ABERDEEN, UK — Rotech Subsea has completed a cable cut and recovery operation at an offshore wind farm in Denmark using its RSG-C grab and cut tool.
The subsea jet trenching and excavation company was tasked with cutting and recovering a 165-mm diameter subsea cable in two locations at water depths of 16 m to 25m. Deployed by vessel crane, the RSG-C tool was controlled using a single deck winch routed through a fairlead at the aft of the vessel.
Guided by the vessel’s DP positioning system, a USBL transponder on the tool—along with a survey navigation screen set up in the Rotech control cabin—gave the Rotech crew real-time visibility of the tool’s location throughout the operation. A tool-mounted sonar imager allowed the tool to locate the cable. Once secured by the grab function of the tool, and inspected using an onboard camera and subsea lights, it was cut and recovered. Operations were assisted by a client-owned ROV, which provided a live video feed of the operations.
Speaking about the pipeline burial operation, Rotech subsea director of subsea, Stephen Cochrane, said, "Both cuts to the cable were completed in under 10 minutes, and the efficiency of the operation, and in particular the combination of cutting and recovery in a single tool, saved the client a significant amount of time over other proposed methods to complete the scope."