Show me the way to go home

NEW technology which bypasses the sextant and the North Star offers high tech hikers and sailors a hand held navigation system…

NEW technology which bypasses the sextant and the North Star offers high tech hikers and sailors a hand held navigation system, using Earth orbiting satellites to get a fix.

The Global Positioning System (GPS) electronic compass has been available to sailors and fishing boats for some time, but now hand held models have been developed, suitable for in shore, small boat sailors and for hill walkers and trekkers.

The GPS has a receiver which picks up and interprets satellite signals, then calculates your position. The compass is about the same size as a mobile phone and can be run from a car lighter socket or torch batteries, with models available from around £180.

Up to 1,000 positions, or fixes, can be stored and the GPS will give direction, speed and estimated time of arrival. It switches easily between metric and imperial measurements. Positions are in terms of latitude and longitude, or as a grid reference for an Ordnance Survey map and most models can download onto a PC.

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On a recent hike through the Burren, I test walked the Magellan (£200 approx, four AA batteries not included). It could give an accurate position and altitude but did occasionally fail to function. Whether this is due to some malfunction or the incompetence of the handler, I don't know.

The same unit, when plugged into the 12v system of a boat in Galway Bay, worked very well, but co ordinates logged in to its memory were lost when the unit was unplugged.

The device takes a little while to understand, even with the training video, and it is easy to use up battery power getting a fix on the five satellites required for the best possible navigation. It is accurate 95 per cent of the time but the US military - which controls the system - can blur the signal up to a 100 metre error. This isn't a real problem at sea or on the flat, but users need to be wary of the same lack of precision when checking altitudes.

Be warned, though: if you can't tell east from west, a GPS isn't for you, as you need to understand the basics of navigation to interpret the information.