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April 2011 Issue
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Survival skill #4 – Navigation

Photo: Andrew Johnstone
Ace navigator Tim Farrant can help you out of just about any predicament
  • I’ve got a compass, but I don’t know how to use it!

Your compass has two essential functions. Firstly, use it to orientate your map. Hold the map so that your line of sight (on the map) is in the direction that you wish to travel. Then orientate it to north by laying a compass on the map and rotating yourself (with the map) until the north arrow points to magnetic north on the map.  

The other useful function of a compass is to take bearings. To take a bearing line up the long straight edge of the compass between your current location and destination. Rotate yourself (again with the map) until the north arrow is in agreeance with magnetic north on the map. Follow in the direction that the long straight edge of the compass points.

  • I’ve lost my map, now I’m lost. How do I get to safety?

Maps are useless without a compass and if you don’t have your map, a compass won’t be much help either. Look for prominent ridgelines to travel along, or descend down them into river valleys. If possible find your way to a hut; these tend to be located on river terraces or at the tree/scrub line. Some will have maps, while others may have helpful comments in the intentions book about the route out.

  • I can’t see anything in this mist, how do I get off this mountain?

Navigation in whiteout is a challenge to even the most experienced navigator. Using your map, identify a route off the mountain via prominent ridgelines. Avoid ridges with sudden steep sections as these are prone to ‘bluffing out’ – a highly dangerous proposition in misty weather.

Take a bearing along your intended route and keep to the crest of the ridge. Continue taking bearings regularly to confirm your ridgeline route (best achieved with a map and compass in hand). Descend until visibility is restored and reassess your situation.

  • It’s night; can I use the stars to navigate by

Yes you can. If you are a keen astronomer then you will be familiar with the south celestial pole. The south celestial pole can be approximated as being the constellation Sigma Octantis, but is very dim and barely visible on a clear night. To find the star it is easiest to first find the Southern Cross then extend a line, four and a half times its length in the direction that it points. The south celestial pole and Sigma Octantis, will be very close to this position in the north sky.

But a word of caution: do not rely on stars for navigation. Stars may be obscured by cloud, tree cover or ridgelines. The most reliable navigation tool is a map with a compass.

  • I know there’s a track here somewhere, how do I find it?

In New Zealand it is not unusual for tramping tracks to become densely overgrown so you cannot simply rely on ‘stumbling’ upon the track. In fact, you may cross it at right angles yet never notice it!

With this in mind it is essential that you know your position on the map (even when a track is nearby). But if you are already lost you will need to use one of two navigation tricks: simultaneous navigation, or relocation.

For simultaneous navigation, identify two or more likely places on the map where you may be (e.g. the confluence of two minor streams with a nearby major river). Then travel confidently in any direction, noting distinct features until you can confirm that only one of the potential places you’ve identified ‘fits’ with the map. This will be the correct point from which to locate yourself.

A less technical, but more physically demanding option is to relocate yourself. Do this by removing yourself to a location where you can, with a high degree of certainty, determine your position. An example would be to travel to the nearby confluence of two major rivers and once you have confirmed your position, take a bearing and follow it closely until you meet the track. A distance measurement technique such as timing or pace counting may be useful here.

Tim Farrant is a New Zealand orienteering champion and world junior rogaine champion