Rock work rolling at Sheringham Shoal

The Jan Steen and the HAM 602 are undertaking procedures to protect the foundations and the J-tubes which house the cabling at the base of each of the 317MW windfarm’s 88 turbines.

The Jan Steen will be used first and will place a cushioning layer of small rocks around the foundations through a pipe fitted to its stern. The second vessel, the HAM 602, is a side dumper which will follow the Jan Steen to place a larger sized armour layer of rocks in an elliptical formation around each foundation.

Both vessels will load their rocks from two bulkers which will be anchored to the north of the wind farm on a rotational basis to ensure a constant supply of rocks. General manager for Scira Offshore Energy, Einar Strømsvåg said, “Protecting the foundations of the turbines will add to the longevity of the wind farm, and will reduce the cost of future maintenance. Rock installation can only take place at slack water, although surveys can be completed in slightly higher currents. To minimise the timescale for this operation, we hope to establish a work pattern so that rocks can be placed at four different locations while pre-surveying the next four and post surveying the previous four.”

Sheringham Shoal is owned equally by Statoil and Statkraft through the joint venture company Scira Offshore Energy Limited. Statoil is the project manager during construction, while Scira will be responsible for the long-term operations and maintenance of the wind farm.