How To Read A Compass

What Is A Compass Used For?

Compasses are used to find your bearings and navigate the local area accompanied with a physical map from the likes of Ordnance Survey. Outside of aviation or military use, you'll commonly see compasses used by hikers to navigate their way around an unfamiliar trail. Compass reading is also commonly taught in Scouts as it's necessary for orienteering activities. Helvellyn and other areas of the Lake District are fantastic for an orienteering and navigational exercises thanks to a mix of scenic views and variable inclines.

Whilst you'll mainly navigate with a map and your own eyes, a compass is handy in the event that heavy rain or darkness severely limits your visibility, especially when you're in an unfamiliar area and you've wandered off the beaten track. Compasses can also be used to quickly indicate which direction the wind is blowing from.

How Does A Compass Work?

Inside the compass lies a small magnet attached to the compass needle which you'll see spinning around inside. It responds to magnetic field of our own planet. You'll often find that the container the needle is housed in is filled with liquid - this is so that the needle will move smoothly when changing direction.

The arrow of a compass will always point to the magnetic north, not to be confused with true north. However, magnetic interference can cause a compass to stop pointing towards the magnetic north and provide a false reading, so you need to be aware of your surroundings and avoid walking near things such as scrap metal or even certain rock formations. Another common cause of interference are the objects carried on your person, such as keys, wrist watches and smartphones.

Magnetic North, True North & Grid North

Compasses point to the north. However, there are a few variations of what 'north' actually means when it comes to compass reading and navigation:

Magnetic North

The magnetic north refers to the earths magnetic field, location-wise this is the magnetic north pole. This is the direction that all magnetic compasses will follow, however as the direction of the earths magnetic field changes over time, this particular type of north is less accurate of a reference to use when you're comparing with a map. In layman's terms, compasses don't necessarily point north.

True North

True north relates to the geographical location of the north pole.

Grid North

Grid north refers to the squares that a map is divided up by. Following a map northwards will lead you loosely in the direction of true north.

To learn more about the three types of north, check out this guide by Ordnance Survey.

Types Of Compass

Basic Compass

A basic compass will typically only include the cardinal directions. This is commonly seen on small sports compasses or increasingly common to see on wrist watches, some of which may also include inter-cardinal directions. They're usually one solid unit, meaning you won't be able to rotate the bezel in order to align with a map. A basic compass is only really useful if you're in a somewhat familiar area and only need a general direction to guide you back on course.

Orienteering Compass

Orienteering compasses are designed to make following a map much simpler. They're commonly known as base plate compasses in ode to their see-through flat body which allows the user to place the compass directly onto their map and see everything underneath. The flat edges also make it easier to draw lines on a map once you've found your bearing. Base plate compasses don't usually feature a compass rose due to the need for transparency, though you'll still find all of the cardinal directions on them.

Sighting Compass

Otherwise known as a hand compass, a sighting compass features a notched sight which can be used to find an exact bearing of a distant location or landmark. You'll commonly find that sighting compasses either have a mirror which reflects the compass needle and allows the user to see the bearing, or an optical plate with a reticle and bearings printed on for easy viewing.

Features Of A Compass

For modern compass reading exercises, you're most likely to encounter an orienteering compass. Here are some of the features you'll find:

Base plate
Ruler
Direction of travel arrow
Rotating bezel with degrees and cardinal directions
Orientation arrow
Magnetic compass Needle
Orienting lines
Magnifier

How To Follow A Compass

In order to travel in the right direction, you'll first need to adjust your compass accordingly. This is achieved by twisting the bezel of the compass until the orientation arrow is in line with the direction in which you want to travel (indicated by the direction of travel arrow). Next, line up the north (red) end of the magnetic compass needle with the orientation arrow in order to find your heading. This is the direction you need to walk towards.

We hope you learned something useful from reading our compass guide. If you're looking for inspiration on where to go on an orienteering trip, why not check out some of our walking guides? That way, you'll be able to pick up an Ordnance Survey map which you can reference along the way!