Who do you call when an internet cable at the bottom of the sea is severed?

Repair ships ready to sail within 24 hours once damage is reported

A scuba diver installs an articulated pipe round a cable. Photo: International Cable Protection Committee

A reliable internet connection is something we take for granted – until it gets disrupted.

That disturbance may be caused by damage to an undersea cable, as UAE residents found to their cost early last month when cables in the Red Sea were severed and internet speeds slowed down.

Many companies across the world are ready to respond when undersea infrastructure is damaged by, for example, fishing gear or a ship’s anchor, which together account for about three quarters of incidents involving telecoms cables.

Undersea landslides, in which shifting rock or sediment, and technical faults may also damage subsea cables, or they may be harmed deliberately, although this is rare.

There are dozens of repair vessels dotted across the globe, ready to be activated in the event of an incident, although it is not cheap work, with ships reportedly costing many tens of thousands of dollars each day they are at sea.

Among the companies that operate them is Orange Marine, which has six cable repair ships at off the coasts of places including Sicily, the South of France and South Africa.

“We have contracts with many cable operators in various areas and the contractual obligation will be to be able to sail within 24 hours,” chief executive Didier Dillard said. “Most of the time you need to load spare cables. It can take one hour, [or] one day.”

A ship may have to sail for up to 10 days to reach the site of the damage, which may be identified by sending a pulse down a cable, with the length of time that it takes to travel pinpointing the fault.

Most cable damage occurs in waters no deeper than several hundred metres. Down around 2,000 metres, an ROV (remotely operated vehicle) is often used to locate the cable, cut it and lift sections to the surface. Repairs take place on board, with the insertion of a replacement section along with connectors, before the cable is returned to the seabed. To reduce the likelihood of damage, the cable may be buried, perhaps down to a couple of metres.

Dealing with damaged power cables can take longer, especially if the original cable cannot be replaced. Photo: Orange Marine

Deep problems

Sometimes subsea telecom cables are thousands of metres below the surface, a depth at which fishing gear and anchors are not present. However, technical faults may necessitate repairs.

“To cut a cable at 6,000-metres depth, you have to use a cutting grapnel that you tow until it catches the cable,” Mr Dillard said, referring to a hooked, anchor-like structure.

“You pull the grapnel until it cuts the cable and use a different grapnel to pick it up, and insert the new cable and make some joints on it.”

Each ship has between 55 and 65 crew on board and they will typically carry out a single repair before returning to port, as the specific type of cable needed for the work has to be loaded on board in advance.

Vessels of this kind may have three crews in total: two on board and a third on shore leave.

Although companies such as Orange Marine and a Dubai-based firm called E-Marine, which also operates cable repair ships, are ready to sail quickly when an incident is reported, work may be delayed because a permit is needed in territorial waters, which are those under the jurisdiction of a particular state.

According to the International Cable Protection Committee, there are now about 1.7 million km of subsea cables in the world, around 70 per cent up on the 2014 figure.

Yet the organisation reports that the number of incidents each year involving cables has remained stable, at about 150 to 200.

Mr Dillard suggested the lack of an increase may be because cables are increasingly well protected, such as by being buried under the seabed.

Also, cable owners may monitor shipping activity and warn fishing vessels of hazards, a practice Mr Dillard said had contributed to “a significant decrease” in the number of faults in the North Sea, for example.

“They can identify fishing vessels approaching a cable and contact them by radio before they damage a cable,” he said.

While the severing of two cables in the Red Sea affected internet services in the UAE and other countries, including India and Pakistan, faults typically go unnoticed by the public because traffic is rerouted through other cables.

Mr Dillard said it was only in exceptional incidents, such as when several cables are damaged simultaneously, that the public notices.

Disrupting service

In early 2022, a volcanic eruption broke the fibre optic cable that connected the Pacific island of Tonga with the rest of the world, causing significant disruption. Repairs were slow because the nearest repair boat was almost 4,800km away, although a 2G signal was set up, allowing some internet access.

Tonga was unusually vulnerable because it was serviced by a single cable. By contrast, a large nation may be connected by dozens. Cable repair is highly specialised, technical work, so different ships will work on, for example, telecoms and power cables, respectively.

It can be more difficult to repair power cables, as these tend to be much thicker, typically weighing 30kg to 150kg per metre, compared to 10kg to 15kg per metre for telecoms cables.

“If you have a power cable and you take a section of one or two metres, that weighs over 100kg and that … [is] very stiff, nearly like a pipeline,” said Jack Wattel, director for subsea cables at N-Sea, a Dutch firm that repairs power cables.

“To handle such heavy, stiff cables, you need a lot more space, you need a lot more room to bend the cable, so by definition a power cable repair vessel always needs more deck space, needs bigger equipment, needs heavier equipment to deal with the minimum bending radius of the cable and with the weight of the cable.”

Also, telecoms cables tend to be more standard in specification than power cables, Mr Wattel said, another factor that often makes them easier to repair.

Dealing with damaged power cables can take longer, especially if the original cable cannot be replaced. Simply making a joint can take a week.

“The repair of a subsea power cable normally takes about two months, because you have to make those joints, you need good weather, and it’s a lot more physical activity to actually cut the cable, get them on board, prepare them for the new joint, then have to overboard that joint and protect it again, because you don’t want the next fisherman to come along and wreck it,” Mr Wattel said.

There can be significant consequences when subsea power cables are damaged: for example, offshore wind farms could lose their grid connection and cause a black out.

“In the Middle East you have a lot of cables connecting oil and gas facilities,” Mr Wattel said. “A lot of these cables are not even protected by burial or any other way of protection, so it’s very easy to damage them by external forces, like anchors of ships.

“The advantage is these are relatively small cables, they’re not buried, so you can repair them quite quickly. So if somebody’s in the neighbourhood with the right vessel and there’s spare cable available, and there’s spare accessories and joints available, you can probably repair that cable in two weeks to one month.”