Navigation is the foundation skill of hillwalking. Everything else, choice of route, decision-making in bad weather, getting home safely, depends on knowing where you are and being able to work out how to get where you’re going.
The good news is that map and compass navigation is not complicated. The principles are simple and can be learned by anyone. What takes time is practice, the ability to read terrain quickly and navigate fluently comes from time spent on the hill with a map in your hand.
This guide covers the essentials. It won’t replace a navigation course (which is worth doing), but it gives you a solid foundation to start practising.
Understanding Your OS Map
Map Scale and What It Means
UK hillwalkers use Ordnance Survey Explorer maps at 1:25,000 scale. This means 1cm on the map represents 25,000cm (250 metres) on the ground. The grid squares on an OS map are 1km × 1km. Four grid squares across = 4km.
Knowing this means you can quickly estimate distances: count the grid squares your route covers and multiply by 1km. For more precise measurement, use the roamer scale printed on most compass baseplates.
Reading Contour Lines
Contour lines are the brown lines on an OS map that connect points of equal height. On a 1:25,000 map, contour lines are drawn at 10-metre intervals (with thicker index contours every 50 metres, labelled with the height).
Key principles: - Close together = steep. The closer the lines, the more height change per horizontal distance. - Far apart = gentle slope or flat ground. - Circles = hill summits or depressions (check the height numbers to tell which). - V-shapes pointing uphill = valleys or gullies. V-shapes pointing downhill = ridges. - Re-entrants are small valleys cut into a hillside, frequently used as navigation features.
Learning to read contours takes practice. The best exercise: stand on a hillside with your map, identify three or four features around you (the ridge above, the valley to your left, the summit ahead), and find each one on the map. Do this repeatedly until the translation between map and ground becomes automatic.
Grid References
A grid reference identifies a specific point on the OS map using the national grid system. For hillwalking, use a six-figure grid reference:
- Find the easting (east-west position) by reading the grid number on the bottom of your map square, then estimate tenths across.
- Find the northing (north-south position) by reading the grid number on the left side of your map square, then estimate tenths up.
- A six-figure reference looks like: 327 415
For greater precision, an eight-figure reference adds a further digit to both easting and northing (e.g., 3274 4153), pinpointing a location to 10 metres.
Using a Compass
Parts of a Compass
A baseplate compass (Silva, Suunto, etc.) has several key components:
- Magnetic needle, the red end points (approximately) north
- Rotating bezel, the outer ring marked in degrees 0–360
- Orienting arrow, the arrow in the bottom of the capsule that you align with north
- Direction of travel arrow, on the baseplate, pointing away from you
- Baseplate edge, used for drawing lines on the map
Setting a Bearing from the Map
This is the most important navigation technique. It lets you set a direction of travel from your current position to a target feature, then follow that direction on the ground regardless of visibility.
Place the compass on the map with one long edge connecting your current position and your target destination. The direction of travel arrow should point from you towards your target.
Rotate the bezel until the orienting lines inside the capsule are parallel to the north-south grid lines on the map, with the orienting arrow pointing to north (the top of the map). Ignore the magnetic needle at this stage.
Remove the compass from the map and hold it horizontally in front of you.
Rotate your body (not the bezel) until the red end of the magnetic needle sits inside the orienting arrow (“red in the shed”). The direction of travel arrow now points towards your destination.
Walk in the direction of travel arrow, picking a landmark ahead on that line and walking to it, then repeating.
Magnetic Variation
In the UK, magnetic north is slightly west of grid north. The current variation is around 0°–2° depending on your location (it changes gradually each year and the exact value is printed on your OS map). For most hillwalking purposes this difference is small enough to ignore. If you’re navigating precisely in poor visibility, apply the correction: add the variation to your grid bearing when converting to a magnetic bearing.
Key Navigation Techniques
Handrails
A handrail is a linear feature, a wall, fence, stream, path, or ridge, that you can follow to your destination without taking a compass bearing. Wherever possible, navigate along handrails rather than on a bearing: it’s faster, more reliable, and lets you move confidently without constant compass checking.
Planning your route to use handrails where available is a mark of good navigation.
Collecting Features
A collecting feature is something you can’t miss, a wall across your line of travel, a valley bottom, a distinctive summit, that tells you you’ve gone far enough or confirms you’re on the right route. Always identify your collecting feature before leaving a known point.
Attack Points
When your target is a small, easy-to-miss feature (a path junction, a summit cairn, a tarn), navigate first to a larger, easier-to-find nearby feature, then use a short, precise bearing to your actual target from there. The large feature is your attack point.
Timing and Pacing
Naismith’s Rule estimates walking time: 1 hour per 5km of distance, plus 1 minute per 10m of ascent. Add extra time for rough ground, poor visibility, or a tired group.
Pacing estimates distance covered. Count your double paces (every time your right foot hits the ground) per 100m. Most adults are around 62–68 double paces on flat ground; more on ascents, fewer on descents. Know your own pace count, practice on a known 100m stretch.
Taking a Back Bearing
If you need to check you haven’t drifted off course, take a back bearing from a feature behind you. Add or subtract 180° from your outward bearing and look back along the direction of travel arrow. If the feature behind sits on that line, you’re on course.
Putting It Together: A Navigation Routine
Good navigators work continuously, not just when they’re lost. Develop a routine:
- Before leaving each checkpoint: identify your next target, estimate distance and time, set a bearing if needed, identify your collecting feature.
- While walking: count paces for short sections in poor visibility, note landmarks as you pass them, check the time against your estimate.
- On arrival: confirm your location before moving on. Don’t guess, if you’re uncertain, stop and work it out before continuing.
The most common navigation error is moving on before confirming your position. Time spent stopped is almost always recovered by not getting lost.