The communications revolution and seabed hazards

If truth is the first casualty of war, the second is probably underwater communication cables which the history of the last century informs us are severed simultaneously with the opening of hostilities. There are many more of these undersea conduits today, which might account for the current angst being expressed about their vulnerability to hostile powers. 

The UK Policy Exchange has just published a report on the subject, suggesting the level of harm that could be done with a few snips of the shears on the sea floor to international communications, which contrary to popular opinion, overwhelmingly rely on fibre optic cabling rather than satellites for their heavy lifting of data. 

The report hints at the activities of Russian submarines lurking around the routes of the undersea communication cables and stresses the vulnerabilities of the remote locations where these vital arteries come ashore. It is suggested that insufficient attention has been given to the defence of these cables, although quite what can be done to defend them against submersibles with sharp shears remains unspecified. 

While this new menace might be occupying the thoughts of military strategists, mariners probably would say that such has been the level of obstruction on the seabeds there are far fewer places where they might safely drop an anchor. Submarine cables are carefully marked on the charts and once they were sufficiently rare to be regarded as a remote risk of fouling one’s anchor. Today in many places where there is heavy surface traffic, a positive cat’s cradle of cabling and pipelines lurk on or just below the seabed, a real cause of concern to shipping. 

Cable ships were once rare beasts, today there are dozens of them, connecting up all the wind turbines and joining up to the nearest shore side electricity grid. Oil and gas pipelines litter the seabed along with the growing amount of associated sub-sea equipment which lives permanently below. This is in addition to the precious communication links of fibre-optic cabling that carries our commerce (and probably this very article from my word processor),  around the world.

These cables are indeed well-marked, they are supposed to be buried in trenches by ploughs when they are in water shallow enough to see them harmed by a stray trawl warp or loose anchor, but they are still vulnerable to the effect of tides and currents and our shifting underwater sands which sometimes strip away the overburden of rock and leave the cable or pipeline exposed. But there are just so many of them. Ships will often anchor in extremis, in bad weather or because they have suffered an engine breakdown. It is not unknown for them to drag their anchor and when it is weighed, to damage the cable or pipeline.

A few years ago I was aboard a cable repair ship that had returned from a month’s intensive work after a ship had run through the Dover Strait and Southern North Sea with an anchor dragging along the sea bottom after it had paid out, all unknown to those aboard, in very heavy weather. Several cables were damaged in that single incident. Lawyers like to refer to the celebrated case of the Marion, which in 1977 dropped an anchor off the River Tees on top of a vital gas pipeline and, because of her ill-corrected charts, was found liable for a colossal sum, with owners unable to limit their liability.  

So as this huge network of underwater obstructions spreads around our “sustainable” sources of power generation and even more communication cables are laid, the risk of damage increases. Maybe the authorities should be worrying about hostile powers and their grapnels and shears. There is probably a better case for being rather more sensible about where cables are laid, bearing in mind the regular passage of merchant ships and the activities of fishermen, who also share the seas. 

Posted 12 December 2017

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Michael Grey

Columnist and correspondent

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