Finding your way doesn’t have to be scary! Zac’s put together a beginner’s guide to navigating with a map and compass so you can get out there (and back) without a worry.
For a lot of people in the outdoors, map-and-compass navigation is an enigma. It’s one of those skills that can seem unnecessary. Even for those who like to get off the beaten track, GPS is becoming more and more popular; it’s even in our phones! But when it’s just you against the elements, any tech can be unreliable, and it’s important to be able to navigate the old-fashioned way.
The Map, Terrain & Contour Lines
Let’s start with just the topographic map. That bit of paper is invaluable: it shows you where you’re going and what you can expect. The most important part of the map is the contour lines. They’re those squiggly red lines you see everywhere.
The important thing to know is this: each contour line marks a certain height. If two points are on the same contour line, they’re the same height. All maps will also have what we call a contour interval – the vertical distance between two contour lines.
Hot tip: Always check the contour interval. A 20m contour interval makes terrain look flatter than a 10m one.
From knowing this we can tell a lot about the terrain. Are the contour lines close together? Avoid going there – it’s going to be steep. Are they further apart? It’ll be flatter there. Once you’ve got the hang of this, start thinking about what certain features will look like. Try to find the tops of hills on the map. See if you can find a valley, or a spur, or a saddle.
With practice you’ll be able to visualise the terrain and even work out where you are!
On a map, you’ll also see things like roads, tracks and vegetation. The legend tells you how to identify these. You’ll also find the scale, which lets you work out just how far apart everything is.
Getting Your Compass Bearings
Let’s quickly recap the main parts of a compass.
- The compass needle. The red end points to magnetic north (remember this – it’ll come in handy later)
- The direction of travel arrow
- The orienting arrow
- The compass housing – this rotates and has numbers on it that we can use to take bearings
- The index line – it’s hard to see, but it’s that little black line to the left of 320
Even without a map, a compass can be super useful. Say it’s raining, your hiking buddy is injured, and you need to walk out the fastest possible way. You can see a road from your vantage point at the top of a hill, but once you go into the bush it’ll be hard to make sure you’re going in the right direction.
Point the direction of travel arrow at the road and rotate the compass housing until the red end of the compass needle sits inside the orienting arrow. As long as you keep the needle on top of that arrow while you walk, you’ll eventually hit the road, even if you lose sight of it as the terrain changes.
Congrats! You just took your first bearing.
Safety Note: Off-track hiking should be reserved for emergencies and wilderness areas, even short distances can be very slow going or dangerous when you stray from the path.
Putting it all together: Navigating with Magnetic & Grid North
So you can read a map now. You can use a compass. Now we get to the bit where we put them together – this is where your newfound skills get super useful. Whether you can see a water source nearby on your map or you need to bush-bash a kilometre to get to the track, this will help you do it.
First, find your route on the map. For example, say I want to walk from the end of Peat’s Track (A) to the peak on Muogamarra Ridge (B).
Place your compass on the map, and line the long edge up with your route.
Then, rotate the compass housing so that the black lines inside it are parallel with the north-south grid lines on the map.
The number on the housing that lines up with the index line is our bearing. Now we can take the compass away from the map, with our bearing (in this case it’s 312 degrees). But there’s still one more thing to do.
Remember when we learned that the compass needle points to magnetic north? Well the lines on the map point to grid north, which is different. Your map will tell you the difference (in degrees) between them, or what we call magnetic declination.
One more thing: Magnetic north is slowly moving, so it’s worth checking the up-to-date magnetic declination for the area you’re exploring.
This is on the limit of what we can explain in this article, but these are the key points to keep in mind when swapping between your map and your compass.
- An east declination is a positive number and a west declination is a negative number.
- When you’re going from compass (magnetic bearing) to map (grid) you’ll add the declination.
- When you’re going from map to compass, you’ll subtract the declination.
In Sydney, the declination is currently 12.6 degrees east (your map will have the declination shown at the bottom of the legend). So, when we go from a map bearing (what we just took) to a magnetic field bearing (what we need), we need to subtract 12.6 degrees.
312-12.6 is 299.4, which we can round up to 300 since the scale on our housing isn’t that accurate. From here it’s the same as when we took the bearing without the map. Just turn your compass so that the compass needle spins over the orienting arrow, and away you go.
We’ve only scratched the surface of navigation here. There’s a whole world out there that includes things with scary-sounding names like back bearings and triangulation (which really aren’t that scary). Any decent navigation course will teach these and get you applying them in no time.
Geoscience Australia has a great guide to interpreting maps, too. Now though, your first priority should be to get out there and use what you’ve learnt. Pick a walk you know well, and try to navigate to features around it. Look at landmarks and try to work out where you are. Start practicing now and you’ll be a master in no time.