Navigating with a Map and Compass
This is a companion to my GPS page.
I won't try to write a whole guide about map & compass navigation as there are already great online resources for that. Instead, I'll give a few tips I haven't found elsewhere and link to the best guides I have found. If you know other good pages or tricks, please leave a comment at the bottom of the page.
I first learned map & compass navigation in two Australian "bushwalking clubs" (hiking clubs), CMW and Sydney Bushies. Most walks in these clubs are off-track. Typically the GPS is off all the time, except when the walk leader doesn't feel so confident about what ridge or creek you're on. It must be said that the maps are not that accurate in that part of the world, because it hasn't been intensely surveyed. It's common to walk with someone who actually gave the name of a landscape feature you pass by. (Of course the Aboriginal name has been around much longer.) It also happens that you chance upon a huge waterfall that doesn't show on your 1/25k topo map, or that you discover that a feature is 200 yards from where the map shows it.
Folding maps
Before walking with bushwalking clubs, I had been nearly religious about folding my maps along their original folds so it would look as close as possible to how it was when I picked it up in the store. The clubs changed that. One thing I loved learning there was what to do with a fresh map you've just bought when you take it home.Without a GPS, a map that stays in the bag is of little use, because unless you follow your course, when you pull out the map you typically have little idea of where you are. The map is most useful when it's in a transparent plastic pouch, which can be a mere ziplock or a fancy map holder from the mountaineering shop. The first thing that you do with a map, the club elders taught me, is to change the way it folds so that the largest amount of map possible will show in your transparent pouch. How you fold will obviously depend on the size of maps in your country and the type of pouch you're using. You end up with maps folded to a size a little larger than standard sheets of printing paper, and that's how you store them.
You'll want to fold in the white areas at the edges of the map, as well as the legend and map cover, so that more map stays visible.
The next thing you do with a fresh map is to write in the UTM northing and easting numbers along the grid lines, every third box or so. When you don't have a GPS, this allows you to easily quote grid references and compare notes with your hiking partners:
"Where do you think we are, Bill?"
"I'd say 12.2, 46.9."
If you do have a GPS, the numbers you've written next to the gridlines let you know exactly where you are without having to unfold the map to read the northing and easting in the margin.
It's customary (and useful!) to mark the map's name in a corner of each fold. I suggest also marking the map datum (e.g., WGS84) in case you use a GPS and live in a place that uses multiple maps standards (like Australia).
Map-reading tips
The map-reading guides linked above have a lot of information. Here are a few things I either didn't see there or didn't see stressed enough.The Hollywood clue
The elevation figure on the contour line is typed as if it were the "Hollywood" sign standing on the mountain so that you can read it from a distance. This is a great clue to know if consecutive lines are going up or down.
Blue fingers
Streams running into bigger streams and rivers make blue "fingers" on the map. Water flows downhill, so the fingers point uphill, whereas the "wrists" are downhill.
Up a creek
It's challenging to follow a creek when walking uphill, especially a dry creekbed. Other creeks from uphill may run into the creek you're following, so it's easy to make a wrong turn. Conversely, it's easy to follow a creek downstream because streams rarely split.
Down a ridge
It's challenging to follow a ridge when walking downhill. Ridges split, so you can easily find yourself on the wrong ridge. Conversely, it's easy to follow a ridge uphill, because ridges tend to lead to the top without splitting.
What am I looking at? Triangulating with a GPS
The primers below cover the technique of "triangulation" to 1) find out where you are on the map by sighting two known objects or 2) find what a landmark is by taking a bearing to it from several spots. The same techniques can be used with a GPS and no map. The tip below explains how to find out what you're looking at using a Garmin GPS.You could take a bearing to the object to be identified, project a waypoint in that direction, then pan the map on the GPS. But how would you know how far to pan?
Here is how to obtain a precise measurement for cases when the landmark stays visible for a while.
1. Mark your spot with a waypoint: W1.
2. Project a waypoint far beyond the target: W2
3. Walk for a while and mark your new spot: W4
4. Project a new waypoint far beyond the target: W3.
Now create a route on the GPS: W1-W2-W3-W4. Then pan the map to the place where the route makes an X: that's the landmark you're trying to identify. You can make a waypoint for it by pointing the arrow on the intersection and pressing "Enter".
The further the target, the longer you want to wait between the two measures so the bearings you measure have a chance to change.
With the same technique, you can answer questions like "How far do you think it is from that pass to that lake?". You would need to make waypoints for the pass and the lake using the above procedure, then to use the "Distance" function on the device.
Navigation Primers
Wikipedia page on UTM/UPS. You'll probably be using the UTM/UPS format to make the GPS "speak" to your paper topo maps. I'd been using it for years without reading about what it was, and boy, was I missing out. I find this page fascinating and the UTM system just brilliant.Brochure published by the Australian government. Basic but good.
Guide to Map & Compass. A bit more detail about real-life situations in the bush.
Garmin guide. Good introduction.
Gorp. Good series (seven articles). However, after viewing a few pages, you'll need to register.
Map Reading Skills
How I wish I were able to look at any topo map and instantly visualize the corresponding landscape. And how I wish I were able to look at a landscape and immediately see what it would look like on a topo map.For map reading skills, try these sites:
Topo tips, a nice primer.
Topo map skills, which has a nice diagram of common features.
Reading topo maps: excerpts from Map Reading and Land Navigation, an army field manual. You can download the whole manual here.
I have also read that The Essential Wilderness Navigator is a great book on the topic.
Map Links
Map projections. For those interested in how the features of a ball (the Earth) are flattened to make a world map, this is an amazing site.Politically correct world map by Arno Peters, published by ODT. Classic worldmaps greatly distort areas maps far north and south of the Equator, making Greenland look as large as Africa. This map respects the relative size of continents and countries.
