Navigation is essential in outdoor activities. Long ago, before modern technologies like google maps and GPS came into play. People, including hunters, anglers, sailors, hikers, and even travelers, depended on a compass and paper map to navigate. Nowadays, we are overly dependent on electronic devices. What happens when they disappoint, and you are far into your journey. In cases where the battery drains or such devices get wet, or another likely bad scenario happens. What do you do? Stay lost?
Hence the need to always have a working compass and a topographic map before taking that trip. They are still the essential tools for navigation in the wild, likewise on the sea. Having them won’t cut it; you should also know what it is and how to use it.
What is a Compass?
A compass is an instrument that shows directions and is used for navigation (finding directions). A typical compass has a needle that always points north. This needle spins depending on the path of your movement. The pivot is attached to a flat surface called the compass card. The compass card is the part that carries marked directions and angles.
The working Principle
It consists of a magnetic needle (pointer) suspended freely in the compass casing to respond to the Earth’s magnetism. As it hovers in the case, it aligns with the Earth’s magnetic field with the needle’s upper pole pointing towards the Earth’s magnetic north pole. And the lower, towards the Earth’s magnetic south pole. But basically, the north pole is used as the reference point.
Types of Compass
Broadly, there are two types of compass, namely, Magnetic Compass and Non-Magnetic Compass. These two, however, have different types depending on the make.
Magnetic Compass: It is the widely known and most used type of compass. They indicate the direction of the magnetic north. This type of compass consists of a magnetized metal that rotates freely because of low friction. Usually, the end of the needle that points northwards is marked red for easy readability. Examples of this type include the baseplate compass, card compass, thumb compass, etc.
Non-Magnetic Compass: This type of compass, unlike the magnetic compass, identifies true north and not magnetic north. The true north is the geographic north of Earth. The compass usually has a spinning wheel whose rotation interacts with the Earth’s rotation. By doing this, it can point to the true poles of the Earth. People use them in ships, astronomy, and other circumstances where there is a need for accurate identification of the geographic north rather than magnetic north.
The type of compass suitable for outdoor sports is the magnetic compass. And the common one is a baseplate compass precisely. So we will focus our usage on a baseplate.
Parts of a Compass
Baseplate: It is a flat and transparent rectangular surface that holds the map. It also has marked information on it. The information is useful for interpreting necessary data from maps for getting directions and location.
Scales: These are lines and calibrations marked on the edge of the baseplate. They show the conversion of the distance on paper to real life. To use them, you will have to set the straight edge of the baseplate on your map. With that, you can mark the distance between two points.
Direction Arrow: It is usually a small triangle that points away from the compass housing to the baseplate’s shortest edge. During navigation, this arrow is used to indicate the way you are going.
Magnifier: There is a small, circular magnifier included. It allows users to take a closer look at tiny details on a map.
Index line: This is the end of the line from the direction of the travel arrow.
Dial: This is a circle that rotates around the housing. It’s marked in degrees, going from 0 to 360 degrees.
Orienting arrow: An arrow marked on the base of the housing. It rotates along with the dial. When orienteering, it can be aligned with the magnetic needle and kept there to ensure that a user is properly following the bearing. (we will discuss this later).
Orienting lines: These are lines that run parallel to and rotate with the orienting arrow. They aid in navigation, especially when the compass is sitting on a map.
Needle: This is the thin, magnetized metal that spins with the Earth’s magnetic field and indicates the north’s direction. It’s the most crucial component of a compass.
Housing: It is enclosed and raised above the rest of the baseplate. The needle spins inside of this, and the dial rotates around it.
Functions of a compass
Navigation and direction: A compass can show you the direction you are traveling – where you are” heading” either on land or water.
It can also indicate the direction an object is from you – that is, the object’s “bearing.”
It gives you a straight path to follow.
Map orientation: A map is a representation of the real world, drawn in a specific direction. The map being directional is what is known as its orientation. To orient a map, you have to place such a map so that it’s north is pointing north. A compass can make this possible. When oriented, you can identify your location and also align the map with the actual landmarks.
Triangulation: Determining your location.
Plan trails: Using a map, you can determine the direction and distance to travel on that map.
Besides hiking or other outdoor adventures, it can also be used in building and construction, for making borderlines and other landmarks.
How to Use a Compass
A compass works best with a map. Without it, it’s not of much use. The map is where you have your route and your location, where to go. To use a compass effectively, you need to use it with a map.
You can use a compass to find either your location or your bearings. But first, before you do anything, you will need to adjust your declination.
What does this mean?
Adjusting Your Declination
Declination is the difference (angle) between the true north and the magnetic north. The compass’s needle points to the magnetic north, and it is hundreds of miles apart from the true north. Maps are oriented to the true north (geographic north). To use your compass with your map, you will have to resolve this difference (declination). If not resolved, you will always get the wrong direction.
The easiest way to find your angle of declination is by using your map.
Most maps have declination diagrams. However, the value changes over time. This means you have to be sure of the map’s revision date. If you are using an older map, you should check online.
Once you have your declination, a little calculation is required. The challenge, however, is whether to add or subtract the angle to your actual reading.
If you have a west declination, add the angle to your actual reading. If you have an east declination, subtract the angle from your actual reading.
The mnemonic for keeping this to memory is “West is Best, East is Least.”
West is best, so it is more extensive; therefore, you add to the true reading. East is least, therefore, smaller, so you subtract it from the true reading.
How to Find your Location with a Compass
First, you must find a couple of landmarks around you. Lakes and mountains are preferable and easier.
Use your compass to orient your map such that the north will be pointing to the true north. To make this easy, ensure your compass’s gridlines align with the north-south grid lines on your map.
The next thing is to take a bearing on your first landmark. To do this, align your direction of travel arrow with your landmark. After that, you can now rotate the bezel until the needle aligns with the part marked for the north. Your bearing is the number next to your index line.
Then, place your compass straightedge on the landmark ( on your map). Now, you need the needle to align with the north on the bezel. You must rotate the entire compass to achieve this. You can draw a line across the edge with a pencil.
Repeat the above procedures for your other landmarks.
Your approximate location is the point where the lines intersect.
How to Find Bearings with a Compass
Once you know your location, determining how to get to anywhere on your map is possible with your compass. As always, remember to adjust your declination before starting.
Set the corner of your baseplate on your position and rotate the compass. Stop the rotation once the straightedge forms a line between your location and destination.
Rotate the bezel to align the gridlines on the baseplate with the ones on the map.
The number next to your index line is your bearing.
To determine the direction to your destination, while holding the compass in front of you, turn your body. As you do this, your dial keeps rotating. Keep turning until the bezel aligns with the compass’ needle. Now, your direction of travel should be pointing towards your destination.
Best Practices in Using a Compass
Avoid Metals: Many people are fond of spreading their maps on the hood of their car. If you use your compass with your map (which will include you putting the compass on the map), don’t do this. Metal affects the magnetic needle.
Use Updated Maps: this is important, especially for determining your declination. Declination changes over time, which is one of the reasons maps are revised. Save yourself some troubles and get an updated one.
Use the Right Compass Model: Initially, compasses were made differently for the northern and southern hemispheres. However, there are now global compasses. Be sure to use the right compass for the right hemisphere.
Adjust Declination: Always adjust your declination before using your compass. It determines the accuracy of your readings.