Within a few days of starting my Appalachian Trail thru-hike in 2002, I began dead-reckoning using my watch and the Databook. With surprising accuracy, I now had a method of monitoring my hiking pace, pinpointing my location in between known landmarks, and predicting the time it would take to reach upcoming points of interest like water sources, shelters, and road crossings.
While I quickly picked up this skill, it took many years until I achieved fully the second characteristic of an expert navigator: proficiency in my understanding and uses of my tools.
The scope and pace of my learning was mostly driven by my route’s conspicuousness and by the location’s topographic relief and visability — the very same factors that determine which navigational tools I carry and to what degree I rely on them. Bushwhacks through East Coast forests, for instance, forced me to master the compass. My map-reading skills were honed by on- and off-trail travel in the Mountain West. And skiing across Alaska’s featureless Arctic Coast gave me reason to learn GPS.
In Part I of this series I described the navigational tools that I use. In this post I will explain:
- What you should know about these tools, and
- What you should be able to do with them.
I will not, however, teach these things. For example, I’ll list the compass operations you should know, but I won’t explain how to perform them. Instead, for this next step, you should find in-depth resources about individual topics, take classes offered by a local outdoor club or retailer, or consider joining me on a guided trip.
When I exclusively used guidebook maps, trail-specific maps, and recreation maps, my map-reading skills struggled. On such maps, it’s often difficult to identify anything but the most obvious and broad features, due to small map scales, large contour intervals, limited color palettes, and the overlaying of copious information at the cost of clarity (e.g. topographic detail obscured by boundary shading or place names). Moreover, these maps are often presented as narrow strips, lacking topographic information beyond the immediate trail corridor.
These maps were sufficient for following obvious trails but not for traveling off-trail, on poorly maintained trails, or in early-season conditions when the trails were snow-covered. In retrospect, I should have taken detailed maps on low-risk outings in order to improve my map-reading skills for when I really needed them.
What should you be able to discern from a map? Ideally, you want it to come alive — you want to be able to virtually see, hear, touch, taste, and smell the area it depicts. But for starters, you should know:
Scale. What is a map’s scale, and how does it correspond to real distances (e.g. inches on the map per mile)? Can you measure distances on the map? Can you envision the size of a topographical feature in the field after seeing it on a map, or on the map after seeing it in the field?
Contour lines. What are contour lines? Using them, can you quickly identify peaks, ridgelines, valleys, mesas and other features? Can you tell whether adjacent lines represent increasing or decreasing elevation?
Relationship of scale and contours. If you use the same map series frequently (e.g. USGS 7.5-minute maps printed at 1:24,000 with 40-foot contours), you will learn the relationship of scale and contours, which is useful in, say, determining the best approach to a trailless summit, the feasibility of a mountain pass, the steepness of a slope, or prospective locations for good campsites.
Background coloring. In general, what do the background colors of green, blue, and white represent? And how are these colors interpreted for a specific location? For example, in New Hampshire, what colors are used to depict natural ponds, beaver ponds, open swamps, and forested swamps? In Colorado, how would you explain white background near the top of an 11,000-foot ridge, immediately below very tight contour lines at 10,000 feet, and in the bottom of a wide valley at 9,000 feet?
Legend symbols. Can you correctly interpret symbols and colors on the map? For example, how does a map depict seasonal water sources, springs, marshy areas, man made structures, land management boundaries, prospects, sinkholes, jeep roads, and more?
The compass is an extraordinarily powerful tool. In areas with limited visibility and subtle terrain, it’s a lifeline. But even in open landscapes with distinct features, I still use it often to confirm beyond a reasonable doubt what I’d deduced already through my map-reading, especially in those occasional situations when conditions are not as favorable.
There are only five operations I regularly perform with my compass:
- Orient a map
- Take a bearing in the field
- Take a bearing on a map
- Apply a bearing in the field
- Apply a bearing on a map
You might notice that triangulation did not make my list. To me, this seems like a useful technique only after I get lost, and frankly I find it easier to simply stay found.
When orienting a map, and taking and applying bearings in the field, your accuracy may be notably affected by magnetic declination. You should have a conceptual understanding of declination and know how to account for it when using a non-adjustable compass or adjustable compass (my preference).
A watch can be useful in structuring the day — wake-up, rests, camps — but in specific regards to navigation it’s essential for dead-reckoning, which for hikers who stick to trails is perhaps the most useful skill to learn. It’s easy, too, since it involves only three variables:
- Distance between two points
- Rate (hiking speed)
Since Distance = Rate * Time, you only need to know two in order to determine the third.
Find Distance in a guidebook or databook, or by measuring it on a topographic map. Observe Time on your watch. And know your Rate by analyzing your performance on past trips, always in consideration of altitude, vertical gain/loss, pack weight, group size, terrain, and your current fitness.
An altimeter watch calculates altitude by measuring barometric pressure, which changes with elevation and also with weather patterns (i.e. low and high pressure fronts). Changes in barometric pressure due to weather will affect the accuracy of an altimeter, and so you must know how to recalibrate it. You’ll need a map featuring landmarks with known elevations, and — for at least the first time you do it — the owners manual.
Once your altimeter is calibrated, it has three uses:
1. Contour. Avoid elevation gain or loss while still covering horizontal distance.
2. Pinpoint your location. If you match your altimeter reading with the same elevation on your map, you know you must be somewhere along that contour. If there is a second known feature, too (e.g. creek, switchback), you are at the intersection of that elevation and that landmark.
3. Hike to an elevation. If you know the elevation of a point of interest (e.g. pass, trail junction) you can stop asking, “Are we there yet?” until you have reached that elevation.
While I strongly prefer a map and compass over a handheld GPS unit, it has its place — like an off-trail route through a featureless landscape with bad visability (think Antarctica, not the AT). If you use one, you should know its four main functions:
1. Pinpoint your location. A GPS will give you the coordinates of your exact location. If the GPS is not equipped with quality maps (unlikely), you’ll need to transfer these coordinates to your paper map, which involves knowing coordinate systems and knowing how to play Battleship.
2. Create a waypoint. Before or during your trip, save the exact locations of important or interesting landmarks — the trailhead, a trail junction, a superb fishing spot, your campsites — as waypoints.
3. Navigate point-to-point. The GPS will tell you the distance and direction to saved waypoints. If you instruct it to navigate to a waypoint, it will take you on a straight-line path there. Note, however, that it doesn’t do the walking for you, and it doesn’t have the intelligence to avoid an utterly stupid route between points.
4. Create a track log. A GPS can drop “bread crumbs” along your route, so that you can follow it back to your car, repeat it on a future trip, and share it with friends.
This has been a long post with a lot of information. Do you feel I should have added anything more about the understanding the uses of navigational tools?
Also, I’m curious to know from readers: What is your level of proficiency? Are there tools with which you are relatively strong or weak?