Relying on GPS could leave you lost at sea

A study has revealed that a growing overdependence on satellite navigation could have catastrophic effects on boaters

Global Positioning System (GPS) gadgets have become such a big part of our lives, both on and off shore, that we are becoming dangerously dependent on the technology, according to a report from the Royal Academy of Engineering.

The GPS uses signals from satellites to provide precise timing and location details to everything from marine chartplotters to mobile phones but those signals are vulnerable to disruption with potentially devastating results.

Since the signals received by GPS systems are very weak – the equivalent to receiving the light from a bright bulb at a distance of 20,000km – they are open to interference or corruption, either from phenomena such as sun spot activity or malfunctioning TV aerials, to purposeful disruption using jamming broadcasts. Although jammers can be bought legally for as little as £20 online, it is illegal to use them in the UK.

Dr Martyn Thomas, who chaired the group behind the report, said, “We’re not saying that the sky is about to fall in; we’re not saying there’s a calamity around the corner.

“What we’re saying is that there is a growing interdependence between systems that people think are backing each other up. And it might well be that if a number of these systems fail simultaneously, it will cause commercial damage or just conceivably loss of life. This is wholly avoidable.”

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The report investigated the effects of commercially available GPS jamming systems on marine navigation by sailing the Northern Lighthouse Board vessels NLV Pole Star through a patch of sea blanketed by the jamming signal.

This caused the Pole Star’s GPS receivers, automatic identification system transponder, dynamic positioning system and gyro calibration mechanism to fail. Each of these systems was in some way controlled by or dependent on GPS.

“What was interesting about the Pole Star, which took place off Flamborough Head, was the range of results that we got,” said Richard Ploszek, the Royal Academy of Engineering’s senior policy manager responsible for compiling the report.

“Some of the readings were quite obviously erroneous, such as placing the ship doing 100 knots above the North York moors, and the GPS software was rejecting those out of hand. But there were others falling into what we would class as the dangerously misleading category, five metres here or there for example. That would be enough to put you on a rock or really play havoc with the precision docking systems of these larger vessels.”

The report concluded that: “There were several questions raised by this trial, such as the ability of a vessel’s crew to quickly revert to traditional means of navigation and also the extent to which they are able to navigate with these means.

“Given the greater reliance on satellite navigation, in particular GPS, these skills are not being used daily and are no longer second nature.”

According to Ploszek, “The problem would be at its worst in a crowded shipping lane with a lot of boats relying on their GPS. Imagine what could happen in the English Channel on a foggy day.”


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