How to Use a Compass
Maybe you’ve been to a national park or traversed backcountry hiking trails plenty of times and haven’t yet found any reason to add a compass to your hiking gear yet. It may seem like outdated technology, but a compass is essential to have with you in the great outdoors to help find a campsite or a trailhead and make sure you aren’t lost when you go into the wild. If you aren’t familiar with how to use a compass yet, don’t worry.
It isn’t incredibly difficult to use a compass for navigation, but you should know that it isn’t quite as simple as a red needle that always points north. For one thing, the north the red needle points to isn’t true north, but rather magnetic north. Measuring the difference between magnetic north and true north is something called declination and any compass worth its (comparatively light) weight will have an orienting arrow to help you set the right declination for your area.
Younger campers and hikers may be compulsively reaching into their pockets to take out their cell phones, imagining that they can skip over this how-to guide because somebody clever already but an easy digital compass on it. That may work fine, but knowing how to use a real, magnetic compass will help you use the digital variety and spare you some grief if you can’t charge your phone next time you’re out in the backcountry. Getting your bearings is really useful if you want to truly explore the great outdoors or go trailblazing without losing your campsite and getting into some serious trouble.
There are a few parts to a compass that you’ll need to know if you want to use it correctly. Once you get the hang of it, though, you’ll feel like an explorer as you make your own way through the wilderness. Backpackers who want to share their experiences or return to a particularly beautiful spot will also find it simple and convenient to mark their trail on a map to demonstrate their trailblazing prowess. Finally, if you want to break out into smaller groups on a big group camping trip, you can arrange to meet at a certain point later on without fear of losing one another. Read on to learn how to get your bearings and set your declination so you can break off the hiking trail with the confidence that you know how to use a compass.
Parts of a compass
There are several key parts to a compass and knowing what they are and what purpose they serve is a prerequisite to navigating comfortably in the wilderness. Keep in mind that these are the parts to an outdoors compass with the proper scales and orienting arrows. If you just dug grandpa’s compass out of a box in the attic, it may not have the specific parts we’re going to discuss or it may have them in a different location. You’d do well to go out and shop for a modern-day compass with the ease of use that comes from recent decades’ innovation.
The parts of a compass that are critical to know are the rotating bezel, the baseplate, the ruler, and the direction-of-travel arrow. The rotating bezel is the 360-degree ring around the compass that helps measure the degree lines. Think longitude and latitude, which is also measured in degrees, to understand the purpose of the degree markings on the rotating bezel. The baseplate is the plastic section underneath the round rotating compass section.
It should have at least one straight edge for taking bearings and it should be clear so you can see the map underneath it. The rulers look just like the ones you remember from your school days and you use them to measure distances on the map. The direction-of-travel arrow, as you may have discerned, indicates the direction of travel and should be pointed in the direction you want to go in when you are navigating with a compass.
Inside the round part of the compass where the needle is, there are a few features that deserve highlighting because they’re important to the proper operation of the compass. The index line is just above the bezel and you can use it to read a bearing. Looking at the compass, you’ll notice there are orienting lines on either side and parallel with the bezel that you align with the lines of your map to make sure the orienting arrow with the north direction on the map.
The magnetized needle in the center is probably the one part of the compass you’re familiar with if you’ve only seen a compass once or twice and aren’t very familiar with its operation. Remember that this always points to magnetic north, not true north. Finally, there is an orienting arrow you can use to orient the bezel. The magnetized end of the needle, which is the red end, should fit inside this orienting arrow.
How to adjust declination on a compass
“Declination” is one of the more technical aspects involved in the operation of a compass. Since most hikers and backpackers won’t already be familiar with the word, think of declination as a kind of orientation of oneself on the earth’s surface. It’s also really important to remember that declination, which is measured in degrees, varies with the country you’re in, and also with what part of that county you’re in if it’s particularly large.
In the United States, declination varies from 16 degrees west in Maine to 4 degrees east in Texas. Declination also tends to change slightly from year to year, so you’ll have to do your research on your area’s declination before you head out. Maps usually have this information on them but an outdated map could have a declination that has become incorrect over time and steer you off course.
Declination, in brief, is the difference between true north, which is the North Pole, and magnetic north, which is a few degrees east or west depending on where you are on the planet. The good news is if you’re using your compass to hike around your hometown or in the same place over several hiking trips, you won’t have to adjust it. Declination only needs to be set if you move far enough away from the last place you used the compass.
The bad news is that different compass brands differ in how they let users adjust the declination, so you’ll need to consult the owner’s manual of your own compass to find out exactly how it works. Some use a key and others allow users to adjust to the proper declination with their fingertips. In any case, there’s no universal way, but it’s not overly complicated on any of the major models of compass.
If you haven’t invested in a compass with adjustable declination, you can simply correct for the declination by adding or subtracting (adding for the east, subtracting for west) from the true declination you find on your map. Make sure you get an up-to-date map with a current declination of the area you’re hiking so you can make necessary measurements and do the proper mathematics if your compass doesn’t allow for declination adjustment.
