Taking Good Care of a Compass

A few thoughts on taking care of your compass and what to look for before you go hiking in the backcountry.

Remember that the correct operation of the compass is dependent on the action of the magnetic needle to guide the hunter through the backcountry.  Lots of items in a pack and clothing can effect the needle.  Most understand that ferrous objects such as a rifle barrel, belt buckle, and car keys will deflect the magnetic needle.  Still, take a good look at what is in a day pack.  The batteries from the GPS receiver and a flash light may cause a compass needle to move.

High tension power lines and a vehicle’s electrical system may also cause a magnetic needle to deflect.  Moving a few steps from the vehicle should be sufficient.  One may have to move over one hundred feet from the power lines to avoid deflection.  (GPS Made Easy, Michael Ferguson.)

Some locations will have a high concentration of iron near the surface.  This is known as “local attraction.”  Such concentrations will cause the needle to move too.  Unlike declination, moving away from the immediate area may cause the deflection to stop.  The local Bureau of Land Management or Forest Service Office should be able to identify areas affected by local attraction.

 I recommend that a compass be stored away from electronics (e.g., GPS, radios), batteries and many metallic (knives, saw) objects found in a pack.  I don’t recommend going overboard on this but a compass could simply go in an exterior compartment, a shirt or coat pocket.  Attaching a brake away lanyard to a compass so that is worn around the next is a viable option. This would apply during the off season too; a little separation is a good thing.

It is possible for the magnetic needle to lose its polarity.  This is a function of time and manufacture.  With research, one can learn how to restore the magnetism.  That said, with the modern liquid filled compass this is probably more trouble than it is worth.  Occasionally, check the alignment of the compass.  In the small town where I live, residential streets are aligned true north and south.  Standing on the curb on such a street provides a quick verification of how the compass is working.  To me verification means that the compass direction will mirror that of the street; if the street tracks true north then the adjusted compass should provide a bearing to true north.

At the end of the hiking or hunting season take a look at the compass.  Flush away dirt or sand that may be on the baseplate or sighting mirror.  Look for bubbles that may appear internally and adjacent to the compass needle.  A small bubble may not be something to worry about but a large bubble may impact how the needle swings and moves.  A compass with a large bubble should be permanently removed from the hiker’s kit.

Lastly, keep in mind that a quality compass will retail for $20 or more.  Also, a quality compass can be mechanically adjusted for declination.  Such a compass is a precision piece of equipment.  This is especially true of the Silva Ranger style or the Brunton Eclipse models.  Note that I am prejudice (won’t buy them) towards the cheap stuff found on the racks of the major box sporting goods stores.  If a hunter is willing to spend hundreds of dollars on a rifle scope why not spend a bit more for a decent compass; it can make a huge difference. 

That Old Compass

Grandfather’s compass from decades ago may no longer be the best selection for the hiker.  The image below is of a compass made between 1910-1920.  Though the dial is fairly detailed, the accuracy may be reduced due to the polarity of the magnetic needle. 

 In general terms, the polarity is how the magnetic needle will react to the earth’s magnetic field.  Over a period of almost 100 years, the compass’ magnetic needle may not move in relation to magnetic north as it did when new; that could mean the differences of several degrees.  

To prove this point take a new baseplate compass and compare the two (do not hold them near each other.)  A navigator can also compare it a new compass or a location where a street or trail is known to run true north.

My recommendation then is to leave the old antique compass in a place of honor at home.  It is time to consider buying a new compass.

Magnetic Compass Accuracy

Navigating with a magnetic compass is a skill that takes study and practice.

When plotting the hiker’s position on a map the objective is to have three lines of bearing intersect just like in the image below; this is a position fix.  That is “pin point” accuracy. This is hard to do with a magnetic compass and may not be achievable.

Blake Miller/Outdoor Quest Image
Many factors impact accuracy.  Some the hiker will have no control over.  
These include:

  1. Visual acuity (e.g., how well the hiker can see.)

  2. Polarity of the compass’ magnetic needle – does it point in the right direction? Polarity may change over time such that the magnetic needle may no longer work accurately.

  3. Smooth movement of the magnetic needle.

  4. Alignment of the compass dial to the compass housing.

  5. Local attraction – Similar to declination, local attraction is magnetic interference unique to a specific location.  It may be caused by buried metal objects or an unusually high concentration of iron or nickel in the ground.

  6. Lack of distant objects to sight on.

  7. Weather (e.g., Fog, clouds, and smoke.)
  8. Terrain may hide the objects that the hiker wants to sight with the compass.
The hiker does have control over the following.

  1. Purchasing a quality compass such as the Silva Ranger.

  2. Correctly adjusting for declination.

  3. Staying away from iron and steel objects such as a car, high tension power lines and a hunting rifle.

  4. Practiced sighting techniques.

  5. Practiced with the procedures of plotting the various lines of bearing.

Blake Miller/Outdoor Quest Image
 The image above closely represents what the hiker will have to deal with and accept.  The crossed lines of bearing provide a rough approximation of a position plotted on the map.

Terrain Association will further “dial in” the hiker’s backcountry position.

