Essays

 

Back Country Navigation for the Hunter 
Maps and Coordinate Systems 
Part 1 and 2 
by Dick Blust, Jr., photographs by Mark Furman


Introduction 
The technology available to us today in the form of GPS, combined with tools and resources used for centuries - map and compass - makes back country navigation for the serious hunter more feasible and field-practical than ever before.  

Back country navigation should mean more than being able to find your way back to camp or getting yourself sorted out when you're turned around. Regardless of species, hunting style, topography, or location the hunter can - indeed, should - integrate the aggregate resources of map, compass, and GPS directly into his hunting strategy. With GPS, the right compass, and the right map system, the hunter, trained and practiced in their interwoven use, can roam the back country at will, hitting chosen spots day or night. 

I've trained hundreds of fellow cops, rural firefighters, search and rescue volunteers and hunters in back country navigation, and over the years I've developed a hands-on navigation system for serious hunters that emphasizes practicality and utility above all else, focused on a theme of solving the problems most commonly encountered. 

Many hunters buy a GPS with the notion that it's going to solve all their navigation problems and replace maps and compasses, and it doesn't help that GPS manufacturers don't do much to dispel this notion. This is poor strategy; the fact is that it's far more effective to combine the resources of all three - map, compass, and GPS - in an effective, comprehensive system, the components of which actually serve as backups, each for the other. 

Map, compass, and GPS - we'll deal with them one at a time, covering their interwoven use as we go. I'll be happy to answer any questions through the Kifaru Hunting or Military forum boards. 

Map 
The most important facet of the system - and the least dispensable - is the map, specifically the United States Geological Survey 7 1/2" topographic maps, 1:24,000 scale (1 inch = 24,000 inches, or 2,000 feet), which cover - and are available for - the entire United States outside of Alaska, which is covered by the USGS's 1:63,360 scale (1 inch = 1 mile) topos. (In addition, the USGS also has available the smaller-scale 1:100,000 topos for the lower 48 and the 1:250,000 scale series for Alaska. I like to call maps of this scale "reconnaissance maps." Depending on topography and circumstances, these, too, can be very useful.) 

Grid Systems 
There are two grid systems that can be used with USGS topo maps - Latitude-Longitude (Lat-Lon) and Universal Transverse Mercator (UTM). We'll cover Lat-Long first, as a general familiarity with it is helpful, but as we'll see, the best system for land navigation - especially the for the hunter - is UTM. (Be aware that your GPS can be set for any grid system you like - it takes only a second to change - but it almost certainly came from the factor defaulted to Lat-Lon. We'll discuss changing the setting in the "GPS" section of the essay.) 

Every map grid system basically works the same way; a coordinate is a combination of position along a east-west line and a north-south line. The most basic version is your hometown phone book map - City Hall is at G-5, Smith Park is at B-11, and so forth. 

Lat-Lon is grounded on two sets of imaginary lines, beginning with parallel lines of latitude, which circle the earth from east to west. The Equator is zero degrees latitude, parallel lines of latitude north of the Equator are referred to as parallels of north latitude; those south of it are called parallels of south latitude. 

Imaginary lines of longitude, called meridians, circle the earth from pole to pole, beginning at zero degrees longitude at Greenwich, England running east and west from Greenwich and meeting at the International Date Line on the opposite side of the globe.  

Lat-Lon coordinates are expressed in geometric terms of degrees, minutes, and seconds; each degree is made up of 60 minutes, each minute of 60 seconds, and here's where the trouble starts for the land navigator. Coordinate information here is expressed in mathematical terms, not in units of actual ground distance, and trying to correlate the two is a nightmare. To make matters worse, while latitude is a constant anywhere on the planet - one minute of latitude subtends a nautical mile of 2,000 yards - longitude is not constant; meridians of longitude are constantly converging as you move north or south of the Equator. The bottom-line, real-world headache for the land navigator: Lat-Lon coordinates are more difficult to plot on a map, because they represent a grid system for a sphere (the earth) transferred to a flat surface (the map). That's why 7 1/2" topo maps are rectangles and not squares: the map boundaries on the east and west sides are actual meridians of longitude 7 1/2 minutes apart and the north and south boundaries are parallels of latitude, also 7 1/2 minutes apart. 

Universal Transverse Mercator - UTM - has been dealing with all of Lat-Lon's problems since 1947, when it was adopted by virtually every military ground force in the world. 

First and foremost, UTM beats Lat-Lon's most fundamental shortcoming by taking the spherical shape of the earth out of the formula; it puts a flat grid system on a flat surface. Here's how: picture an orange representing the earth sliced twice, peel-deep only, from pole to pole, with the slices at a ninety-degree angle. Pull one of the peels off and look at it; you're holding a peel that's pointed at both ends and bowed out in the middle. Now place the peel on a table, flatten it out, and then put your map grid on it - that's UTM. 

