9 comments on “REPOST: Essential Skills: Adjusting for Magnetic Declination

  1. Every magnetic compass I ever bought came with a declination map. In most places, the declination is around 15 degrees or much less, so the difference between magnetic and true north is not big enough to worry about.

  2. We would respectfully disagree in that a difference West or East of 15 degrees over most distances would get someone terribly lost, or off target by quite a bit. You’re not going to navigate to a 8 digit grid coordinate without adjusting for declination, and that’s a cold reality. Having one’s azimuth adjusted for the declination increases your chances of getting where you wasn’t to be, especially if you’re looking for a precise location and using the dead reckoning technique. At least, that’s what had been my (and many other much more expert land navigators) experience in the 40 years I’ve been practicing land nav.

    Thanks for stopping by, though.

  3. It all depends how precise you have to be. If you’re calling in artillery, definitely adjust for declination. If you are trying to get out of the big woods and your target is a power line or road, being off 15 degrees will only mean a little extra walking once you have arrived a a terrain or man-made feature where you can dead reckon.

  4. You see, that’s the trick: How high is the navigator’s priority for accuracy. When running a NPT security patrol, navigation accuracy cannot be left to chance; it’s why we plot 8 digit grid coordinates. A little extra walking could cause many significant issues. So, as we focus on using skills for real world preparedness applications, we’ll continue to pound the drum just as many experts do for land navigation precision.

    But feel free to not worry about magnetic declination. Good luck out there.

    Thanks for dropping by.

  5. What may be an issue is the fact that there are a lot of people who can navigate using a topo map and compass.
    What they can not od is navigate to a point on a grid denoted by grid coordinates.
    Many of us learned to use map and compass in Boy Scouts or similar,then learned more as backcountry hunters or hikers.
    Those who have learned to navigate by map and compass for those purposes do just fine because the goal is usually not a precise, exact location-it’s a trail,trailhead,base camp,spike camp,or the next drainage over where the elk are.
    If someone hands me a map,marks a location on it,I can find my way there-what I can not do is show up at a location denoted by grid coordinates-because I never learned to navigate that way.
    Magnetic declination has to be used-you have to account for it-or the farther away your objective-the farther away from it you end up.

    I will be taking a land nav class this year to learn the grid method-because it’s not really the same way of using map and compass as what I’m used to.

  6. Whether or not someone can get in the general vicinity of Point A with a USGS topographical map and a compass (whatever type) isn’t really what the topic is about. Rather, it’s about being accurate on shooting azimuths (bearings) and actually moving along the bearing one believes they are in order to get to whatever point they’re at, because the azimuth determined on the map if used on the compass without declination adjustment is incorrect by whatever declination degree the map indicates. The correct adjustment for magnetic declination affects every single action one might wish to take when navigating. For a moment, let’s presume a person is lost and injured, but has radio contact with a rescue team, and visibility is still good, but it’s getting dark. The injured person could determine their location using a technique called resection (finding an unknown point from two known/unknown points) which involves orienting the map to magnetic north, determining two locations that can be identified by their features on the map, and then shooting an azimuth, converting it to a back azimuth, and then plotting one’s location on the map, converting the magnetic azimuth (bearing) to a grid azimuth (bearing) by the correct application of the declination equation. If the declination is not taken into account, no matter how expert someone is at plotting coordinates, the coordinate will be wrong, and depending on the distance away from the objects used for the azimuth, the degree of error can be very significant, which could mean the difference between being rescued….or not. Add to that natural and man made deviation (magnetic in the compass’s ability to provide a direction, such as iron ore deposits or high tension wires, cell phones, etc), and you can have a very serious problem on your hands. I could go into much more depth, but I’d invite you to attend our land nav course this coming April to get the complete picture.

    As always, thanks for stopping by.

  7. Gentlemen,

    As a pilot and flight instructor declination/magnetic variation is of the utmost importance no matter what the scenario is at the moment. When I teach navigation to my flight students I emphasize the importance of DED RECKONING and Pilotage on a sectional chart of the area incorporating real world pucker factor into the equation. Driving the point home that when they are up there all alone without the safety net of the CFI next to them they have to make it to their destination or they run out of fuel!

    The point of practicing and getting more than proficient in land navigation is essential especially if you have a life/death situation you are dealing with along with the added possibility of wounded team members. Then you had better be on your game in hitting the base camp where your people and your wounded need to be for R&R and medical attention. Bottom line….accept that you don’t know what you don’t know and learn what you need to know to survive. If you know better you can do better!

    By continuing to strive for perfection we achieve an ever increasing level of excellence.

    Semper Vigilans.

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