Rockabill: Connecting Dublin and Southport
A 224 km resilient subsea fibre system delivering reliable Ireland - UK connectivity across one of the busiest and dynamic marine corridors in Europe.
Project Overview
Rockabill is a 224 km unrepeated subsea fibre optic cable system crossing the Irish Sea between Portrane and Southport, delivering a resilient and diverse route between Ireland and the United Kingdom. The system entered service in November 2019 and has since proven to be a secure and reliable system in the Irish Sea.
The Rockabilll project represented a major infrastructure deployment, delivering over 1,000 kilometres of high fibre count cable, including the 224 km subsea section. 340 new chambers, 239 new fibre joints, 2 new cable landing stations, and 4 new ILA/PoP sites – all completed in just 9 months.
Designed to reduce reliance on older legacy systems, Rockabill provides diverse routing that forms part of euNetworks’ Super Highway network. This creates unique connectivity options between Dublin, Manchester, and London, with flexibility to bypass regional congestion. The infrastructure also enables Dublin-to-Amsterdam connectivity via a Central London bypass, avoiding metropolitan bottlenecks.
Commissioned by euNetworks to deliver full lifecycle engineering and project management services for Rockabill, covering planning, design, permitting, procurement and installation supervision. MDM maintains ongoing Operations & Maintenance responsibilities for the Rockabill subsea system, ensuring continued operational excellence.
Rockabill's Challenge:
The Irish Sea presents a demanding environment for subsea cable deployment. Strong tidal currents, variable seabed conditions, dense marine activity and intensive fishing have historically contributed to damage and service interruptions on older legacy systems. Securing approvals for new infrastructure in this region required navigating complex regulatory processes across Irish and UK jurisdictions, spatial constraints and competing marine interests.
The Rockabill project also faced operational challenges associated with installation scheduling. Additional challenges were vessel availability and coordination across multiple project stakeholders. The project objective was to deliver a well-buried system that could withstand long-term environmental and operational pressures, while moving efficiently through permitting and installation.
Key Features of the Rockabill System
Europe’s digital sovereignty depends on infrastructure it can control and trust. Delivering this vision required a bold, technically ambitious project: a secure subsea cable system spanning multiple jurisdictions, aligned with EU goals for resilience.
224 km Route
Engineered to operate without subsea repeaters, simplifying system architecture while improving latency, reliability and long-term maintenance efficiency.
Secure burial integrity
Ploughed burial along the main lay route, combined with targeted protection at nearshore and landfall areas, delivers robust physical security across the system.
Diverse Ireland-UK Pathway
Part of euNetworks‘ Super Highway connecting Dublin, Manchester, London, and Amsterdam. Provides diverse routing options and London bypass capability for reduced latency and congestion avoidance.
Ongoing Operational Excellence
MDM has delivered ongoing Operations and Maintenance (O&M) services since service commencement in November 2019, ensuring continued system reliability. Minimal reported service interruptions from cable infrastructure failures.
Our Solution:
MDM delivered full lifecycle engineering and project management services for the development of the Rockabill Cable System. MDM led the design, permitting, and procurement phases, and supervised installation focusing on long-term reliability and operational performance throughout the lifecycle of the system.
The 224 km subsea cable operates without repeaters, eliminating mid-sea electronics and simplifying maintenance while improving latency. MDM engineered the route and coordinated ploughing operations to bury the cable wherever seabed conditions allowed, with targeted protection measures at shore ends and nearshore sections.
Rockabill reflects MDM’s end-to-end subsea engineering capability and the specialist services we provide across the full subsea cable lifecycle.
Unrepeated 224 km System
The cable operates without subsea repeaters, eliminating underwater electronics and reducing failure points. This design improves latency, delivers lower lifecycle costs, and enables future technology upgrades at shore-based stations only – no underwater intervention required.
Ploughed Cable Protection
MDM coordinated ploughing operations along the main lay route, burying the cable wherever seabed conditions permitted, and implementing targeted protection measures for nearshore and landfall areas; delivering robust physical security across the system.
Diverse Network Architecture
Provides an alternative, diverse route across the Irish Sea, reducing dependency on older legacy systems. As part of euNetworks‘ Super Highway network, Rockabill enables flexible routing between Dublin, Manchester, and London, including bypass options to avoid regional congestion.
Quantum-Grade Infrastructure
In October 2023, researchers from the University of York, in collaboration with the Quantum Communications Hub and euNetworks successfully demonstrated that quantum communication signals could be transmitted over a 224 km subsea optical fibre link between the UK and Ireland using the commercial Rockabill subsea cable. This was the first quantum link between Ireland and the UK, and the longest subsea quantum link established at the time. The cable’s ultra-low loss characteristics (0.17 dB/km average attenuation) made it ideal for this groundbreaking security research.
The MDM Results
Rockabill has strengthened Ireland–UK’s digital connectivity since November 2019, delivering measurable operational and strategic value:
Network Diversification:
Provides alternative routing across the Irish Sea, reducing dependency on older legacy systems and creating resilient connectivity options for critical data traffic between Ireland and the UK.
Advanced Technology Platform:
In 2023, the cable's exceptional performance enabled University of York researchers to successfully demonstrate quantum communications, establishing the first quantum link between Ireland and the UK. This achievement validates Rockabill's suitability for next-generation secure communications applications in financial services, government, and pharmaceutical sectors.
Network Integration Value:
As part of euNetworks' Super Highway network, Rockabill enables data centre-to-data centre connectivity across Dublin, Manchester, London, and Amsterdam with flexible routing options. The infrastructure supports bypass configurations to avoid London congestion, delivering lower latency for time-sensitive applications.
Operational Continuity:
MDM's ongoing Operations & Maintenance role ensures continued system optimisation and rapid response capability, maintaining the operational excellence established during the project delivery phase.
Testimonial
Let’s Build Europe’s Digital Future... Together
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