Irish Sea Gas Interconnector: Diving interventions, Isle of Man, September-October 2021

[Please note – this work has now been completed.  The Notice to Mariners has been withdrawn.  This information has been left on the website as part of the archive of published information for the project.]

Mariners are advised that diving interventions are due to take place in the vicinity of the Isle of Man “Subsea Tee” part of the high pressure gas interconnector pipelines running between Scotland, Ireland and the Isle of Man starting on the 25th September 2021.  A notice to mariners about these operations can be downloaded here and is summarised below.

Location & Duration of works

Diving operations on the existing gas pipelines are due to be conducted at the location below:-

  • Isle of Man Subsea Tee: 054° 20′ 30.83″N 004° 44′ 29.01″W (alternatively 054° 20.514’N 004°44.484’W)

The survey vessel Noordhoek Pathfinder will be carrying out these works.  A map of the pipeline route and the precise locations of the survey extent are provided in the Notice to Mariners which can be downloaded here.

The survey work is due to start on the 25th September 2021 at this location.  The survey is expected to take approximately 2 weeks.  During the survey the vessel shall be working on a 24 hour basis.

All dates are subject to sea and weather conditions.  Updates on the schedule will be provided as the survey progresses.

Vessel details

Information about the location of the vessel carrying out this work can be found at the Marine Traffic website using the link below:-

The survey vessel will be displaying the relevant day shapes and night lights as specified by the International Regulations for the Prevention of Collisions at Sea (“IRPCS”).  The vessel will be monitoring VHF Channels 16 and 12 and have a pro-active attitude monitoring the surroundings.

Due to diver operations, other vessels are asked to observe a 1,000m stand-off at all times.  The vessel involved in this work may be restricted in its ability to manoeuvre.

Further details about the survey vessel are given in the Notice to Mariners which can be downloaded here.

Additional information

The two Irish Sea Gas Interconnectors (“IC1” and “IC2”)are operated by Gas Networks Ireland (“GNI”).  A map of the GNI gas pipeline network is available here.  The two Irish Sea Interconnectors and the Isle of Man Spur were installed between 1992 and 2003.

GNI have produced a High Pressure Subsea Gas Pipeline Awareness leaflet (available here).  This leaflet shows the route of the pipelines, describes their structure and provides advice on safe operations in the vicinity of the pipelines.

Notices to Mariners

The Notices to Mariners that have been issued for the survey of the GNI Pipelines are listed below:-

  1. Diving interventions: September-October 2021 – this is the notice described above.  It provides information on the diving work that is due to take place in IOM waters between September and October 2021.  The notice can be downloaded here.
  2. Diving interventions: August-September 2021 – this notice was issued on 24th August 2021.  It related to the survey work on the IOM subsea tee which was subsequently postponed, and this notice has been withdrawn.
  3. Offshore surveys: July-August 2021 – this notice was issued on 9th July 2021.  The offshore surveys have now been completed, and this notice has been withdrawn.
  4. Shallow water surveys: July-August 2021 – this notice was issued on 29th June 2021.  These shallow water surveys have now been completed, and this notice has been withdrawn.


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