Navigation

[norseman]

 

[wiiawiwb]

Very good learning tool but I disagree with his approach toward declination. "East is least and west is best" sounds simple but it adds an element of work in the field that, in my opinion, is totally unnecessary. Moreover, if a person is trouble, because they are injured or suffering from hypothermia, and not thinking correctly, they may add the declination rather than subtract it. Now, they will be far off course and that error may needlessly cost them their life. 

 

I always draw declination lines on my map in the confort of my home and before I ever go into the woods. That way, I can take readings on the fly without ever having to orient the map. The declination lines drawn in advance cure that problem. A few other issues can rear their ugly head in the field that cause taking a reading a challenge. How do you easily orient the map so when there is a torrential downpour? When you took a reading, were you sure there wasn't metallic substance in a rock just below the surface you laid the map that could affect the magnetic needle? With my approach, I can lay the map on an electromagnet and it doesn't matter. I'm no longer using the magnetic needle to take a reading. 

 

My approach allows you to take a reading the fly, in rain or snow. It doesn't matter, it is quick, and there is no stopping to orient the map.

 

Here is the best information I've ever found that talks about navigation skills and terrain association and it demonstrates the map-marking technique I mentioned above:

 

https://www.adkhighpeaksfoundation.org/adkhpf/navagation.php

 

Here are two video that show the technique of drawing magnetic north lines on a map. The bottom one discsusses declination at length if you are so inclined:

 

https://www.youtube.com/watch?v=kpXibF_yK2c

 

https://www.youtube.com/watch?v=peu7uMp0cVU

 

Edited because I wanted to link a 2nd video by the same individual

Edited October 29, 2025 by wiiawiwb

[norseman]

On 10/29/2025 at 8:11 AM, wiiawiwb said:

Very good learning tool but I disagree with his approach toward declination. "East is least and west is best" sounds simple but it adds an element of work in the field that, in my opinion, is totally unnecessary. Moreover, if a person is trouble, because they are injured or suffering from hypothermia, and not thinking correctly, they may add the declination rather than subtract it. Now, they will be far off course and that error may needlessly cost them their life. 

 

I always draw declination lines on my map in the confort of my home and before I ever go into the woods. That way, I can take readings on the fly without ever having to orient the map. The declination lines drawn in advance cure that problem. A few other issues can rear their ugly head in the field that cause taking a reading a challenge. How do you easily orient the map so when there is a torrential downpour? When you took a reading, were you sure there wasn't metallic substance in a rock just below the surface you laid the map that could affect the magnetic needle? With my approach, I can lay the map on an electromagnet and it doesn't matter. I'm no longer using the magnetic needle to take a reading. 

 

My approach allows you to take a reading the fly, in rain or snow. It doesn't matter, it is quick, and there is no stopping to orient the map.

 

Here is the best information I've ever found that talks about navigation skills and terrain association and it demonstrates the map-marking technique I mentioned above:

 

https://www.adkhighpeaksfoundation.org/adkhpf/navagation.php

 

Here are two video that show the technique of drawing magnetic north lines on a map. The bottom one discsusses declination at length if you are so inclined:

 

https://www.youtube.com/watch?v=kpXibF_yK2c

 

https://www.youtube.com/watch?v=peu7uMp0cVU

 

Edited because I wanted to link a 2nd video by the same individual

I am a very visual person. So I always imagine magnetic north over by Greenland.
 

All my USGS maps have declination at the bottom. But I will check out the video. Thanks!

[wiiawiwb]

There is declination marker at the bottom of topo maps. The problem with that is it is very small and when taking a reading in bad weather you can easily be off by a few degrees. Over 500' it wouldn't matter much but over a mile it could mean life or death. It is always much easier to spread a map out in the warmth and comfort of home and draw the magnetic lines. 

 

You can also do it on the computer with mapping software and and then zero im on the particular area you are going. That way, the parallel lines are printed on the map itself. 

[norseman]

On 3/25/2026 at 3:25 AM, wiiawiwb said:

There is declination marker at the bottom of topo maps. The problem with that is it is very small and when taking a reading in bad weather you can easily be off by a few degrees. Over 500' it wouldn't matter much but over a mile it could mean life or death. It is always much easier to spread a map out in the warmth and comfort of home and draw the magnetic lines. 

 

You can also do it on the computer with mapping software and and then zero im on the particular area you are going. That way, the parallel lines are printed on the map itself. 

Which program do you use?

[cmknight]

Buy a compass that has an adjustable declination indicator. I use my Silva Ranger that I kept from the army. It is also graduated in mils, as oppossed to degrees. The NCEI Geomagnetic Calculator (https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml ) can calculate your declination. Adjust the declination indicator on your compass. As long as you orient your map to north when taking your bearing, you're good to go. The declination itself will not noticeably change for a couple hundred miles (kms) in any direction, so the chances of you accidently walkiing off a cliff are slim ... unless you're in the habit of hiking with your eyes closed.

[wiiawiwb]

On 4/13/2026 at 6:14 PM, norseman said:

Which program do you use?

 

I use a variety of mapping softwares with Cal Topo being my favorite. There is a feature in Cal Topo that allows you to draw bearing lines on the map. You can also print any map to a PDF, using whichever mapping software you prefer, then draw parallel lines on that PDF using a protractor if you have Adobe Acrobat or similar software.  Then you can print copies from there. I'll do that when I go out with several friends so each of us has the same map with identical magnetic-north lines on it.

 

For fun, I enjoy using just a topo map and terrain association to guide me to my destination. I'm typically under the canopy of trees so you can't see peaks, saddles, or other easily-identifiable terrain features. You have to rely on more subtle items to guide you. Very difficult at first but easy to pick up with practice.  

 

When I plan to go to a new location, I carefully study the topo map in advance and try to visualize the hike in 3D before I set foot at the trailhead. That way, you use your mind's eye to help guide you. It is particularly helpful when you're bushwhacking as you will instinctly know if you're not on course based on what you are seeing, or not seeing, as the case may be.