Map, Compass & GPS

Map, Compass & GPS
Wild flowers along Fall Creek on the way to the Green Lakes - Oregon

Monday, November 27, 2017

Compass Navigation - Using A Compass

 A quality compass is an integral part of the backcountry navigator’s kit.  Sighting with a compass is an important skill that can determine direction to an object or help the hiker locate and identify his position in the backcountry.

This post discusses the steps to be taken to use a compass to plot one’s location on a topographic (topo) map in the back country.  In the vocabulary of navigation this is also known as “fixing” or determining “position.”

The first step is to ensure that the hiker has adequate maps both in quality and quantity.   I recommend carrying a set of maps that include 7.5’ United States Geological Survey (USGS) maps and a second map type such a United States Forest Service map.  The USGS map gives me the detailed information of the immediate area while the other map covers a much broader and larger area. 

Before heading for the trail, take a look at the maps at home.  Scouting from your desk allows you to find significant land features that will surround the direction of travel.  Features such as distinct mountain peaks, a stream, and a ridge line are just of few topographic “hand rails” that can be of value in the field.  By spending some time at home with the map the hiker develops a mental map, a mental picture of the trek in advance of the actual journey. 

Account for declination before leaving the trailhead.  I like to keep my navigation simple and personally use a compass that can be adjusted for declination such as the Brunton 8010G.  Declination information found at the bottom of a topographic map is frequently out of date.  Check the web site  for the current declination.

 “A compass is basically a magnet mounted on a pivot, free to turn in response to the pull of the earth’s magnetic field.  The housing protects the needle and helps you relate the direction in which the needle points to directions on the map and on the land.  A compass by itself can’t tell you where you are or what you are looking at but it can tell you about direction….”

Staying Found, The Complete Map & Compass Handbook, by June Fleming

Sighting with a compass allows the hiker to do several things.

First, sighting on a distant object can provide direction to that object and repeated sightings can provide course corrections along the way.  Secondly, with several sightings on different objects a person’s position can be determined and plotted.

Compass direction to an object is known as the “bearing” or azimuth.   Bearing is the more common term in outdoor recreation and is a term used heavily in GPS navigation.  For example, if a mountain peak is due north of you, the bearing to the peak is 000° (read as zero zero zero degrees.)  A compass can also assist the hiker by orienting a map and following a line of bearing taken from a map.

The picture below offers a quick review of the components of a baseplate compass.

To sight or take a bearing do the following:

  1. Using the owner’s manual, adjust the compass for declination.
  2. While holding the compass at waist level, turn squarely towards a distant object.  Hold the compass so that the direction of travel arrow points directly at the object. (Point the direction of travel arrow away from you, perpendicular to your body.)

  1. While holding the compass, turn the compass housing (the dial) and align the orienting arrow (a red arrow engraved in the rotating housing) underneath the red magnetic needle.

 To determine and plot or “fix” a position, the next step is to plot bearings on the map. In a “nut shell” this means that bearings to three clearly identifiable features are used.  Ideally, objects that have a bearing separation of 30° – 60°.  Good bearing separation provides better fixing information and plots on the map cleanly.  The bearings are then plotted on a map and where the three lines cross is the hiker’s location.  This complete process is called triangulation.

The following are suggestions for triangulating a position in the back country.

  1. Identify three (or more) distinct objects to sight on.  Note that the objects need to be on the topo of the area. 
  2. Orient the topo using the compass.  Orienting the topo means that the map’s left or right border is pointing to true north or 000° degrees true. 
  3. Sight on an object such as a mountain peak or church spire.  (Note that not many objects in the backcountry are so distinct and crisp.  Do the best with what you have.) Ensure the direction of travel arrow is pointed towards the object.  Be as accurate as you can, point directly at the object.
  4. Turn the compass housing until the orienting arrow is directly under red magnetic needle.  Do not move or rotate the compass housing, keep the new bearing in place.
  5. At this point, and while plotting the bearing on the map, the compass will now be used like a protractor.  Importantly, the movement of the magnetic needle is not important.
  6. Lay the compass on the map with either the top left or right corner of the baseplate on the landmark.  This will be a pivot point while aligning the compass.

