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Marine Notice: Trenching and Boulder Clearance for Celtic Interconnector Project

13th April 2025
Works will be conducted by the trenching support vessel Aethra
Works will be conducted by the trenching support vessel Aethra Credit: Asso.subsea

The Department of Transport has been advised by Asso.subsea that they will be performing trenching and boulder clearance on behalf of Nexans for CIDAC as part of the Celtic Interconnector undersea cable project.

It is estimated this section of the campaign will last around 30 days and will take place between 5 May and 5 June, subject to operational and weather constraints.

The operations (boulder clearance and trenching operations) will be conducted within the cable corridor extending +/-200m each side of planned cable centreline and in between designated waypoints. Offshore mariners are advised to provide a wide berth and navigate with caution in the area.

Works will be conducted by the trenching support vessel Aethra (callsign SVDM6). During operations, the vessel will keep a listening watch on VHF Channel 16 and will actively transmit an AIS signal. A listening watch will also be maintained on VHF Channels as appropriate.

The trenching vessel shall broadcast daily, and at shorter intervals as may be required by passing traffic, the vessel position, operational information, and planned operations for the following 24 hours.

The project has requested that anybody having prior knowledge of potentially submerged or moored objects on the seabed within the operations area, which could form a hazard to the vessel/equipment, should contact Asso.subsea ahead of the planned works.

Contact details, as well as a map and coordinates of the work area, can be found in Marine Notice No 21 of 2025 attached below.

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Published in Undersea Cables
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Undersea Cables

Undersea cables are vital to Ireland's connectivity, facilitating high-speed internet, telecommunications, and energy transmission. These cables traverse the Irish Sea, connecting Ireland to the United Kingdom and continental Europe, and play a crucial role in global communications.

Submarine Communications Cables:
Ireland is strategically positioned along major transatlantic communication routes. Approximately 75% of transatlantic cables pass near Irish waters, underscoring the nation's significance in global data transmission.
These cables are typically as wide as a garden hose, with the filaments that carry light signals being extremely thin—roughly the diameter of a human hair. They are sheathed in layers of insulation and protection, with cables laid nearer to shore using extra layers of armoring for enhanced protection.

Energy Interconnectors:
In addition to communication cables, undersea interconnectors are being developed to enhance energy security and support the transition to renewable energy sources. The UK has approved the construction of five new subsea interconnector cables to boost the grid's flexibility amidst rising renewable energy. These projects will link the UK with wind farms in Belgium and the Netherlands, and connect England with Germany, Wales with Ireland, and Scotland with Northern Ireland. The cables, with a combined 6GW capacity, are expected to be operational by 2032, increasing the UK's total interconnector capacity to 18GW.

Security Concerns:
The strategic importance of these undersea cables has raised security concerns. Incidents in the Baltics have heightened awareness about the potential risks to subsea infrastructure. Ireland's historical neutrality and limited defense resources have led to calls for enhanced maritime security and defense investments, including modern surveillance technology and international cooperation. The government's response includes participation in EU security projects and collaboration with neighboring countries on maritime security.

In November 2024, a Russian spy ship, the Yantar, was escorted out of the Irish Sea by the Irish navy after it was found patrolling an area with critical submarine pipelines and cables. The vessel's presence heightened concerns due to its proximity to interconnector cables vital for internet services linking Ireland to the UK, operated by major tech companies such as Google and Microsoft.

Regulatory and Policy Framework:
The protection and maintenance of undersea cables fall under the jurisdiction of national governments, with private companies often responsible for their security. In Ireland, the Department of Communications, Climate Action and Environment oversees the regulation of telecommunications infrastructure, including undersea cables. The Irish Naval Service plays a role in monitoring and protecting maritime infrastructure, including undersea cables. Internationally, the United Nations Convention on the Law of the Sea (UNCLOS) provides a framework for the laying and maintenance of submarine cables, recognizing the "freedom of the seas" and the rights of coastal states.

Conclusion:
Undersea cables are indispensable to Ireland's connectivity and economic infrastructure. Given their strategic importance, ongoing efforts are necessary to ensure their protection and resilience against potential threats. This includes enhancing security measures, international cooperation, and adherence to regulatory frameworks to safeguard these critical assets.