Blake Miller/Outdoor Quest Image

The image above represents the error of the plotted lines of bearing.  Notice that the lines of bearing have poor angular separation. But by using terrain association the hiker might be able to refine the position fix.  If the hiker is near the river and on the on the river’s east side then the position close the road  will better define location.

Navigation is not hard but it does take practice; it is a perishable skill.

When in the wilderness compare both map and compass with a GPS when possible.  Hiking companions should compare their work too.

Read other compass related posts:

     Buying a Magnetic Compass


A solid reference is June Fleming’s Staying Found and Bjorn Hjellstrom’s Be Expert With Map and Compass.

Nine Navigation Steps to Take at the Trail Head.

The following are nine quick navigation steps to take to ensure one’s navigation kit is set up to best support a hike.

Blake Miller/outdoor quest image
1.     GPS Batteries – load fresh batteries and carry extra for both the GPS and flashlight.

2.     Calibrate the GPS receiver’s compass after every battery change.

3.     Magnetic Compass adjusted for declination – Visit www.magnetic-declination.com for the most current declination value.  Declination changes over time (how old is that map?) and location.

4.     Dump the junk – How many waypoints are stored in the waypoint manager file.  Dump the old waypoints to the absolute minimum; this helps to keep navigation simple.

5.     Match the GPS receiver’s compass to the magnetic compass and the map.   .  Maps are usually set to degrees true.  Have the GPS and Magnetic compass match the topo map.

6.     Erase old track data – clean up the old the track (bread crumb trail) information.  Get rid of 

Blake Miller/outdoor quest image

the clutter.

7.     Remember to stow the maps.  I use maps from www.caltopo.com and will occasionally carry maps from a hiking guides.  Maps are stowed in a zip lock gallon bag or rugged water proof map case.

8.     Mark a waypoint – Give key waypoints a name like “trl hed” or “camp.”  Select waypoint manager to verify that the information has been saved to memory.  If “trl hed” can be viewed on the waypoint manager file or viewed from the map page the hiker is all set.


Blake Miller/outdoor quest image

Orient the map at the trail head.

Everyone in the hiking group should be on the same page in regard to navigation settings.

Using Your Cell Phone In The Backcountry

Last month Jenny Rough wrote an interesting article about why it is a mistake to con you a cell phone when hiking.

She stressed that basic navigation skill “is a use-it-or-lose-skill.  How true.

The thrust of the post is that hikers have an over dependence of electronic navigation while forsaking the rudimentary  principles of using a map and compass. 

Take a look at Jenny’s post.

Visit my other articles on land navigation too:

What Is An Azimuth

An azimuth is the angular direction to an object.  Azimuths are described commonly in degree increments from either true, magnetic or grid north.

In the world of recreational navigation, GPS receiver operations and orienteering the use of the term “bearing” has become synonymous with azimuth.

Azimuth direction is measured from north clockwise in 360° increments. The point from which the azimuth originates is from the center of an imaginary circle.  This imaginary point is the operator.

Azimuth can be measured with a magnetic compass, a map and by rough estimation using the sun and North Star.

Azimuths can be expressed in degrees true and degrees magnetic.  Degrees true uses the north pole as the principle reference while degrees magnetic refers to reference from the magnetic pole.

Outdoor Quest Image
For more information on bearings and azimuth read Making Sense of The Declination Diagram.

Getting Accurate Compass Readings

I found these recommendations a while back when I was researching techniques for using a magnetic compass.  A small error when using a compass can result in a significant error in measurement on the ground.

To obtain accurate readings when using a compass:

  • Ensure the compass has be adjusted for declination. 
  • Hold the compass level and steady so the needle swings freely.
  • Hold the compass about waist high in front of the body, except when using a compass with a sighting mirror or a sighting type compass.
  • Raise and lower eyes when taking a bearing, do not move your head. Always use the same eye when taking bearings.
  • Directly face object that is being measured.
  • Magnetic fields will give incorrect compass readings. Avoid taking readings near magnetic fields such as steel, iron (ferrous metals), vehicles, rebar, and clipboards. Even belt buckles, glasses, and rings can interfere with the compass reading.
  • Take bearing twice. 
  • Adjust for magnetic declination as appropriate.
  • Follow the direction of travel arrow, not the compass needle, when walking a bearing. Always follow the line indicated by the compass rather than relying on judgment as to the direction.
  • Use back bearings to ensure you are on track when navigating.

What do you do when a compass breaks or the GPS just doesn’t seem to be working right?  Here are a few suggestions that will help the navigator.

The theme of this post is to discuss what options the backcountry navigator has with equipment that might not be working correctly. 

When equipment does not appear to provide the correct indication (such as the GPS bearing to the trail head) it’s time to stop.  Never rush navigation.  Stop and take the time to really look over the information provided.  Consult with the rest of the group.

Being able to recognize the proper operation of the hiker’s equipment is important.  This is obtained through field checks well before any trip.  The gas stove can be tested at home before the journey.  The navigation kit can be evaluated throughout the year at the local park or forest. I recommend to the elk and deer hunters in my GPS classes to take their receiver everywhere they go for two weeks prior to leaving for camp.  Push buttons, change displays, mark a waypoint and finally, return to a destination.  Like a pilot of a plane, a map, compass and GPS are the instruments in the backcountry cockpit.