UTM covers not quite the entire planet - the extremes of both polar regions are left out, but it's OK; a different grid system built into your GPS called UPS covers these areas, in case you draw out on a penguin hunt or a visit to Santa's Castle. The resulting flattened map of the world starts the International Date Line and, moving east, divides the planet into 60 zones of 6 degrees of longitude each. The zones covering the lower 48 states, for instance, are zones 12 through 19, moving west to east. 

Here's where we leave Lat-Lon behind, even as a general reference. Everything from here on out is expressed in actual land measurements under the metric system. It helps here to get a basic handle on two metric measurements: meters and kilometers. A meter is about 39 inches - a little over a yard. Your memory crutch here, when dealing with a distance expressed in meters, is either to add a healthy dab to convert the distance to yards or, alternatively, multiply the distance in meters by 1.1 to obtain a more precise calculation - whichever you find handier. An object 300 meters away then, is "a dab over 300 yards;" if you do the math, about 330 yards. 400 meters is about 440 yards, 600 meters is close to 660 yards, and so on. 

A kilometer - a "click" to those in or who spent time in the military - is 1,000 meters or about 1,100 yards. It's the metric system's rough equivalent, in general terms, of a mile and to convert kilometers to miles, multiply by .6 or 6/10s. 5 kilometers - 5K - is thus about 3 miles, 10 kilometers is about 6 miles, 30 kilometers about 18 miles, and so forth. 

OK, here's how it works in a nutshell: a UTM coordinate is your distance from west to east across your zone in meters - your Easting - and, again in meters, your distance north of the Equator - your Northing. That's it. Period. The key thing to remember about UTM is that it only deals with two directions: west moving east and south moving north: the numbers always get bigger as you go east, and they always get bigger as you go north. Always. Everything, therefore, is east and north, or, if you prefer, right and up. The way UTM breaks down, every square meter has - indeed, is - its own coordinate. 

Let's try an example to illustrate. The summit of Hawks Rest in Wyoming's Yellowstone River country appears on the UTM-gridded map in Figure 1. Its UTM coordinate is expressed - and will appear on your GPS if you're standing on top - as follows: 

12 5 73 548 E

48  83 868 N  

The top number - the Easting, identified by the "E," - is always expressed first, and the first number in the Easting is always the zone number; in this instance, zone 12. The rest of the number tells us that the Easting itself is 573,548 meters across zone 12 from west to east. 

The second, lower number is the Northing, identified by an "N," which identifies the Northing as 4,883,868 meters north of the Equator. Where the Easting and Northing meet on the map is your UTM coordinate. 

Refer now to Figure 2. The map in Figure 2 is identical to Figure 1's map - it's UTM-gridded and "rulered" in 100-meter increments. The Easting figures appear along the top of the map, and the Northings on both sides. As always, let's do the Easting first. 

As indicated, our Easting is 12 5 73 548. Look at the Easting figures along the top of the map and you'll see, from left to right, the Eastings 12 5 72 000, 12 5 73 000, 12 5 74 000, 12 5 75 000 and 12 5 76 000. Because UTM coordinates reflect actual distances in meters, we know that there are 1,000 meters (1 kilometer) between each of these major graduations; that is, 1,000 meters between 72 and 73, between 73 and 74, between 74 and 75, and between 75 and 76. Between each of these major graduations, the map is "rulered" along the edge in 10 increments of 100 meters each. 

To find our Easting of 12 5 73 548, we move along our Eastings on the top of the map to 12 5 73 000, then continue to move east, counting 5 100-meter increments to reach an Easting of 12 5 73 500. We then "eyeball calculate" 48 more meters, continuing our move east roughly halfway to the next 100-meter increment (halfway would be 50) to reach our Easting of 12 5 73 548, as indicated in Figure 2. We now have our Easting; we know that we are somewhere on this south-to-north line, which has been penciled in. 

To complete the process, we now move to our locate our Northing, which is 48 83 868.  

Referring again to Figure 2, look at the Northing figures on the left (or right) side of the map and you'll see, from bottom to top, the Northings 48 83 000, 48 84 000, and 48 85 000. Just as with our Eastings, because UTM coordinates reflect actual distances in meters, we know that there are 1,000 meters (1 kilometer) between each of these major graduations; that is, 1,000 meters between 83 and 84, and between 84 and 85. Between each of these major graduations, the map is "rulered" along the edge in 10 increments of 100 meters each. 

