The map scales on the baseplate of Suunto compass are there to help you measure distances on the map. When the same scale is on both the map and the compass, the distance between two points can easily be read from the compass. Simply align one point to the start of the scale rotating the compass until the second point can be read from the applicable scale.
Even if your compass does not have a matching scale, you can use the available scales to make quick conversions to the map scale. Calculating distance is a key tool in tracking your speed and estimating how long it will take to get to the next landmark. If you don’t reach a landmark in the estimated time, it is a good indication you are off track and it is time to take another reading to get you back on track.
Baseplates always have a direction of travel arrow that must point in the direction you want to go both when working on the map and when moving in nature. If the travel arrow is not set correctly, you can easily end up walking in the opposite direction away from your next landmark.
Suunto compasses intended for non-military use have red baseplate prints. This helps distinguish the baseplate markings from colors used for map symbols.
Many Suunto baseplates include other additional features to make navigation with maps easier. Some have holes that can be used for marking your starting point and places you intend to go on the map. Marking and adding notes directly on your map is good practice when navigating in unknown terrain.
Other Suunto baseplates include a magnifying lens for reading map symbols.
And some of the finest Suunto compasses have skid-proof feet on the baseplate to help keep the compass in place on the map. This is a nice feature when the outdoor elements are not cooperating!