All you need is a simple baseplate compass – nothing fancy. A baseplate compass can be placed on your map – you can see through the base. This is the most important characteristic of a baseplate compass.
It will have a ‘direction of travel’ arrow on the base and ring that turns. On the ring are numbers – 360 degrees for a circle. Every 20 degrees is printed in addition to N for North, E for East, S for South and W for West. There are also subdivision marks in two-degree intervals with the 10th degree being a slightly longer line. And then there’s the compass needle, which will be painted red on one side – that side points North. Stick with good orienteering brands like Silva and Suunto because they have quality pins on which the needle rotates – the most important part of the compass because it takes a lot of jiggling.
As you turn the ring, you’ll notice that there are lines on the bottom of the ring that move with the ring when it is turned. These lines are the ones that you’ll line up with your magnetic North line on your map.
Most baseplate compasses will have various rulers on the side of the compass and a lanyard. A more orienteering-specific compass will have a stencil of a triangle (start) and circle (controls) in the base and it may have a magnifying glass too. The magnifying glass can be great for tricky maps with lots of detail but the stencils are mostly novelties because it is faster to draw freehand.
Some have glow-in-the-dark needles but they’re unnecessary because you’re going to need to turn your headlamp on to read your map…
Although they look fancy, those chunky army-style compasses and mirror compasses are not necessary. The point of the mirror is so that you can see the landscape in the background and the compass face (by means of the mirror) for sighting a bearing. In orienteering this is unnecessary and too slow.
Finally, don’t be roped into compasses with adjustable declination needles inside the ring either. Orienteering maps are drawn to Magnetic North; topographical maps are drawn to True North. But, they have a TN-MN ‘diagram’ on the bottom left to show where Magnetic North lies. Extend this arrow and use it to draw parallel Magnetic North lines across your map at intervals. Et voila! You now have a map with Magnetic North line.
You best bet is to keep it simple and remember that navigation is a critical discipline in adventure racing, as much (if not more so) as running, biking and paddling. Orienteering events are the best means to practise your navigation skills regularly and to become fluent and accurate in using a compass.