When deciding to go hiking, camping or just for a walk in the wilderness, it is best to have a compass with you for safe measure. And you need to know how to adjust your compass’ declination angle in case it happens while you’re out there, in the middle of nowhere.
GPS and other navigation technology are much more advanced than they used to be, adjusting their compass’ declination automatically. However, there is no guarantee they won’t breakdown in the middle of a trip.
No matter how skilled of a hiker you are, it is always best to learn or brush up on your compass knowledge skills. This guide will teach you everything you need to know about keeping your compass pointed in the right direction.
Learning how to use a compass and adjust your compass’ declination on your own, will prove to be great help when out into the wilderness and you will enjoy your adventure more knowing all these.
Instructions to Adjust Your Compass’ Declination
The process of adjusting your compass declination may seem difficult at first, but once you’ve practiced these steps a few times in different location, you’ll become a natural.
So don’t leave home without a compass and make sure you know all these steps before adventuring into the next forest you see.
Locate The Magnetic Declination Angle
The magnetic north pole changes depending on where you are located. In the United States the declination angle ranges from 26 degrees East in Alaska to 21 degrees West in Maine.
It is important to know the declination angle before starting a trip, or to at least know how to find out what the angle is upon arriving at your starting destination.
There are a couple of different ways to look up a location’s magnetic declination angle:
- Look it up online
- Use a Topographic Map
There are websites that list a city’s latitude, longitude, and magnetic declination angle, which makes it possible to look up an area’s declination angle ahead of time. An website doesn’t always help, it depends on the situation and the area you are heading to.
You can use a topographic map, if the websites are not helpful. They have a lot of essential information printed on them, including the declination angle.
The angle should be located on the lower left part of the map, might look like a 2D compass with one arrow pointing East or West. The other version can look like an ordinary angle, made of two lines, that will help you adjust the declination angle. Read our article about how to make sure you packed everything you need.
Read The Declination Angle
For the most part, reading the declination angle on a map is simple. If the declination angle is printed to look like a compass, the angle degree will be in the middle and will look something like this: Approximate Var 2°15’ W. The first number represents the declination angle, the second number represents minutes, and the letter represents east or west.
If the declination angle looks like a regular angle, the straight arrow represents the geographical north pole, and the other arrow represents the magnetic north pole. Typically, GN and MN will be printed above the appropriate arrow. This is what you need to know about this kind of topographic map:
- An arrow pointing to the left means the declination angle is to the west
- An arrow pointing to the right means the declination angle is to east.
- The angle degree may be listed as just a whole number, printed next to or in the angle.
- The angle degree may also be listed as a whole number over distance. For example: 2°15’/130 MILS.
When hiking, make sure you have an update map of the are with you. The newer map versions have less errors on them and their declination angle is more trustworthy.
Recalculate The Declination Angle
Unfortunately, the declination angle changes every year. This means taking the time to recalculate the declination angle before starting your hike is incredibly important. Topographical maps should have the year the map was printed, as well as the yearly declination change, listed next to the declination angle.
To make calculating the declination angle seem simpler, this section will reference the example used in step 2: 2°15’ W. Pretend the map is from 2018 and that the declination angle changes a positive 7 degrees each year, which means the angle increases each year. Here is how to calculate the new angle:
- First multiple the angle change by how old the map is. In this case the map is four years old. Multiple 7 x 4 = 28
- Then add the overall angle change to the second number (minutes). Add 28’ + 15’ = 43’.
- The new angle would be 2°43’ W.
Now pretend the angle is a negative 7 degrees, which means the angle is decreasing each year. Here is how to calculate the new angle:
- This step is the same. Multiply 7 x 4 =28.
- Now subtract the overall angle change. 15’ – 28’ = 47’.
- The new angle would be 1°47’ W.
Unfortunately, recalculating the current declination angle is not always this simple. The angle does not consistently change each year, so calculating the angle this way will only provide a close estimate. Getting a 100% accurate number will require looking up every angle change that has happened in previous years.
For those who are not good at math, looking up examples to practice on is a good idea. This way you won’t have any doubts about your ability to navigate correctly. It may also be a good idea to consult an expert, or to just purchase an updated map.
Adjust Compass Declination Using An Adjustable Compass
Now that you know how to find and calculate the declination, it is time to make the proper adjustments on your compass. Not all compasses come with a dial or screw that allows you to adjust the orienting arrow, which is the arrow that points north.
If you don’t have an adjustable compass, you will end up having to think a little harder about which direction is actually north. If you don’t have an adjustable compass, go ahead and skip to the next step, as this section won’t be much help.
Adjusting your compass will be the easiest part of your trip, as it only requires moving the orienting arrow. Before adjusting the angle, take a quick look at your compass. Notice that the orienting arrow is pointed at 0°, due north. While it will probably be rare that you travel due north, it is still a part of hiking to remain aware of.
