A map is an important navigation tool in the mountains, but only if you are able to fix your position with some certainty. If you don’t know where you are located, a map is of little use to tell you where to go. Thankfully, there are several ways to locate your position on a map without relying on a GPS unit or app. Here’s a quick guide to locating your position on a map using terrain association or compass bearings.
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Start With a USGS Topographic Map
Not all maps are equal when it comes to wilderness navigation. The gold standard to use is a US Geological Survey topographic map, which use contour lines to visualize the size and shape of the terrain, as well as rivers, trails, and other landmarks. Click here to use their Map Locator to find maps in the area you plan to visit. You can order a high-quality copy or download a PDF to print out at home for free. Using the right map is the first step for locating your position on a map.
Practice Terrain Association Skills
Before you attempt locating your position on a map, you should have some basic terrain association skill. This is the ability to look at a map and create an image in your mind of what the terrain looks like in real life – and vice versa. This is what makes it possible to look at a map, look at the terrain, and make connections and inferences between them. For example, if you see on a map, you are standing on a ridge, this is only helpful if you’re able to recognize this ridge in real life when looking up.
Practice terrain association by checking your map repeatedly as you walk, and try identifying landmarks on the map in the terrain. Before you come over ridge lines or around corners, take a moment to review the map and try to predict what terrain you will see. These are great ways to build your terrain association skills and become a better navigator.
Understanding Lines of Position (LOPs)
When trying to fix your position, most navigators rely on identifying a “Line of Position.” Essentially, the idea is to reduce uncertainty about your location by identifying lines that you must be on. For example, if you are hiking along a trail or a creek that you can see on the map, you know that you must be located somewhere along this line on the map. By identifying two different lines of position that that cross, you can pinpoint your exact location. This is called a ‘position fix.’
Identifying Natural Lines of Position
The most straightforward lines of position to use are those that already exist naturally. If you are following a trail, walking along a creek, cross a road or see power lines ahead of you, these are all natural lines of position that you can use to identify your approximate location on the map. Not all LOPs are straight, especially natural ones like rivers or trails. However, so long as you know which trail or creek you are standing near, this greatly reduces the potential places you could be.
Using a transit Line of Position
Another way to identify a Line of Position is to draw a transit – a straight line between two objects on either side of you. For example, if you’re standing in a large basin and there are two peaks directly on either side of you, you can identify these two peaks on a map and draw a line between them. So long as you correctly identified the terrain, you can be confident you are located somewhere along this line. You can also use islands or points in a lake, the tree line, large gullies, curves in the trail, river crossings, and other landmarks to draw a transit.
Using Two Lines of Position for Locating Your Position on a Map
Putting it all together, here is how you might locate your position while hiking. If you’re on a trail and you aren’t sure where you are, start looking around you for major landmarks. As you are still on trail, you already have one Line of Position. Using a small lake to your left and a large peak on the ridge to your right, you draw a line on your map that crosses the trail and realize that’s exactly where you are. You can use a GPS to confirm your accuracy, however, the best way to gain skill in navigation and terrain association is to locate your position on your own, without a GPS tool.
Using Compass Bearings to for Locating Your Position on a Map
A second method for locating your position on a map involves using a compass to take bearings on three landmarks around you. A bearing is a specific direction, like north or south, measured using degrees between 0 and 360. By taking a bearing for a landmark, you identify the exact direction it is in – which can be used to identify your own location.
Step 1: Take a bearing from a landmark
Start by taking a bearing from a visible landmark. Point your compass Direction of Travel Arrow towards the point, and turn the Compass Housing to ‘box the needle’ (match up the magnetic needle with the orienteering needle below it). The number that shows up on the Index Line is the bearing for that landmark.
Step 2: Transfer the bearing to your map
Take the compass and align one straight corner on the landmark on the map. Rotate the compass baseplate until the orienteering lines in the center run North-South and the North marker on the Compass Housing points north on the map. Draw a line along the compass from the landmark extending out ward. This is a line of position, and if you correctly took the bearing you are located somewhere along it.
Step 3: Repeat the process with two more landmarks
Finally, repeat the process by taking bearings on two more visible landmarks – preferably located at least sixty degrees apart – and transfer their bearings onto the map as well. The three lines should cross at some point and create a small triangle – your location is in this area. This is why the process is called triangulation.
Locating Your Position on a Map Without GPS: Now You Know How!
Locating your position on a map is one of the essential navigation skills for the wilderness. If you don’t know where you are located, it is close to impossible to decide where you need to go. Instead of relying on a GPS to locate your position, use terrain association, lines of position, and compass bearings. They are more dependable methods, as they don’t rely on battery strength or a satellite signal to be successful. Get out there and start practicing these skills on your next hike or climb, and safe travels on the trail!
Additional Resources for Locating Your Position on a Map Without GPS
Looking for more information and resources on this topic? Here are several articles and links that I found helpful while writing this article. If you have any suggestions for resources, share a comment below, and we might add them during our next regular article update.