Map, Compass & GPS

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

Friday, January 3, 2014

Is Your Compass or GPS Receiver Broken?



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.

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