Intro: How to Navigate With a Map and Compass
Alright, so everyone knows a few fundamentals of navigation- north is always up, the sun rises in the east, and compasses usually point towards magnetic north. But at some point in time, outdoor enthusiast or not, you'll want to be able to find out where you are, and where you need to go.
I decided to create this Instructable after a challenging three day backpack in Olympic National Park, located in Washington State. In 2008, our snow levels were 165% of what they usually are. This means that in July, we found snow as low as 3500'. Great for skiers, but for the casual hiker or backpacker, it makes trips just a little bit more challenging.
Lucky for us, I'm pretty comfortable with rudimentary navigation. In this Instructable, I'll explain to the best of my ability how to use a map and compass to keep you found.
P.S. My first Instructable. woot!
Step 1: Choosing a Good Map
The map is your most important tool, as you can always squeak by without a compass (not recommended!). Right now I'll stick to what kind of map you'll need, and save map features for later.
USGS maps are the standard for wilderness navigation.
A scale of 1:24000 (1 inch equals 24,000 inches) and line intervals of 50 feet make them pretty detailed.
They have WGS84 (lat/long) and UTM coordinate systems.
The 7.5minute maps are huge and can be unwieldy.
Many maps haven't been updated since 1950.
Custom Correct Maps- Exclusive To Washington
15 minute coverage
Scale is 1:62500
Derived from USGS maps, but arranged to show popular loop hikes and trails.
Updated more recently- 1990-84
Both lat/long and UTM
Only for Washington
100 foot contour lines
Green Trails Maps-
15 minute coverage
Originally based on USGS, but updated frequently.
Uses lat/long, UTM, UMS coordinates
Scale is 1:69500
Only Available for WA and OR right now, with plans for AZ CA NY and NV.
100 foot contour lines.
Essentially, be sure your map-
-Covers the entire hike.
-Has a map scale or datum that you are comfortable with.
-Includes features like roads, boundaries and streams.
For the cash-strapped, you can download USGS maps in pdf form, for free, on their [http://store.usgs.gov/b2c_usgs/usgs/maplocator/(layout=6_1_61_75&uiarea=2&ctype=areaDetails&carea=%24ROOT)/.do website].
Unfortunately, the maps are difficult to read when compressed to 8.5x11.
As you can see, I've only included maps found for Washington State (except usgs). If you've got any more favorites I'd love to expand this list.
Step 2: Choosing a Good Compass
The compass is your second most important navigation tool, but it is also the most important to get exactly right. Unfortunately, there's not much room for DIY here.
Your compass should have specific features, and they're absolutely worth a few bucks extra.
It should have:
1.A clear base plate- To see underneath the compass.
2. A sighting mirror- To sight objects at eye-level.
3. A rotating bezel, marked with 360 degrees in 2 degree increments.
4. Meridian lines- For map use.
5. Declination Adjustment and arrow- to correct for the difference between magnetic and true north.
And there are many more features. Just be sure you at least have the basics.
I personally recommend the Suunto MC-2 D ($40+). It works great, and is fairly inexpensive.
The MC-2 G (45+) is alright, and you can use it worldwide. Its more expensive and I still prefer the MC-2 D.
The Silva Ranger CL515 ($40+) is another good one.
Step 3: Taking a Bearing on a Map
This step is pretty simple. When doing any map work, be sure you ignore your compass needle and declination arrow. Those guys are only helpful when you're using the compass in relation to the world around you. For now, consider it more of a protractor.
This is the simplest of the exercises. Imagine your on a mountain lookout. You see another mountain, what heading is it?
1. Open the Compass, and lay it flat on the map.
2. Move the compass so that the base is along point A (where you are), and the mirror is along point B (the other mountain).
3. Rotate the bezel until North matches the maps north, and the meridian lines line up with a north south line (lat/ long lines, UTM grids*).
4. Read the bearing at the top of the compass.**
*The edge of the map is the ideal line. Any lines that parallel it will work too.
**On the bottom of the compass, 180degrees around, is the bearing from Point B to Point A.
Step 4: Follow a Specific Bearing on a Map
Alright, you're on a mission. You know that there's a cave filled with treasure, unmarked on your map, It's 308NW of your position.
1. Open the compass and turn the bezel to 308NW
2. Orient the compass with the clear part along your current position.
3. Turn the whole compass, keeping one edge along your position, until the compass matches the maps north, and the meridian lines match North/South lines on the map.
4.The destination is somewhere along the line created by the base of your compass.
Step 5: Taking a Bearing on a Real Object
Before we use your compass, we'll have to set the declination.
First, find the declination in your are by visiting NOAA Geomagnetic Data
Then, follow the directions that came with your compass to set the declination properly.
Now you can take a bearing on a real object.
1. Choose an object to take a bearing to. Ideally this is something you can do, then reference on a map. But you can practice with objects that are a minimum of twenty feet away.
2. Stand well clear of your computer. Large, metal objects usually mess up compass readings.
3. Tilt your mirror ~45 degrees in relation to the base.
4. Hold the compass outward, level, relaxed, and at eye level.
5. Close your non-dominant eye.
6. Match the object up in the compass sights. Be sure its level!
7. Turn the bezel until the north (red) needle is in the declination arrow.
8. Read the heading from the bezel.
9. Give the bezel a spin, rinse, repeat.
Step 6: Following a Bearing in Real-Life
Woohoo! You know your campsite is only a mile away, at heading 40NE. But how do you translate the heading into an actual direction?
1. Dial the bearing in on your compass.
2. Set the sight mirror at ~45degrees, hold it level, and bring it to eye-level.
3. Close your non-dominant eye.
4. Turn your body until the north needle is within the declination arrow or box.
5. Take note of an object on that heading. Choose a peculiar tree, peak, or anything else in your direction of travel.
6. Head to that object, then re-shoot your bearing.
Shoot the bearing, then have a partner travel in that direction until he's just at the edge of your sight distance. Once he's there, tell him to move left or right to get him aligned. Move to your partner, then repeat. It's a great method if you need to be super accurate.
Step 7: Conclusion
Woot! Hopefully you just learned four new skills. I'm not an expert, but those few things are enough to keep most people out of trouble.
The easiest place to practice is around home... it may be worth finding a partner to check on your work. If you head out to the wilderness, find a spot where you can pick out a bunch of landmarks. Shoot them with the compass, then compare your bearings to the actual bearings on the map.
I'd love input on this instructable, I plan on using this as a base to build on other topics, like map reading, advanced compass use, and map in hand with GPS.
Remember the best way to avoid getting lost is to stay found. Have fun!
Acknowledgments- Mountaineering: The Freedom of the Hills 7th Edition
If you're serious about the outdoors, the book is a great reference.