9 comments on “REPOST: Essential Skills: Impact of Magnetic Declination on Accuracy

  1. Since I’m the one who made the backcountry hunting reference in the comments on the last post-
    I was pointing out the difference in the way we use a too map.
    I can still find an exact point on a map,such as a parking lot for a trail head,the convergence of two trails,etc. It’s not using a compass as backup-when you get far enough back in some wilderness areas,there are roadless drainages that have no forest service roads,no old logging roads-nothing,no easy to find landmarks.
    When in those areas,if you want to make it back to camp-you better have figured declination-or you ain’t gonna end up back in camp-you’re gonna end up being lost.
    You still have to figure and shoot an azimuth,and a figure reverse azimuth,and figure declination-or as you pointed out-you end up far from your objective.

    It’s not just this…

    “Now, I’m sure that guys and gals out there who’ve been hunting in one area or another (no matter how large) all their lives and have well used topographical 7.5 minute maps can get from point A to point B and so on with a cursory look at their map and shooting a general bearing with their compass. The primary tool they use is familiarity with the AO (a good thing) and terrain association with the compass used as a back up.”

    Yes,terrain association plays a part-a large part,as we do not use grid coordinates,but we can get to any point on a map by correctly using a compass,with declination accounted for.
    It’s just that the points we get to are generally some type of terrain feature being x distance in y direction from the camp,etc.

    I believe I posted in comments before that when I was working for an outfitter in Montana, we helped the Sheriff and USFS rangers find lost elk hunters often.
    One drainage looks like the next when there are no trails or roads to figure out if you are where you think you are. The guys who got lost either depended on GPS-(doesn’t work everywhere in the northern Rockies-or didn’t back then.)-didn’t have a compass-or had a compass and didn’t figure declination.

    As I said in my comment on the declination post-I will be taking a land nav class next year,to be sure I know how to use grid coordinates to navigate,as opposed to “the elk are hanging out at a certain elevation,and finding a likely looking place on a map to hike to.”

  2. Actually, I saw a series of comments minimizing the need to know what Magnetic Declination can do when one is navigating. While it’s obvious you have quite a bit of navigating experience, some folks seem to conflate learning a Silva type compass with a 7.5 minute map as ‘good enough’ to navigate when the stakes are a lot higher. That’s what this post was addressing: Showing the level of error by not accounting for declination when plotting an azimuth (bearing) on a map and then dialing it in on your compass (unless you’ve already dialed it in because the compass has an adjustable declination feature, like the Suunto MC2).

    My statement about people knowing how to navigate was not a personal shot at you; I acknowledged that some folks (like you) are very well versed in what they do. Unfortunately, the great majority of ‘noobs’ who might read a post and subsequent comments might be tempted to take the advice offered by more than just you, on how unimportant the local declination can be when doing land nav (’15 degrees isn’t really a big deal’ (paraphrasing)), and then we’re going to need a lot of people like yourself to go rescue them. And that’s without S hitting TF. Glad to know you’re going to attend a course to learn how grid coordinates can make your navigation a lot more effective, especially when you have to rely solely on the information on your map to get to one place or another in an area you’re not familiar with….ask me know I know. 🙂 An aside, I lived and navigated in the mountains of Idaho for some years, and knowing the declination was essential when I was in the thick of it off the road on foot in order to plot my way out of wherever it was (typically up in the Clearwater drainage), so I can understand what you mean. Then again, I wouldn’t go into the mountains without a MGRS map or at least a 7.5 minute map that I put grid lines on with an appropriately scaled protractor.

  3. I don’t think you paraphrased,I believe the one comment was 15 degrees isn’t that big of a deal.
    You did a great job of showing exactly why it’s such a big deal.
    Obviously you and I have been in similar backcountry areas,we just navigate a but differently.
    I’ve seen some guys show up for elk hunts without a map or a compass-outfitters don’t provide babysitting services-we were just paid to get the guys to where the elk were hanging out-or bighorns in some cases.
    I agree-learn all you can about land nav-and if you’re- (me) – not using what everyone else is using-learn it-so everyone does the same thing to get to a point on the map.

  4. It’s funny you use the word declination and I learned to navigate using the word variation. Same thing different training. (my training was in the Navy navigating at sea). I am glad you use local declination and those navigating also have to realize that while declination is pretty set based on your location is can also vary widely from what is published to what is actually experienced due to anomalies caused by buildings and buried iron deposits and such. Try orienting your compass in a mobile home. LOL

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