Fundamentals of Navigation for Adventure RacingUsing the Compass
Using the Compass
Using the compass is probably the easiest part of navigation. The compass contains
three basic parts that you'll use in adventure racing:
The needle is the red arrow and it points north... unless you accidentally leave it on a speaker or some other magnet for a long time. The base is the clear plastic piece that you hold. The bezel is the rotating circle that goes around the needle. What does knowing where north is do for you? Well, it helps you orient yourself and the map. When reading the map, I typically find north on the compass and then turn my body that way. Then, I put the map in front of me with north point forward (the part that's not against my body). This way, when I look at the map and match up what I see on the map with the real-world, everything is oriented correctly. For example, east on the map is to the right and east in the real-world is to the right. Let's say your map shows a road that runs east and west and you want to go west. The first thing you should do is find north on your compass. Now turn your body to face north. At this point, you'll be standing on the road and it will run to your left and right. You know that west is to your left, so you can turn to your left and start walking.
A good way to test to see if you are actually headed the right way is to turn the bezel on your
compass to where the direction you want to be heading marking (west in this case) on the bezel
is at the front of your compass. At this point, the needle of your compass should be in the "shed".
This is called "putting red in the shed" and indicates that
you are facing matches the direction marked at the front of your bezel. The picture below shows an
example of putting red in the shed to head west.
This picture below shows an example of "red not in the shed". In this picture, west is at the front
of the bezel and the needle is facing 180° in the opposite direction. This would mean that you are
actually facing east when you meant to be facing west.
Taking a bearingThe example above showed you how to dial-in the bezel on your compass to face a specific direction. This is a form of doing what we call "taking a bearing". To take a bearing, you simply determine which direction you want to head and dial that in on the bezel. Then you turn your body until the red needle ends up in the "shed" in bezel housing.
How do you determine which direction you want to head? Well, this is based on the map and your goals.
Take a look at the map below. There are two CPs on the map. Let's say you are at CP1 and you want to
go to CP2. In this example it's easy to tell that you need to go directly south to reach CP2.
So, you would dial-in south on your compass bezel and turn your body until the red is the shed.
Then you would start walking forward. Keep your eye on the compass needle as you walk. If you
veer off your course to the left or the right, the needle will drift out of the shed.
This means that you are off-course and need to correct your path to get back on course.
Sometimes the bearing you want to head isn't directly west or south. Instead, it's somewhere
in between one of the cardinal points on the compass. We can determine exactly the direction by
using the little numbers on the bezel. The bezel is a circle and divided into equal lines to
complete the entire 360° range. East is the same as 90° on the bezel. South is 180°. West is 270°.
North is 0°. You might need to head somewhere between east (90°) and south (180°), so you'll
have to calculate exactly what that bearing is. Have a look at the map below. You are at CP3
and want to go to CP4.
To calculate the bearing, put your compass on the map. Place the back edge of the compass where you
currently are (CP3). Turn the compass such that the front edge of the compass is pointing to
where you want to go (CP4). See the picture below for an example of aligning the compass from CP3 to CP4.
It's marked as a red line along the edge of the compass.
Now, you turn the bezel on the compass until the lines in the bezel housing line up with the
north-south grid lines on the map. This is marked in red in the picture below.
North on the bezel should be facing north on the map. This is marked in purple in the picture below.
The number at the marker at the top of the bezel is the bearing you want to travel. This is marked in
blue in the picture below. In this case, the bearing is 30°. To travel this bearing, you will turn your body until the red needle is in the shed and start walking in that direction.
Declination
Wouldn't it be nice if everything were that easy? That north was always in the same spot and no
matter where you were on the planet your compass would point to the same north? Well, it's
not a perfect world. The curvature of the Earth and lots of other things that only a person
with a PhD in geophysics can completely understand causes our compasses to be off of true
north by some percentage the further east and west of the Mississippi River (approximately)
you go. On your map, you will see some text that tells you what the declination amount actually is.
This is usually located at the bottom right-corner of the map and it looks like what you see in the
picture to the right.
This particular map is from a location in Texas, which is west of the Mississippi River and the declination is 6°. This means that your compass will be pointing 6° too far to the east. In this case, we say that the declination is 6° east. We can adjust for this problem in two ways:
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