ANTONY SAVVAS CABLE DAMAGE
The operator can notify the ship to change course or retract its anchor before it’s too late. This technology is still in its early stages though, and cannot be deployed over the entire length of a cable system. But it can be deployed over the first 50 km or so, which is important because most damage occurs in shallow waters closer to shore, as opposed to deep waters where there are reduced threats. On cable installation, James Ovel, chief operating officer of network infrastructure provider Zayo Europe, says, “Installing subsea cables as deep as possible is a key way to reduce outages. Our Zeus cable, which connects the UK to Europe, is buried more than two metres beneath the sea bed. This burial depth is vitally important as the sand on the seabed changes in depth, typically by up to two metres in constant tides, known as ‘sand waves’. Maintaining a minimum two-metre burial depth at all times protects the cable from exposure to fishing trawlers, anchor strikes, and cable degradation caused by constant movement.” INTENTIONAL DAMAGE? So, is it possible to detect intentional damages to subsea cables? VIAVI is a player in the subsea sensing market, which also includes the likes of ASN (recently sold by Nokia to the French government), FiberSense, and Sipartech. A VIAVI spokesperson told us that detecting deliberate damage can prove tricky, “Larger ships are legally required to have and operate automatic identification systems, which are basically location and identity beacons. This makes ships trackable, but as we’ve seen in recent news these systems can be faulty or turned off.” One way to determine deliberate outages versus other causes is with on-going monitoring of cable health. “By monitoring cable strain, you can identify gradual deterioration or fatigue over time, due to things like tidal/ current movement, exposure of buried cable, or rock snagging, so if an outage is related to something flagged due to
cable deterioration it’s less likely to be a deliberate outage,” says VIAVI. Philip Murphy, networks principal, marine operations, Telstra International Networks, concurs that it can be as murky as the water the incidents often happen in, when trying to detect sabotage. “A review of the vessel track using AIS or fibre sensing can suggest deliberate outage if the threat vessel zig-zags across a cable route. However, in recent decades, outages initially suspected as sabotage have usually been traced to ships dragging an anchor, if conspicuous tracking is excluded. Incidents can arise from a storm or commercial fishing activity, making it challenging to differentiate between deliberate and inadvertent acts that take place prior to an outage.” Zayo’s Ovel adds, “While it can be difficult to distinguish between deliberate and accidental subsea cable damage, you can weigh up different factors such as physical evidence, surveillance - including advanced sensor technology - and situational context to more easily determine how the damage was caused, and mitigate risks for the future. We ensure our subsea fibre infrastructure is constantly monitored, looking for any signs of interference or irregular patterns.” SENSING DEMAND Distributed fibre sensing, specifically Distributed Acoustic Sensing (DAS), provides proximity warnings, allowing ships to be notified and take aversive action if they are potentially threatening cables. Brian Lavallée, senior director of network solutions at Ciena, says the demand for different sensing solutions is certainly widening. “There are different methods such as fibre-based sensing, such as State of Polarisation (SOP), Phase, and DAS, and point-based sensing like science monitoring and reliable telecommunications (SMART), which all have multiple pros and cons, like cost, range, sensitivity, reliability, primary function, and so on.” While Lavallée confirms that overall
demand for sensing is up, different factors can determine deployments, or not. VIAVI says, “Fibre sensing systems require an optical fibre to be attached, bonded or embedded in a cable, so for already deployed cables this doesn’t usually happen due to the operational challenges and costs of retrofitting. Much better to include sensing at the planning stage for new deployments.” Telstra’s Murphy agrees, “Sensing systems are more likely to be deployed on new cables, rather than existing ones. Deployment requires a risk assessment of the cable route, as it may not be cost-effective for a deepwater cable where the risk is assessed to be low.” SECURITY BY DESIGN? Dani Simis, CTO of NED, the Israel- based data centre owner and operator, says, “Sensors should be requested in the planning phase and before installation. The costs of retrofitting an existing cable are much higher, as mobilising new ships with the equipment and personnel to install an underwater cable is very expensive. The operation is also very risky for buried, powered, and active cables. Installing the sensors with the main cable-laying ship is much easier and has fewer risks.” So, despite sensing clearly offering some extra cable protection, are new cable owners considering it at the design stage? Pioneer’s Tully says the initial response is pretty negative. “As a rule, the answer is no. By and large, cable owners are still not planning these technologies as part of their initial design or ‘must haves’. We are hired to design systems and help with procurement and construction, but we rarely see owners request these technologies even if we recommend them. However, there is a growing interest overall, and I’m optimistic that we will see growing adoption of sensing in the future.” While subsea cable threats continue to make the news, perhaps the cost of greater protection is a major block on preventing outages.
Tony O’Sullivan CEO, RETN
Gavin Tully Managing Partner, Pioneer Consulting
James Ovel COO, Zayo Europe
Philip Murphy Networks Principal, Marine Operations, Telstra International Networks
Brian Lavallée Senior Director, Network Solutions, Ciena
Dani Simis CTO of NED
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ISSUE 40 | Q1 2025
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