Navigation Techniques

Aiming Off

Intentionally aiming to the left or right of your intended destination to a nearby linear feature (handrail), so you have a known direction to turn once the handrail is reached. See 3min 18sec YouTube video here . For example, if you are heading on a compass bearing directly for the cars on a road, you may arrive at the road but miss the cars. You would not know which direction to turn to reach the cars. If you intentionally set your compass bearing to the left of the cars, you could confidently turn right on reaching the road.

Attack Point

A point near your objective, easily identified on both map and on the ground, used to guide you to your intended destination. See 3min 2sec YouTube video here . For example, you are wanting to reach a hut in a forest. You identify a nearby creek junction and navigate to that. Once there, the hut will be much closer and easier to find. As another example, after setting your compass bearing to your destination, look on the skyline in the same direction for a distinct feature (eg. hill or saddle) and walk towards it.

Conversion between Grid and Magnetic Bearings

In all but the south-west part of Western Australia:

Grid to Magnetic, Subtract the grid-magnetic angle (memory mneumonic "Get More Sausages")
Magnetic to Grid, Add the grid-magnetic angle (memory mneumonic "MGA" - the old sports car)

The good oil on magnetic declination in Australia, lifted from GeoScience Australia's Australian Geomagnetic Reference Field Values:


The red lines are isogonals, lines joining places with equal magnetic variation. They do not, as is sometimes supposed, themselves point in the direction of Magnetic North. It might be expected that isogonals would follow a regular pattern but the earth’s magnetic field at any point is affected by the land and mountain masses and the presence of metallic ores. Therefore, the isogonals are pulled out of shape and follow no regular pattern.

More importantly, check out your map for total accuracy:

Although, in reality, with compass accuracy around 1-2° (depending on your eyesight and manual dexterity), an approximation over short navigation bounds is fine.

Catching Feature

A feature past your intended destination that lets you know you have gone too far. If you miss the intended destination, the catching feature will assist in guiding you back to your destination. See 3min 51sec YouTube video here .

Handrail

A handrail is a natural or man-made linear feature which assists in navigation. Examples are tracks, sharp-topped spurs or ridges, fence lines, creeks, cliff lines. Creek lines are not always easy going, but it may be possible to travel parallel, just out of the denser scrub.

Map Reading and Navigation Knowledge Quiz

Want to try a little quiz to check/update your knowledge? Click here (~2MB) and go to Section 5.

Here's another set of questions and answers, from the Melbourne Bushwalkers.

North from the Sun and your Watch

  1. If watch set to daylight savings, convert it to standard time
  2. When South of the Tropic of Capricorn, hold the watch with 12 pointing to the sun (check by ensuring that the shadow of a vertical stick falls along the 12 axis)
  3. NORTH is found by bisecting the angle between 12 and the hour hand.

Resection/Triangulation - Back Bearings - Where Am I?

So you're not sure where you are. You can find your position on your map by using known points of reference.

  1. Identify 2 (prefereably 3) features on your map and on the ground, as widely spread as possible
  2. Using your compass, take the magnetic bearing from your location to a feature
  3. Convert the bearing to a back bearing by adding or subtracting 180° (ie. if your magnetic bearing is 180° or less, then add 180°; if your magnetic bearing is greater than 180°, then subtract 180°)
  4. Convert the magnetic back bearing to a grid bearing (eg. around Canberra/Eastern Australia, add the grid-magnetic angle. Remember MGA)
  5. Plot the bearing on your map from the known feature by drawing a line from it in the direction of the calculated grid bearing
  6. Repeat steps 2-5 for the remaining features
  7. Theoretically, your location will be the point where the lines meet. In practice, the result is usually a small triangle (when 3 back bearings are used), and your location is maybe somewhere within that triangle (you are only inside the triangle if your error for each of the 3 bearings is in the same direction. The only safe bet is to say that you are somewhere near the fattest part of the triangle).

The SUBW paper has a more practical 'real world resection' at section 2.8.3.

... more to come

Other Web-based Navigation Information

This one, from Sydney University Bushwalkers, is very good!

This one from Emergency Management Australia, not updated since 2003.

References

1 Finding Your Way in the Bush - How to navigate and paln bushwalks by George Carter, CBC, 2007. Contains some excellent techniques. This book is available for purchase from the Canberra Bushwalking Club here .

2 Bushwalking and Ski Touring Leadership, Bushwalking and Mountaincraft Training Advisory Board Inc, 2000

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This page last updated 1Jan12