  1. With the edge of the baseplate in position, rotate the compass (swing) left or right until the N (north) of the compass housing aligns with map North (the top of the map.) 
  2. Draw a line (along the baseplate) from the object (e.g., the mountain peak) to your approximate area.  Draw a nice long line.
  3. Repeat the process two more times using other distant objects to sight on.
  4. Ideally the three lines will intersect in the immediate area; this is the hikers location.  But because of compass error and human error the point of intersection maybe spread out.  Still, triangulation will put you in the ballpark.  Use terrain association to help narrow down your position.


Saturday, November 11, 2017

SPOT Messenger

I always take my SPOT messenger and cell phone with me when I head out to the backcountry; it's part of my ten essentials.

On a recent trip I sent three "I'm OK" status messages.  My first message was sent at 0900,
then 0915 and a third at about 1000.

I always send at least two messages to my family.  I am on the check in list too just to verify my unit is working.

I found that one message was received at  roughly 1020 but nothing else.

When I returned home one message (one of three) was received at 1600.  The last message was received the next afternoon.  This is the first time that I have had such time late message reception.

I called the manufacturer to sort out what happened.

Most importantly learned that the satellite service for SPOT was degraded that day.

I also learned that the internet provider ( was having technical issues receiving and processing SPOT messages.  I then put my .gmail account as an authorized service.

I tested  the messenger from home and received my transmitted data almost immediately.

The manufacturers customer service was excellent.  All my questions were answered. 

For more information and suggestions for using your messenger visit:SPOT Tips

Friday, November 10, 2017


 Many outdoorsmen measure distance in the backcountry by using a Global Positioning System (GPS) receiver.   GPS receivers are reasonably accurate, real time, and provide distance traveled and distance to a destination.
But what does the hiker do if they don’t have a receiver, the GPS fails or batteries die?
A proven method for estimating distance is known as pacing.  Pacing is not as accurate as the GPS receiver, but it can give a reasonable approximation of the distance traveled.  Together with a map and compass, pacing is an important component of evaluating a hiker’s track through the backcountry.  In darkness or periods of low visibility pacing helps to determine the hiker’s location through a process known as dead reckoning. 
Pacing is a method that begins with measuring one’s stride, with the intent of determining an individual’s length of stride. A pace is a measured two steps; a complete stride.  As illustrated below, every time the right foot hits the ground is one pace. Each pace (two steps) normally measures out to almost 50-60 inches.

Perhaps the best method to determine a hiker’s pace is to record it over a specific distance to determine an average.  Before embarking on the trail, the individual should develop a “pace average” over a controlled area first. 
For example, measure the number of paces for a known distance of 100 yards.  To achieve this, go to a high school foot ball field or track.  Walk along a sideline from end zone to end zone.  Count how many paces it takes to go 100 yards.  Do this eight times and record the total number of paces for each 100 yard event.  Determine the average for all eight 100 yard lengths completed.  The result is that the hiker may determine that the average 100 yard pace count to be 58 ½ paces.  (With children compensate and be mindful of their strides being significantly different, including a skip here and an off trail discovery there.)
Whatever the “pace average” may be, do keep the stride natural and smooth.  Don’t try to exaggerate and unnaturally lengthen the stride.
Don’t get too bogged down in the estimation of the accuracy of the average pace. Of larger importance is to understand the complexity of the terrain and how it will impact stride and a hiker’s “pace average”.   Anticipate strides being different.  Take the time beforehand to imitate a 100 yard course on sloping ground.  Further, try a 100 yard pace in soft soil and hard soil, smooth ground and rocky ground. Move to other locations once an average pace is found on a controlled level environment (football field).  Layout a 100 yard course on sloping ground. 
Pacing over long distance can become quite boring and the hiker easily distracted.  This is especially true when the pace count is in the hundreds.  Was that pace 545 or 554?  In such cases pacing beads may be a useful tool.  Pacing beads can be purchased from online venders or made at home using paracord and simple beads. 
A quick Google search will turn up several methods for using pacing beads.  For example, Wikipedia states that “As users walk, they typically slide one bead on the cord for every ten paces taken. On the tenth pace, the user slides a bead in the lower section towards the knot. After the 90th pace, all 9 beads are against the knot. On the 100th pace, all 9 beads in the lower section are returned away from the knot, and a bead from the upper section is slid upwards, away from the knot.”
Pacing beads can be an important asset when Dead Reckoning (known as DR) with a map and compass.  Vigilant compass sighting and a steady “pace average” helps provide a rough approximation of both distance and direction when moving through the backcountry.