PLGR, RC and PLIB activities in North Sea

Service PLGR, RC, Touch Down Monitoring (TDM) & PLIB activities
Location North Sea
Water depth 5-1160 m
Project duration 2 months (2020)
Industry Submarine telecommunication cable
scope of work

In October 2020, ACSM has been contracted by a leading submarine communications Company to provide ROV support activities during the laying of about 30km submarine cable, outside the French Atlantic coast.

The scope of work included the provision of vessel, ROV and personnel for:

  • Pre-Lay Grapnel Run (PLGR)
  • Route Clearance operations
  • Touch Down Monitoring
  • Post-Lay Inspection and Burial (PLIB) works


To support the cable installation activities, ACSM deployed the owned offshore support vessel NAUTILUS.
The NAUTILUS is designed to the highest standards required for the offshore industry and ideally suited for a broad range of pre-engineering activities, construction support and IMR operations.

At 75 metres long, with a cruising speed of 10 knots and accommodation for 44 personnel, ACSM Nautilus is a robust, practical and efficient vessel for all inspection, survey and installation support requirements.

The vessel also has integrated ROV control, online inspection, survey and offline processing/review offices and client offices.

Partenza nautilus


The Cable Maintenance ROV (CMROV) is a free swimming or tracked hydraulic ROV with 300kW/400HP providing an efficient and cost-effective solution for maintaining and installing regional and intercontinental submarine cable systems. This type of ROV has an extensive track record for operating globally in extreme environmental conditions and a variety of seabed soils.


Route Clearance

ACSM provided Route Clearance operations which consisted in removing from the route, any end-of-life cables identified during the preliminary survey.

Pre-Lay Grapnel Run
The Pre-Lay Grapnel Run was carried out by dredging a grapnel to clear any obstacle that could obstruct the plough during the installation.
ACSM work class CMROV was used to perform touchdown monitoring during cable installation and to carry out the Post-Lay Inspection and Burial (PLIB) when cable is laid and buried.
Client satisfaction:
The project has been successfully completed within the schedule also thanks to deployment of the NAUTILUS as support vessel, carrying the Post-lay inspections while the main Lay-vessel, operated by the Client, was completing the cable installation.

Turning complex subsea challenges into safe and efficient operations