UK-based Offshore Marine Management (OMM) has completed a support services contract to Italy-based cables firm Prysmian with the installation of HVDC cable for the Sylwin 1 offshore wind farm in German waters.

Using the DP2 vessel Vos Sweet, OMM cleared the route proposed for laying the 160km high-voltage direct current export cable after identifying and retrieving out-of-service cables along the route for later safe disposal onshore.

The direct current export cable will connect the new wind parks to the onshore grid.

OMM said it carried out mattressing of the existing in-service underwater assets, including telecommunication and electricity cables and gas pipelines.

Furthermore, OMM’s team conducted a detailed survey of the sea bed, before identifying the correct position for each mattress and then releasing each into its location using a remotely operated underwater vehicle launched from the DP2 vessel.

A post-installation survey found that no interference with third-party assets had taken place.

OMM also used the Blue Capellato to conduct a pre-lay grapnel run (PLGR) to clear the seabed of debris and other unwanted materials to ensure that the route for the new Sylwin cable was clear and in good condition for installation.

OMM COO Eckhard Bruckschen said, “Despite challenging weather and some difficult seabed conditions, the out-of-service cables were successfully recovered and the route was proved clear in advance of the commencement of the cable lay.”