea’s multi-purpose vessels FS Aries, 4-Winds, and Pathfinder. The initial geophysical surveys were carried out from modern hybrid survey and support vessel Geo Ranger to map and identify anomalies on the seafloor.

The boulders were left by glaciers retreating from the Firth of Forth during the last glacial period which ended around 11 500 years ago and their diameters ranged in size from 30 cm – 2.5 m.

They were moved using specialised marine equipment including remotely-operated vehicles (ROV) and auxiliary remotely operated vehicles (AUXROV) fitted with a boulder grab which picks up and moves the boulder to a location outside the construction area. The multi-purpose AUXROV system used by N-Sea is designed for heavy-duty subsea tasks and can be equipped with various tools including boulder grabs, excavators and cutting tools.

The ROVs and AUXROVs were operated and monitored from a control room onboard each vessel known as the ROV container.

The boulder relocation work was authorised to be carried out under marine licenses granted by the Marine Directorate and co-ordinates of all the boulder locations have been provided to the Scottish Fishermen’s Federation for sharing with the local fishing industry.

While there may be some final boulders to be relocated due to engineering requirements during installation, Inch Cape’s planned boulder relocation campaigns are now complete.

Some bonus marine life images were captured by the camera on the auxiliary remotely-operated vehicle as the lights on the equipment attract sea creatures, with the sizeable lobster, passing seal, and hermit crab in its shell home.

For more news and technical articles from the global renewable industry, read the latest issue of Energy Global magazine.

Energy Global’s Spring 2026 issue

The first issue of 2026 is here! The Spring issue starts with a report about price cannibalisation, and the effects on the renewable energy industry before moving on to articles on topics including electrical infrastructure, solar optimisation, and site surveys and mapping, with contributors from industry leaders such as CESI SpA, APEM Group, North Star, and more – don’t miss out!

Read the article online at: https://www.energyglobal.com/wind/06052026/inch-cape-completes-offshore-boulder-relocation-programme/