Netherlands-based subsea company wraps up nearshore cable repair in Irish Sea

Netherlands-headquartered subsea solutions provider N-Sea has completed a nearshore export cable repair in the Irish Sea after a fault in one of its client’s four subsea cables reduced transmission capacity between offshore and onshore substations.

According to N-Sea, the company was awarded a contract to provide a turnkey, fast-response repair solution in a nearshore location with water depths of 0 to 2 meters at the lowest astronomical tide (LAT).

N-Sea’s fault-finding and engineering efforts led to the installation of a spare cable section between the onshore transition joint bay (TJB) and an offshore location at KP1.0. Acting as the principal contractor and designer under the CDM, N-Sea handled the engineering, analysis, and preparatory work required for both onshore and offshore stages before initiating the repair.

The project involved pre-survey techniques, including a multi-beam echosounder hydrographic system (MBES), side-scan sonar (SSS), sub-bottom profiler (SBP), magnetometer, light detection and ranging (LIDAR), and onshore clean propulsion technologies (CPT), to secure a viable cable route. N-Sea then loaded and transported a spare cable from its storage facility in the Netherlands to the UK for mobilization.

For the offshore phase, N-Sea said it had deployed two jack-up barges equipped with cable-lay and jointing equipment, cranes, accommodation modules, and supporting tugs. An additional multi-cat vessel with a mooring spread was mobilized to carry out cable de-burial, fault finding, subsea cutting, and removal of the damaged cable, with the new cable buried after the repair.

Onshore operations included setting up a full site to facilitate cable landing, handling two cable crossings, and removing the old cable before burying the replacement and applying thermal grouting of the HDD, the company said. The TJB was also modified to house a new onshore joint.

Both onshore and offshore joints were installed to finalize the repair, with the TJB fully reinstated, allowing the client to re-energize the cable and resume green energy transportation.

N-Sea Subsea Cables’ Operations Manager, Dale McDonald said that the engineering and execution of this scope within a short timeframe demonstrates N-Sea’s capabilities in all aspects of nearshore installation and repair works.

The client commented: “This repair was, without doubt, the most complex cable repair intervention that we have carried out to date. N-Sea actively sought out solutions for the complexity that we faced and delivered the repair safely and successfully. This is the second repair we have completed using N-Sea and we are very grateful for the support and cooperation in delivering this repair.”

In July, N-Sea completed the acquisition of compatriot company Geo Plus, which continues to operate independently from its office in Groningen.

In August, the company’s recently launched dedicated subsea cable repair and installation vessel completed its first cable replacement project and is carrying out another one for the same client.