Reading a map for navigation
If you’re not traversing complicated terrain and there are plenty of landmarks, you can probably navigate with a map alone just by orienting yourself to a landmark and traveling in the proper direction according to the map. To avoid confusion and really make sure you know where you are and where you’re going, it’s always best to bring a compass along. In order to navigate with a map and compass the right way, you’ll want to place your compass down on the map with the direction-of-travel arrow pointing north, which should be toward the top of the map. Rotate the bezel so that the red end (north) of the magnetized needle is lined up with the direction-of-travel arrow. Slide the baseplate so that one of the edges aligns exactly with one of the edges of the map.
The final step requires some coordination so it’s not really advisable to try it next to a steep drop-off or a body of water. Take both the map and the compass in your hand and rotate your body so that the end of the magnetic arrow is aligned with the orienting arrow. With all these steps done you should be properly aligned with the map and the proper direction across the landscape.
How to take a bearing with a map and compass
You likely know the expression about getting one’s bearings and it stems from the use of a compass. A bearing is simply a direction on a map, but it’s much more detailed than simply saying left or right or east and west. Bear in mind that your bearing only matters based on the specific place where you are standing and the specific place that you are traveling to, so you will want to regain your bearings if you want to change direction or you finish one leg of your journey.
The first thing you need to do is find your exact location on the map, which you’ll have a much easier time doing if there are standout landmarks in your vicinity. Once you’ve located yourself on the map, place the compass flat on the map and align the ruler so that it makes a straight line between your current position and the location where you want to go. The direction-of-travel arrow, as you can probably guess, should be pointing toward the campsite or trailhead where you’re headed. Make sure it isn’t pointing in the wrong direction or else you won’t be able to properly navigate.
Next, rotate the bezel until the orienting lines are aligned with the left and right edges of the map. The north line on the bevel should be aimed at the top of the map. One common mistake for those not adept at using a compass is to have either the bevel’s north line or the direction-of-travel arrow pointed in the opposite direction, which can lead to navigational disasters. It’s easy to aim them the right way but also easy to overlook them if you’re distracted or more focused on your surroundings than on the map and the compass. Once you have everything aligned properly, you can use the index line to read your bearing. It may be helpful to trace this on the map for later use, your own records, or to double-check the accuracy.
Taking a bearing from your surroundings
Rather than taking a bearing on a map, you can also take a bearing based on landmarks to either reverse-engineer it on the map or if you want to keep a brisk pace and simply want to make sure you’re still on the right course. All you need to do is find your landmark and then hold your compass flat with the direction-of-travel arrow pointing away from you and toward the landmark you’re using to take your bearing. Rotate the bezel until the magnetized needle is inside the orienting arrow and then look at the index line to take your bearing.
You can trace this onto your map by aligning one corner of the compass with one corner of the ruler on top of the landmark. Leave the direction-of-travel arrow pointing in the direction of the landmark and rotate the baseplate until the orienting lines are pointing up-and-down on the map, or north-south. The north arrow on the bezel should also be pointing north. With the compass in place like so, you can trace a straight line along the edge of the ruler between the landmark and your current location. Once you gain some experience, you can find your exact location with multiple bearings if you can find the right landmarks in the surrounding scenery.
A compass is an invaluable addition to your rucksack and it will help you find your way through the backcountry. Remote campsites or trailheads will be much easier to find and you’ll be able to avoid wasting time trying to find your location or navigate unfamiliar terrain if you bring a compass and a map along and know how to use them. There’s a little compass-specific vocabulary and some mathematical skills you’ll have to get used to, but if you’re a regular hiker or backpacker then you won’t have a hard time acclimating to navigating without the use of a phone or GPS device that does all the work for you.
Ultralight backpackers shouldn’t take any issue with a compass, as it can easily be carried on a carabiner through a belt loop or in your pants pocket. There are some crucial things to remember if you’re out in the backcountry using a compass to navigate. You should make sure to pay attention to your surroundings when taking a bearing or trying to match a landmark on the map with one in real life.
There are some hazards like holes, rivers, and cliffs that can cause a hiker harm if they are walked into blindly. Secondly, you should make absolutely sure that the landmark you’ve chosen is the correct one on the map. If you’re in a national park or a well-tread area, then you aren’t too likely to get confused. But if you’re blazing your own trail, small mountains and lakes can be easily confused for others on the map.
Using a compass is one of the keystone outdoor skills that enthusiasts should learn to master so that they can really explore nature without being dependent on park staff, trail maps, or trail guides. There are many places that may have been hiked over before, but that doesn’t mean they’ve been widely noted or added to any of the usual guides or lists of hiking trails that hikers use to find the most pristine places in the backcountry.
For hikers who want to make their own way and explorers who often go out half-blindly into the wilderness and want to find landmarks on a map so they can return again someday, a compass and an up-to-date map with the right declination for the area are tools that can’t be done without. Now that you’ve finished this quick guide, you can be an explorer yourself, blazing new trails through areas of the backcountry where you perhaps didn’t dare to go before you knew how to use a map and compass.
Bonus tip: Check out this explainer on magnetic declination for beginners!