Introduction
A compass is a relatively simple navigation tool, but using it accurately requires an understanding of how its individual components work and how they interact with a map and the surrounding landscape.
The following sections work progressively through the main components and techniques used in compass navigation. They begin with the base plate, rotating housing (bezel) and magnetic needle, before moving into practical skills including orientating the map, taking and following a bearing, taking bearings from the landscape, plotting bearings onto a map, resection and back bearings.
Photographs, maps and diagrams are used throughout to demonstrate each technique and to show the relationship between the compass, the map and features in the landscape.
Some sections also include a Deep Dive button. These optional sections explore particular topics in greater technical detail, providing additional explanation of the principles, geometry and calculations behind some of the techniques. They are not essential to understanding the basic procedure, but may be useful if you want to explore why a technique works, not simply how to perform it.
Important Note
All bearings, angles, bearing lines and other navigational information shown in these photographs, maps and diagrams are provided for demonstration and teaching purposes only. They should not be copied or relied upon for navigation in the field.
Conditions, locations and observations will vary. When navigating, you should take your own bearings in the field and make your own measurements from the map you are actually using, applying the appropriate magnetic declination where required.
The examples in these sections are intended to teach how to use the techniques, not to provide bearings for you to follow.
Section 1. The Base Plate
This is the foundation of the compass. Every other component is built onto the base plate, making it the part you hold in your hand whenever you navigate.
Although it may appear to be nothing more than a piece of clear plastic, the base plate performs several important functions. It provides a straight edge for drawing bearings on the map, incorporates rulers for measuring distance, and remains transparent so you can clearly see the map beneath it while working.
The base plate itself never moves. Every fixed component of the compass is attached to it, while the rotating housing and the magnetic needle operate independently above it.
Before learning how to use a compass, it is important to understand which parts are fixed and which parts move. Once this is understood, every navigation task becomes much easier to learn.
Fixed components shown
Straight edge
Distance scales
Direction of travel arrow
Stencil holes
Lanyard attachment point
Bearing Index
Key point: The base plate is the stationary foundation of the compass. Everything else is either attached to it or moves in relation to it.
Base Plate (Deep Dive)
Although the base plate appears to be nothing more than a piece of clear plastic, it is one of the hardest working parts of the compass. Every navigation task begins with the base plate, whether you're planning your route at the Bluff Knoll car park before setting out or standing on the rocky summit of First Arrow wondering where to next.
The transparent design is one of its greatest strengths. When you place the compass on your Stirling Ridge Walk map, you can still see the contours, grid lines, tracks and surrounding terrain beneath it. This allows you to draw an accurate bearing between two points without hiding the very information you're trying to use. For example, when plotting a bearing from the summit of Pyungoorup Peak towards Ellen Peak, or confirming the line between Third Arrow Cave and East Pinnacle Gully, the transparent base plate allows both locations and the terrain between them to remain clearly visible.
One of the first concepts to understand is that the base plate never moves. It provides the stable foundation for the entire compass. The rotating housing turns independently above it, while the magnetic needle constantly aligns itself with magnetic north. Once you understand that the base plate remains fixed while the other components move around it, the operation of the compass becomes much easier to visualise. Every navigation task, from orientating your map to plotting a bearing or carrying out a resection, begins with this simple relationship.
The long straight edge is equally important. It allows you to draw precise bearing lines across your map and provides a reliable reference edge when aligning the compass with features in the landscape. Imagine standing near Second Arrow looking towards Ellen Peak. A long straight edge makes it much easier to accurately align the compass with the summit before transferring that bearing back onto the map. The same principle applies when standing on Bluff Knoll looking back across the entire ridge towards Ellen Peak, where small errors in alignment become much more significant over longer distances.
The direction of travel arrow is another feature that is often misunderstood. It doesn't point north and it doesn't tell you where to go on its own. Its job is simply to indicate the direction the compass is facing. Once you've correctly set a bearing, it becomes the direction of travel you physically follow across the landscape. The direction of travel arrow is an extension of the bearing index. So essentially, you can draw an imaginary straight line through the arrow point to the “Bearing lndex” and the centre point that the magnetic needle pivots on. The direction of travel arrow and the bearing index never move on the baseplate.
On the Stirling Ridge Walk, where you are frequently moving between rocky summits, narrow ridges and saddles, following the direction of travel arrow rather than chasing the magnetic needle is one of the habits that separates confident navigators from frustrated beginners.
The rulers moulded into the base plate are far more useful than many people realise. Before committing yourself to the next section of ridge, you can quickly compare alternative route options, estimate the distance between navigation points and gain a much better appreciation of how far remains before reaching features such as Eucalyptus Col or Bluff Knoll. On the Stirling Ridge Walk, however, distance is only part of the story. Two sections of ridge may measure almost the same on the map, yet one may involve straightforward walking while the other requires slow progress through steep rocky terrain, 1st Arrow being a perfect example. The ruler tells you how far you need to travel, while the contours tell you how difficult that journey is likely to be.
Romer 25000
You may also notice the small stencil holes and the lanyard attachment point. These features rarely attract much attention, but both have practical uses. The stencil holes were traditionally used to mark precise locations on a map without drawing large circles, while a simple lanyard can prevent an expensive mistake if your compass slips from your hand while scrambling around the rocks near First Arrow, Baker's Knob or any of the exposed sections of the Stirling Ridge.
Although most people focus on the magnetic needle, the base plate quietly performs the majority of the work. It supports every moving component, provides the reference edge for plotting bearings, allows measurements to be taken, keeps the map visible beneath the compass and forms the stable platform from which every navigation decision begins. Once you begin using it throughout the Stirling Ridge Walk, you'll quickly realise it is far more than simply the piece you hold in your hand. It is the foundation on which every accurate bearing is built.