Saturday, 08 May 2021

Industry experts debate whether unrepeatered systems really are the simplest subsea solution

Anders Ljung, Business Manager, Hexatronic
Friday 04 September 20

Last Thursday Hexatronic hosted an interactive panel session entitled “The Simplicity of Unrepeatered Solutions – continuing your terrestrial network along the seabed?” Host Anders Ljung was joined by a prestigious line up of industry experts including Mattias Fridström of Telia Carrier, Hans-Martin Norstrøm of Nexans, Tom McMahon of Deep Sea Fibre Networks Ltd., Thomas Eklund of Baltic Offshore, Tobias Borg of Hexatronic and Ashutosh Bhargava of Prysmian Group. The session first came about due to concerns that the unrepeatered market was not well represented within the subsea arena; there is limited data available with regards to existing and planned systems and very little discussion at conferences about unrepeatered technology and supply. Hexatronic planned the panel to highlight their importance in global connectivity and the participating speakers had a wealth of experience ranging from procuring and deploying unrepeatered networks…

Last Thursday Hexatronic hosted an interactive panel session entitled “The Simplicity of Unrepeatered Solutions – continuing your terrestrial network along the seabed?” Host Anders Ljung was joined by a prestigious line up of industry experts including Mattias Fridström of Telia Carrier, Hans-Martin Norstrøm of Nexans, Tom McMahon of Deep Sea Fibre Networks Ltd., Thomas Eklund of Baltic Offshore, Tobias Borg of Hexatronic and Ashutosh Bhargava of Prysmian Group.

The session first came about due to concerns that the unrepeatered market was not well represented within the subsea arena; there is limited data available with regards to existing and planned systems and very little discussion at conferences about unrepeatered technology and supply. Hexatronic planned the panel to highlight their importance in global connectivity and the participating speakers had a wealth of experience ranging from procuring and deploying unrepeatered networks, to designing, manufacturing and installing the submarine cables themselves. As we know, unrepeatered systems have many applications, from short point-to-point links between countries & islands, to providing telecoms connectivity to oil platforms, off-shore wind farms, etc. As outriders or as an integral part of power cable systems, to harbour, river and lake crossings. And of particular importance at the moment is their ability to facilitate local connectivity to trans-oceanic cable systems.

The discussion started with a question about how unrepeatered systems fit into Carrier’s networks, and why they are often selected instead of terrestrial routes. Mattias highlighted the fact that unrepeatered cable systems are so much easier to upgrade from an optical perspective than repeatered systems, noting that only the fibre characteristics have to be considered. Upgrades are frequent, networks are complex, and hence simplicity is key. The panellists agreed that one of the benefits of unrepeatered cable design is that if systems are installed correctly and not subject to aggression or mechanical issues on the seabed, they remain operational and upgradable for well beyond their design life, with Matias advising that Telia are still putting new terminal equipment onto systems installed in 1995.

It was noted that in many parts of Europe, such as the Nordics, neighbouring countries are close enough to enable unrepeatered links to be used, and in some places Rights of Way for rivers were simpler to obtain than on land. This led onto a discussion about permitting, often considered the most complex and timely part of any subsea project. Tom pointed out that unrepeatered systems face the same challenges as repeatered ones in terms of obtaining permits in principle and seabed concessions. Of particular concern is that diversity requirements are often leading to landings in sub-optimal landfalls, and that seabed congestion and environmentally protected areas make routing more and more complex. This led to the conclusion that when installing new unrepeatered systems high fibre count solutions should be considered where possible to future proof against increased planning constraints.  Cable crossings were discussed, in particular the added complexity and cost of crossings in the North Sea. Thomas highlighted the regional differences here advising that in the Baltics there are many crossings along the coastline which are installed without issue. Tom pointed out that insurance requirements for crossing other party’s cables in the North Sea, Irish Sea and the Channel were becoming complex, in particular for HVDC crossings.

The discussion moved on to fibre quality and performance, and it was noted that high spec low attenuation fibres can extend the distance over which unrepeatered links can be operational with Ashutosh citing 16 x 100G capability of systems around 450km. Obviously ultra low loss fibres are more expensive and there is always a CAPEX trade-off between using high spec fibre on long unrepeatered systems and switching to a repeatered alternative. From a business case perspective Matias pointed out that the Carrier’s preference is to sell capacity instead of dark fibre (which allows the purchaser to upgrade at will). The ability to mix fibre types within the same unrepeatered cable was also noted and the opportunity this affords to sell different customers difference products.

From a technology standpoint the panellists discussed fibre count with Hans-Martin pointing out that the highest fibre count system Nexans had provided was a 2016 fibre cable, installed last year in a highly populated area. All the panel noted the difficulty in jointing high fibre count systems and agreed that the industry staples was still 96 fibres. As fibre counts jump up from 96 to 144 to 192 cables need to be UQJ qualified and the strict SLA’s for maintenance durations need to be considered. Ashutosh noted that NSW have had a lot of interest in 144 and 192 cables, which rely on ribbon technology for jointing.   The regional differences came to the fore again with Thomas advising that in the Baltic Sea the splice time does not make that much of a difference to the overall maintenance window as the weather is good – as we know this would not be the case in the North sea in the middle of winter.  The weight of the cable was discussed and also multi-vault versus single-vault solutions. Tom noted that early life failures of a cable system were hugely detrimental to the reputation of the route and noted that 2-3m burial was being requested in some regions alongside significant up-armouring. 

Anders then sought the panellists input on whether disaggregated supply was better suited for unrepeatered systems, and whilst it was noted that there are several advantages of disaggregation (the ability to buy at source and select the best solution for each element) the complexity of permitting, installation and aligning all the different supply-chain interfaces meant that in many cases turnkey supply was still preferential.  Moving onto regional demand Tobias noted that Hexatronic see growth in demand for unrepeatered systems in Europe and Asia, with Hans-Martin and Ashutosh agreeing. Feeder systems to new transoceanic repeatered links are playing a large part of current demand.  

Following a lively discussion several more questions were taken from the audience and Anders concluded that despite the title of the session, “The Simplicity of Unrepeatered Solutions,” all cable systems were indeed very complex and needed careful consideration and planning. Watch the session in full here.

 

 

 

 

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