To find our Northing of 48 83 868, we move up our Northings on the side of the map to 48 83 000, then continue to move north, counting 8 100-meter increments to reach a Northing of 48 83 800. We then "eyeball calculate" 68 more meters, continuing our move north roughly a little more than halfway to the next 100-meter increment (halfway would be 50) to reach our Northing of 48 83 868, as indicated in Figure 2. 

With our Easting and Northing in hand, we can now plot the position. A line - which I call a "plotting line" parallel to the Easting grid lines is drawn mentally (or physically, as in Figure 2) running south-north for our Easting, and a second "plotting line" is drawn parallel to the Northing lines for our Northing. The intersection of these lines on the Figure 2 map is our coordinate, 12 5 73 548 E, 48 83 868 N, the summit of Hawks Rest. (Once again, note that you can physically draw in the plotting lines, or "eyeball plot" your position with imaginary lines.) 

Remember - it's important that plotting lines be drawn parallel to the UTM grid lines, not the lines bordering the edge of the map. 

Recalling that the numbers always get bigger going east and north, if you were standing at the coordinate above, then moved 10 meters east and 10 meters north, your new coordinate would be as follows: 

12 05 73 558 E

48  83 878 N  

Let's go now to the UTM-gridded map in Figure 3 for additional examples.

There are 3 UTM coordinates for identifiable landmarks in this exercise, as follows - use the same sequence we just used to find the summit of Hawks Rest and plot them: 

12  7 13 332

    46  81 245   (McKay Lake) 

12  7 12 492

    46  82 075   (Murray Lake) 

12  7 12 367

    46  79 910   (Scotty Lake) 

That's UTM. It's simple, it's practical, and it's easy to work with. Is it important to remember that an Easting represents the distance in meters west to east across your zone, or that the Northing is the distance north of the Equator in meters? Not really. What is important is that this is how your GPS is going to provide you your position, which you can then plot with accuracy on a topographic map. And as we'll explain the "GPS" section of the essay, UTM also works in reverse: you'll be able to plot a UTM coordinate from your topo, tap it into your GPS, and let it and your compass take you there. 

The key here - and you will hear it again - is to practice: the more you use UTM coordinates in practice map plotting, the more readily, quickly, and accurately you'll be able to do it when you really need it. 

Remember: The numbers always get bigger as you go east,

and they always get bigger as you go north. Always.

Everything is east and north, or, if you prefer, right and up. 

Every square meter has - indeed, is - its own coordinate. 

Remember - it's important that plotting lines be drawn parallel to the UTM grid lines, not the lines bordering the edge of the map. 

 

Topographic Maps 
Though in terms of quality there are none better on earth, the "store-bought" USGS topos have their drawbacks. The maps themselves are large and can be difficult to handle in field conditions, especially when you're trying to do grid plots or compass triangulations / resections; there just aren't many good writing/work surfaces available at 9,000 feet. And before you can do any plotting or serious triangulations / resections, you have to grid the maps by hand, using either the Latitude-Longitude (Lat-Lon) or Universal Transverse Mercator (UTM) tick marks [Figures 4 and 5]. ("Store-boughts" are not UTM-gridded and"rulered" like the maps you used in figures 1 through 3; these were generated by a special topographic map program called Terrain Navigator that we'll be discussing soon.)

 

Figure 4 is the northwest corner of the 7 1/2" Dundee Meadows (Wyoming) topo.

As indicated, the northwest corner of the map is a precise Lat-Lon coordinate, 43 degrees, 52 minutes, 30 seconds north latitude, 110 degrees west longitude. Also indicated are several of that particular topo's tick marks; the zone 12 Easting tick marks 5 81 000, 5 82 000, and 5 83 000 can be made out along the top of the map, as can the Northing tick marks 48 57 000 and 48 58 000 along the left-hand edge. One of the corner's Lat-Lon tick marks can also be seen along the top of the map; the tick for the longitude 109 degrees, 57 minutes, 30 seconds, shorthanded to read 57'30". 

These are the marks that are used to hand-grid - using a pencil and straight edge - a standard "store-bought" topographic map. If you're using Lat-Lon, you must connect the Lat-Lon tick marks; if employing UTM, the UTM tick marks must be used to create a grid, as shown in Figure 5. 

Then, with that accomplished, a Lat-Lon scale or ruler or UTM corner scale [Figure 6] is necessary to plot a coordinate, depending on which grid system you're using.

 

(Here the UTM grid/UTM corner scale approach is much the superior of the two; the Lat-Lon/Lat-Lon ruler approach is more complex and vulnerable to mistakes.) Figure 6 features a combination Lat-Lon ruler and scale and UTM scale manufactured by Brunton and the long-standard U.S. military issue map protractor with its UTM corner scales. 

click here to continue to part 2