Understanding the Compass
The compass is one of the oldest and most reliable navigation tools ever invented. Long before satellite navigation and smartphones, travellers, sailors and explorers relied on a compass to determine direction and find their way. Even today, it remains an essential piece of equipment for walkers, hikers, mountaineers and anyone venturing into unfamiliar countryside.
A compass works by using a magnetised needle that aligns itself with the Earth’s magnetic field, allowing you to identify the four main compass points and navigate with confidence.
The Main Parts of a Compass
Although there are several different types of compass, most modern baseplate compasses include the same essential components.
Baseplate
The clear plastic base forms the body of the compass and often includes rulers and map scales to help measure distances on paper maps.
Magnetic Needle
The magnetic needle always points towards magnetic north. The red end of the needle indicates the north-seeking direction and is the key reference when taking bearings.
Compass Housing
Also known as the compass dial, this rotating bezel contains the compass markings from 0° to 360° and the cardinal directions.
Direction of Travel Arrow
Printed on the baseplate, this arrow should always point in the direction you intend to travel.
Orienting Lines
These parallel lines inside the compass housing are used to align the compass with the north-south grid lines printed on a map.
The Four Cardinal Directions
Every compass is based around four principal directions:
- North (N)
- East (E)
- South (S)
- West (W)
Between these are the intercardinal directions:
- North-East (NE)
- South-East (SE)
- South-West (SW)
- North-West (NW)
Many compasses also divide the circle into 360 degrees, allowing for far more precise navigation.
Understanding Bearings
A bearing is a direction measured in degrees clockwise from north.
For example:
- North = 0° or 360°
- East = 90°
- South = 180°
- West = 270°
If your destination lies at 135°, you would rotate the compass housing until the bearing aligns with the direction of travel arrow before setting off.
Using bearings allows you to navigate accurately, particularly where there are few visible landmarks.
How to Use a Compass with a Map
Using a compass alongside a map is one of the most valuable navigation skills you can learn.
The basic process involves:
- Place the compass on the map.
- Align the edge of the compass with your intended route.
- Rotate the compass housing until the orienting lines match the map’s north-south grid.
- Hold the compass flat.
- Turn your body until the magnetic needle sits inside the orienting arrow.
- Follow the direction of travel arrow.
With practice, this process becomes quick and intuitive.
Magnetic North and True North
One of the most common sources of confusion is the difference between magnetic north and true north.
True north is the direction towards the geographic North Pole.
Magnetic north is the point towards which a compass needle naturally points. Because the Earth’s magnetic field changes over time, magnetic north is not fixed and differs slightly from true north.
For everyday walking and recreational navigation within the UK, this difference is usually small enough that many people do not need to adjust for it. However, for long-distance navigation or professional surveying, magnetic variation should always be taken into account.
Common Mistakes
Even experienced navigators can make errors if they become distracted or rush.
Common mistakes include:
- Holding the compass at an angle
- Standing too close to metal objects
- Forgetting to account for magnetic variation when required
- Reading the wrong end of the needle
- Walking without regularly checking direction
- Failing to orientate the map correctly
Taking a few extra moments to double-check your bearing can prevent much larger navigation errors later.
Looking After Your Compass
A quality compass requires very little maintenance, but proper care will help ensure accurate performance.
It is advisable to:
- Keep it clean and dry
- Store it away from strong magnets
- Avoid dropping it onto hard surfaces
- Protect it from excessive heat
- Check for air bubbles if using a liquid-filled compass
Most modern compasses are designed to withstand years of outdoor use when handled carefully.
Why Every Outdoor Explorer Should Carry One
Although GPS devices and mobile phones have transformed navigation, electronic equipment can fail due to poor signal, damaged batteries or adverse weather conditions. A traditional compass requires no power and continues to function in almost all environments.
Combined with a good map and a basic understanding of navigation, a compass remains one of the most dependable tools for safely exploring the countryside. Learning how to use one properly is a valuable skill that increases confidence, improves safety and helps you navigate accurately wherever your journey takes you.