Using A Compass

There's a lot more to using a compass than knowing that the needle will always point to the north. If you're wilderness hiking, your life could be on the line if you don't know how to use a compass and map.

Magnetic Declination

A compass needle lines up with the earth in a direction called magnetic north. True north, on the other hand, is the direction from a given location to the north pole. And because of the nature of the earth, true north varies from one location to another. The angle between magnetic north and true north is called magnetic declination.

You'll need to know the magnetic declination (or degree of variance between true and magnetic north) for the location where you're hiking, so that you can set the compass for an accurate reading.

If you're hiking in the USA and you know the zip code of the area where you'll be hiking, this web site will calculate your necessary magnetic declination adjustment online. Just type in the zip code and click on the "get location" button.

Magnetic declination will also be indicated on a topographic map, or if you're hiking in a park or National Forest, it's a good habit to ask for it at the visitor center.

Do You Know How To Use A Compass?

A lot of people might answer, "Yes...well sort of", or "If I had to, I think I could figure it out." The truth is, there's a lot more to using a compass than you might think.

Here's a useful and fairly straightforward web page with some basic directions and demonstrations on just one aspect of using a compass and map.

If you're a beginner, these instructions will likely seem too advanced.

Don't count on this, or any web page to be able to give you the instructions that you need.

There's too much at stake (your life.) The best solution is to take an orienteering course, join a hiking club and get someone knowledgeable to show you, or buy and study a good handbook on using a compass.

How We Use Our Compass

Because most of our hiking is on established trails, we pull out our compass more often at the campsite than on a hike.

When we're sitting around admiring the scenery, invariably we'll be curious as to what a certain distant landmark might be. We often don't have the topo map but the park map or even the road map of the area will name the most important features, so it will suffice.

Using a compass to identify what we're looking at in our view is just a fun campsite activity for us, at the same time, giving us practice at map and compass use.

From our own experience, here are 3 different ways that we use a compass. I'm sure there are other uses as well.

Identify distant landmarks: Knowing our location, we first pinpoint that on the map. We take a bearing to a high point or distinguishable feature we see in the distance and then, looking at the map, draw the line to see what that landmark is called on the map.
Find our location: (The opposite to the above) We look at the world and find 2 or 3 landmarks that we recognize. We take a bearing to these with the compass. Finding them on the map, we draw the bearing line from each to determine the location where we are standing. (Where the lines intersect.) For the best accuracy the landmarks should be at least 90 degrees from each other, and having 3 bearings will give more accurate results than 2.
Getting to a destination: We pinpoint where we are on the map and our desired destination on the map. From there we determine the direction we need to hike to get there.

Even though it may be miles away, and you can't see it, you can get to your destination (or close to it) one identifiable marker at a time, by finding something... a distinguishable tree, a rock, that's within your view and in the exact direction of your target. Walk to it before taking another reading to continue to the next marker in your path. Continue until you reach your destination.

Note that this is not likely to result in complete accuracy, but it will work fine for a large target such as a lake, river, road or mountain.

After you've mastered the basics of how to take readings, it's a good idea to practice using a compass by trying each of the above methods several times as an exercise.

Preparations Before Off-Trail Hiking

In every case mentioned above, you have to have a map and know a few facts before the compass will do you much good. You need to know where you are, where your destination is on the map, or be able to find at least 2 identifiable landmarks in the real world that are marked on the map.

Carrying the compass and map "in case you get lost" just won't cut it. Before heading out for any off-trail hiking you should:

Study the map. Pinpoint your starting and destination locations and identify at 2 least landmarks in the distance that you'll be able to use as a reference. Got all that? Now, carrying your compass and knowing how to use it, you can set out with extra confidence.
Note the nearest roads, trails, rivers or streams, what direction they run and where they are in relation to where you're going to hike. If you do get lost, finding other humans, even it means walking farther and perhaps in the opposite direction from your campsite or vehicle, can be enough to save your life.
Know approximately how far you walk in 1/2 hour. (See below)
Wear a watch and carry a pencil and notepad . On the notepad make regular entries recording the direction (compass bearing) and time you spent walking. With this information you can guess your location. Using a compass where there are no landmarks, involves dead reckoning, (or guessing.) You are bound to have errors and the more educated your guess, the closer you will be to your target.

As you can imagine, hiking in a forest you'll have very little opportunity to sight your compass off distant landmarks and have to rely on the dead reckoning method. Practice using a compass on flat open terrain. Deserts are the perfect place.

For other non-technical, innovative, and frugal navigational tips, please visit my desert hiking web page.

Choosing A Compass

There are several different types of compasses suitable for hiking available on the market. To make using a compass easier, here are some of the features you may want to consider:

A Base Plate Compass: This simply means it has a clear base on it so you can line it up easily and still see through the base while it's placed on your map.
Sighting Mirror: A folding mirror, which allows you to see the compass capsule while viewing your target.
Declination Adjustment: You definitely want this feature. Once you set the declination, you can use the compass normally and your reading will be accurate for true north as opposed to magnetic north.

For a beginner, using a compass can be frustrating enough. As well as increasing your accuracy, these features should save you some of the frustration.

This page is an overview on what we know about using a compass. It's not intended to provide the instructions needed by a beginner for taking accurate bearings and the transferring of information to the map. Since the amount of pages it would take to convey this information is beyond the scope of this website, I recommend hands-on training or a good guidebook.