It can be challenging to match a map up with the terrain, particularly when your brain has to make additional calculations about the orientation of the map relative to the landscape. At some point in our lives everyone has tried to stand on their head to make sense of whether a map is telling them to go right or left. People naturally find it easier to relate a map to the surroundings when everything that is to our left on the map matches everything that is to our left on the ground. Orientating the map in the direction of travel makes life a lot easier.
This is the key to orientating a map: placing it to line up neatly with the features on the ground. Many navigation courses make a big deal about this, claiming it’s the first thing that anyone should do before navigating. In reality, bushwalkers will rarely orientate the map accurately with a compass, unless for interest to figure out the exact names of distant peaks. Instead, they tend to orientate the map so it’s right by eye (terrain association) because it’s much quicker and flexible, and relies on the user understanding what they’re reading on the map, not just blindly following a bearing.
In short, there are two ways to orientate a map, depending on how accurate it needs to be:
- By compass
- By terrain association
Note, that the map does not need to be orientated to take a bearing from a map as the bearing is independent of the direction the map is pointing.
By Compass
1. Rest the map on level ground.
2. Rotate the compass bezel to set local magnetic declination (subtract 12.5° for Sydney, NSW area).
3. Place the compass on the map ensuring the grid lines are parallel with the edge of the compass, and that the top of the compass is pointing towards the top of the map.
4. Rotate the map and compass until the north (red) needle is sitting in the orientating arrow on the compass bezel.
Handy Tips
- Remember that compasses work using a very weak magnetic force from the earth. If any objects with a stronger magnetic force are nearby they will distort the compass reading. Make sure that you are not near metal or power lines when using a compass. (e.g. never try using a compass on the hood of a car). Some regions of the earth have high iron content in their rocks making using a compass impossible. The easiest way of telling this is if the compass needle swings erratically, and never points consistently in the same direction, regardless of anything you do!
- Generally, map orientation only needs to be accurate within a few degrees. Most of the time you can leave the compass with the magnetic variation set inside your map case and orientate the map whilst you are standing.
By Terrain Association
Terrain association is just matching the visible surroundings to the map. It is the most common method that bushwalkers use to orientate a map, but requires a good understanding of how to map read and translate features into real landforms. For this method to work, the user must know their approximate location.
Bushwalkers can determine map orientation by matching contours, comparing vegetation to that depicted on the map, constructed features (shapes of buildings, directions of roads) and hydrography (shape and size of lakes in conjunction with the size and direction of flow of the rivers and streams).
Handy Tip
Generally, bushwalkers use some combination of compass use and terrain association. Usually, they use the compass to get a rough idea of the lay of the land, then fine tune it by matching specific land features to the map. The best way to find out what works for you is to get out there and try!