Magnetic Declination

Instructions for land navigators on how to deal with magnetic declination.

Like this video? If so, you'll want to see my online video course in land navigation. It has around four hours of step-by-step instruction to help you find your way over land. We'll start from the very beginning, and go through some pretty sophisticated techniques. To read more about my course, and to link to it, see this page on my web site:

[aarondavis]

Finally explained in a straightforward "visual" way I can understand. Thank you.

[stevegoodrum]

In the UK we are slowly going from west to east magnetic variation !! This makes for interesting conversations between map readers. Your explanation and diagrams were some of the best I've found on you tube.

[huyked]

The illustration really helps me to remember the add and subtract bit. Thanks!

[FloridaAdventuring]

You're welcome. I wanted to make it simple, yet complete. I'm really glad you like it. It's encouraging.

[SeamusOLepreachaun]

Finally a no nonsense plain English video on this subject, thanks buddy!
You have been most helpful.

[hnkabraham]

Nicely explained, I could never remember practical application of thumb rule like "variation east magnetic least" . Your logical expiation did the trick, thanks again. :-)

[Hector-dckm]

I have spent hours trying to compensate for declination. This is by far the most simle way to figure it out.

[curtite]

Thank you. This explains why my compass readings needed the declination "subtracted" from the true north to compare with street map. I was getting the variation mirrored to the wrong side using the compass azimuth. In Connecticut we use 14 degrees west declination on the map. Another satisfied customer!!!

[FloridaAdventuring]

I'm pleased it helps you. That was my purpose. Best regards.

[salmanhyder]

this was really helpful sir, thanks alot for this wonderful elucidation

[TyJee]

Good explanation that is very helpful. Thanks.

The most accurate and easy way I have come up with to remember how to  adjust for magnetic declination is to just look at the declination diagram and to think of the declination diagram as being the hands on a clock.

And for my bearings to be correct, on the map or on the compass,   I have to put the two hands together by moving only one hand or the other. Then asking do I need to rotate the hand CW or CCW to put the two together and which one needs to move?  The True North line or the Magnetic North line.  And them move the compass bezel in that direction by turning it either CW or CCW. The only other thing to remember is that a  map bearing = True North bearing. A compass bearing =  Magnetic North bearing.

For example. If  magnetic declination is 12˚ West . - If I have measured a bearing on the  map  of 60˚ to get the correct compass bearing I have to rotate the True North line CCW to the Magnetic North line to get the two together.  So I rotate the bezel CCW by 12˚ to get 72˚compass magnetic bearing.

 If I have taken a compass bearing of  270˚ to a radio tower. To get the correct bearing to use on the map I would have to rotate the Magnetic North line CW to  the True North line. So I rotate the compass bezel CW 12˚ to 258˚. And that would be the bearing to use on the map because on the map you use True North as the reference North.

If the  magnetic declination is East 10˚. - If I have measured a bearing of 60˚ on the map I would have to move the True North line to the Magnetic North line to get the two hands together to get the correct compass bearing. Which is CW. Therefore I rotate the compass bezel CW by 10˚ to set 50˚ on the compass.

 If I have measured a compass magnetic bearing of 100˚ to a parking lot to get the correct  bearing to use on the map I would have to move the Magnetic North line  to the True North line, which is  CCW. So I rotate the compass bezel CCW by 10˚ to set 110˚ to use on the map.

( Or you could substitute Grid North and GMA  if using the Grid N-S lines instead of True North)

This way of thinking about it has taken primacy over an acronym I created to remember how to adjust for magnetic declination,   which is WAvES. West Add v East Subtract.

Where I only had to remember that WAvES is applied forwardly only when going from Map bearing to Compass bearing. If going form Compass bearing to Map bearing apply WAvES in reverse. That is it becomes West Subtract v East Add.

 But lately I have started  thinking  just looking at the declination diagram as hands on a clock and asking which direction am I going? From Magnetic bearing ( compass)  to True Bearing (map). Or  from True bearing ( map) to Magnetic bearing (compass). And is that direction CW or CCW ( or anti-clockwise as some call it).

[polarbear]

excellent explanation.the best ive seen, cheers

[stevegoodrum]

Excellent explanation with example bearings.

[IsaacC]

Excellent explanation. Thank you for making the video.

[antonyparker]

best video on here explaining this thank you

[geraldya]

this really very helpful and thank you for your explaining Sir!

[FloridaAdventuring]

No. The only time you have to concern yourself with declination is when you're using a map and compass together. If you're not using a map, you can just use the magnetic readings on your compass. If you're not using a compass, but navigating with a map by terrain association, there's no need to think about declination. Hope this helps.

[paganphil]

"From Grid to Mag, add....from Mag to Grid, get rid" (for West declination areas). For East declination areas the formula is reversed.
"Grid" means the bearing on your map and "Mag" means the bearing on your compass.

[FloridaAdventuring]

I'm pleased it was helpful to you. Best regards.

[YST]

Considering the varying declination just within a single state, GPS has a lot going for it.