To adjust the angle on your compass, follow these steps:
- Turn the compass over.
- Locate the screw, dial, or other method, that allows you to adjust the arrow.
- Most compasses come with an attached, flat screwdriver. Use that to turn the dial.
- If the angle is East, turn the dial so the orienting arrow points to the left. When you turn your compass back to the front, the arrow should be pointing to the right.
- If the angle is West, turn the dial so the orienting arrow points to the right. When you turn your compass back to the front, the arrow should be pointing to the left.
- Turn the compass back to the front
- Line the red part of the compass needle up with the newly adjusted orienting arrow. Now the compass is pointing at your new, correct north.
Now that your compass is pointing in the right direction, you are all set to start your trip. The best part is you won’t have to adjust your compass again, unless you are traveling to a different location that has a different declination angle.
If you are not sure of your new location’s declination angle, just look at your map. If you will be remaining within the map’s grid the angle will remain the same. If you are traveling outside the map’s grid you will need another map with information appropriate to that location.
Adjust Compass Declination Using A Regular Compass
If you don’t have an adjustable compass, don’t fret. They look basically the same. The main difference between an adjustable and a nonadjustable compass will become more noticeable when you start to navigate.
Here is how to adjust magnetic declination on a nonadjustable compass:
- Notice how the pointer index and the N on the bezel (the white ring with directions and lines printed on it) line up. This indicates that the compass has not been adjusted.
- Turn the bezel ring so that the N lines up with the declination angle. For example, if the angle is 15°W, turn the ring so that the N is pointing 15° to the west.
- When the angle is to the east, turn the bezel ring clockwise
- When the angle is to the west, turn the bezel ring counter clockwise.
- Line the red part of the compass needle up with your adjusted north.
Now the difference between an adjustable compass and a nonadjustable compass is where north is pointing, which will affect how you navigate. With an adjustable compass, the pointer index and the N will still line up, even after you have adjusted for magnetic declination.
This means when you use your compass with your map, your compass is already lined up with the directions on your map, making navigation much easier. However, with a nonadjustable compass you have adjusted where north is located, which means the pointer index and the N no longer line up.
Therefore, when looking at a map you will have to turn your compass until it matches the same direction north is on the map. This makes navigation more difficult, as it will require more calculations to make sure you are going in the right direction.
Terms You Should Know About Your Compass
If you traveled before, without the need of a compass or a map, you might need to brush up on the terms used for these situations. Your compass has much more to it than just a few cardinal points and arrows.
Geographical North Pole vs. Magnetic North Pole
For those who are not avid hikers, the difference between the geographical north pole and the magnetic north pole might not sound like a big deal. However, the difference is more important than you might realize.
A compass does not point due north. Due north refers to the geographic north pole, which is determined by the Earth’s axial rotation. The geographic north pole is what a map’s compass refers to.
So, if a compass does not point towards the geographical north pole, then what does it point to? The answer is magnetic north. The reason the two north poles are not the same, is because the magnetic north pole is not in line with Earth’s axial rotation and it is dependent on location.
For example, the magnetic north pole in Florida is going to be different than the magnetic north pole in Washington.
The difference between the geographical north pole and the magnetic north pole is referred to as magnetic declination, compass declination, or declination for short. While knowing the exact wording to use may not be life-or-death, knowing what magnetic declination is could be.
Individuals who are not aware of magnetic declination could find themselves lost in unfamiliar territory. Therefore, it is important to not only know what compass declination is, but how to correctly navigate despite it.
Calculating compass declination might sound overwhelming, but this how to adjust compass declination guide will break each step down. In no time adjusting your compass will seem easy.
Do you need declination adjustment compass?
Yes, it’s necessary to adjust our compass for declination in order to take accurate readings, because our maps reflect True North, which is changing depending on where you are.
How do you set true north on a compass?
When the needle and orienting arrow line up, the direction of travel arrow on the base will point true north.
How do I find my compass declination?
The degrees of declination for an area are usually located on the bottom margin of the map near the north arrow, or they can be located using a declination chart.
Adjusting your compass to compensate for magnetic declination is easy. It only requires the turning of a dial or a ring to make sure your compass is always pointing you in the right direction. It is knowing what the declination angle is, that can get slightly confusing.
Finding and calculating the angle can be difficult as well. However, with the step-by-step process this guide has provided, it won’t take long for you to become a master at it. All it takes is a little practice to make calculating and adjusting magnetic declination seem like second nature.
Learning about your compass is the first step in assuring you will have a hard time getting lost. You can learn a few more tricks in case you do need to spend more time out there, that will help you survive in the wild.
Daniel is a gear freak when it comes to hiking, climbing and camping. He went to REI Outdoor School to meet new people and learn best practices. Don’t even try to argue with him about the latest backpack or ice axe, he tried most of them. Daniel’s dream is to climb Mount Everest.