Normally a magnetic compass’ needle rotates freely.  The needle rotates on a jeweled pivot point.  The magnetic compass should be kept level while in use allowing the magnetic needle to move about in the compasses housing.  My Suunto recently just stopped rotating.  I would change direction about 30 degrees and the magnetic needle would move about 15 degrees and then just hang up.

Sadly, there is no simple in the field fix for this.  I gently tapped the compass body and checked the movement of the housing but nothing seemed to work.  Never let broken gear clutter your pack or be used mistakenly.

A back up compass is very helpful in such a situation.  It doesn’t have to be expensive, just reliable.  No matter what you use for a back up, it has to work well and requires testing.  I take all my new compasses to a location in town where the streets run north and south (degrees true.)  I will hike the streets insuring that the compass is on the mark.  This only takes a few minutes.  Recently I noticed that one of my small ball compasses seemed to be at least 20 degrees off; it’s a goner.  Note, that a small back up compass may not be as precise as your primary model.  Also recognize that some compass will only provide a trend of direction such as moving in a northerly direction as opposed to tracking on a direction of 025°.

Before throwing a quality compass out, contact the manufacturer to see what the warrantee offers.

So what does the hiker do if the GPS receiver appears to be broken?   .

The following are steps that I’ll perform:

1.    If I have a GPS with an electronic compass I’ll ensure the compass is activated.  For example on the Garmin 60 series, pressing and holding the “page” button will turn the compass on or off.

2.    I’ll ensure the electronic compass is calibrated.  The compass must be calibrated after each battery change.

3.    Check the charge on the batteries.  If in doubt replace them.

4.    When the “Go To, Find or Where Is” option has been selected, older models will require motion to cause the compass arrow and displays to adjust.  Take five or more steps and see if there are any changes with the display.

5.    Turn the GPS receiver off, open the battery case and remove one battery for about twenty seconds, return the battery and power up the receiver again. 

6.    Once powered up, I want to be certain that the receiver has captured the signals from at least four satellites.

7.    Worse case – call the manufacturer.  Call early in the morning.

In the field, I leave my receiver powered on, collecting data the entire trip.  I keep my receiver in a holster that attaches to one of my shoulder straps.  Before leaving the trail head I “dump the junk” and get rid of old waypoints (e.g., last year’s fishing trip hot spots), I reset data fields on the odometer page and I will clear out my track log.  As I hike, my receiver is collecting all my trail data.  Should my receiver’s compass display fail I can follow my track (the “bread crumb trail” on the map page) back to the trail head.

Lastly, I will consult my map. Using the major land features (e.g., ridge lines, peaks, etc.) I will orient the map, determine my location (using terrain association) and direction of travel.

Sighting With a Magnetic Compass

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.
A compass is an important part of the backcountry navigator’s kit.  The use of Global
Positioning System (GPS) receivers has simplified navigation to an extent but the knowledge of how to use a compass is still important; do not underestimate this skill.  
“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 determine the direction to an object such as a mountain peak.  The 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.)
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 triangulated. 
This article will focus on using a standard baseplate compass such as the two examples pictured below.  (The lensatic and military compass will not be discussed.)
Figure 1 Two examples of good baseplate compasses.
Key features of the two compasses (above) include:
  • They are declination adjustable
  • Liquid filled housing to dampen the magnetic needle’s movement
  • 2° increments on the bearing dial of the compass housing
  • A clear baseplate of adequate size with map scale information and a small magnifier.
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 (engraved in the rotating housing) underneath the red magnetic needle.

  1. In this example, the compass has been adjusted to a bearing of 011° degrees.  The bearing data is found where the direction of travel arrow intersects the compass housing.
At this point the hiker can walk towards the object (e.g., mountain peak, or abuilding) on a bearing of 011°.
If the hiker needs to determine his position, the next step is to triangulate using three bearings.  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° will be used.  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 distinct objects to sight on.  Note that the objects need to be on the topographic map (topo) of the area.  I recommend carrying a forest service map (or something similar) of the area in addition to the topo just incase the objects are too far away.
  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.  See “Orienting a Map” for more information.
  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.
  4. As discussed earlier, 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.
  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.
  7. 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.)  What is even better, with the map oriented to north, as the baseplate is rotated, the red magnetic needle will swing back into position on top of the orienting arrow. 
  8. Draw a line (along the baseplate) from the object to your approximate area.
  1. Repeat the process two more times.

  1. Ideally the three lines will intersect in the immediate area 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.

Defining Compass Bearing and Heading

Bearing and heading are two commonly used terms and two of the most misunderstood.  This post will define and review both terms. 

A dictionary defines the word bearing as:

“….horizontal direction of one point with respect to another or to the compass.”

Simply stated a bearing is the angular direction to an object.  Bearings are described in degree increments from either true or magnetic north.

A compass bearing and heading is measured from north clockwise in 360° increments. The point from which the bearing originates is from the center of an imaginary circle.  This imaginary point is the operator.