Built-in Declination adjustment - why wouldn't one use it?

HikingMano

HikingMano

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I recall reading that some folks don't like to use the built-in declination adjustment feature on compasses. Since it seems to be simpler, more accurate, and less time-consuming to utilize than "making your map speak compass," why shouldn't one use it? Is it just because one might forget to adjust for a new declination on an outing in a different area?


Thanks in advance :)
 
Most people don't know how to use a map and compass to begin with.
Some people are highly competent, but learned on a compass without declination(lensatics used by the military don't have it), and are accustomed to adjusting on their own.
I can come up with a lot of reasons you don't always need pinpoint accuracy from your compass, but if I know the declination, and have a compass that adjusts for it, I personally don't have a reason NOT to set it.
 
I personally like declination adjustment but I can see how relying on it could be faulty if you travel a lot. Learning to do without the adjustment might be better than forgetting to set it at your new destination. Interested to see others opinions. OwenM may be on to something with military folks being trained without the adjustment.
 
Ah yes, that's true. I might have just been reading comments by people who learned on a compass without declination, and who don't want to fix what isn't broken :thumbup:
 
It's also been my experience that most of the time the declination adjustment really isn't that necessary anyway. It only really becomes important where the declination is very severe or if you will be trying to travel very long distances along one bearing.

Whether it's right or wrong, I 99.9% of the time use terrain recognition anyway, the compass only comes out on the rare occasion I can't align North just with the map and looking at terrain.
 
Yeah, it's only 14E where I am, and I don't travel long distances or do orienteering activities. So it hasn't mattered that much to me thus far. But I still wanted to know the thought process of those who don't use it, in case I'm missing something.
 
rocketbomb said:
It's also been my experience that most of the time the declination adjustment really isn't that necessary anyway. It only really becomes important where the declination is very severe or if you will be trying to travel very long distances along one bearing.
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+1. I agree with that. I never need to travel that far at one time.
 
I use a small Silva Guide compass, wish had declination adj, but none of the smaller compasses I've looked at have it- soooo..... I do it the old fashion way and just calculate it :) I used the same compass when I worked for the USFS where I had to locate camps on a map (triangulating), got pretty good w/ the math, not using as it nearly as much so the math doesn't come as easy :)
 
I'd like to point out that it's one thing to disregard declination because of short distances, or knowing when to compensate for it by using terrain association, and not having a clue about it. Everyone should know about declination and how to compensate for it... in my opinion, of course.
Depending on how much the declination is in the area that you're in, you'd be surprised on how far off your course you'll get without compensating for it.
 
When using a map and compass together, it would be just plain foolish to ignore declination when outside of your own cornfield. Few of us (note the chart below) live on the Agonic Line where declination is close to zero.

The consequences of ignoring 1 degree declination translates into roughly 88 feet in 1 mile of walking. If one multiplies that 88 feet by the declination in your area, it doesn't take a math genius to realize that you could be entirely lost in short order.

The area that I live in is currently (changes every year, of course) 17 degrees easterly declination. My hunting area is roughly 16 degrees easterly. The hunting camp sits in a heavily wooded wilderness mountain environment where no roads exist, the closest semi-ghost town is 73 miles off, no cell phone service, and below freezing temperatures each and every night. We generally hunt 5 to 6 miles out each day from the camp keeping a close eye on map and compass. Now, imagine being out 6 miles from camp with a declination of 16 degrees and ignoring the math on the way back! Ignoring the declination here will literally put you into the next county without ever seeing camp...if you are lucky enough to survive the ordeal!!

Personally, as an aviator, I have flown FAR too many search and rescue missions looking for folks who didn't or couldn't get their map and compass skills correct. Though I own several wonderful GPS systems (boat, airplane, hand held), they are not an adequate answer to poor navigation skills. Batteries, instruments, electrical systems can and do fail on occasion.

If you have a compass with a declination adjustment screw, SET THE THING!! That is why it is there! If you don't, KNOW WHEN TO add and subtract your declination! If you don't have any, or little compass skills, take a land navigation class (I teach one) or, join an orienteering club. I learned the basics with the Boy Scouts back in the early 60's when Boy Scouts were expected to know this stuff.

Know where you are and stay safe. :)


AgonicLineA1.gif
 
Declination?
A lot of folk do not know what it is
And not understand what errors not using it creates

The consequences of ignoring 1 degree declination translates into roughly 88 feet in 1 mile of walking. If one multiplies that 88 feet by the declination in your area, it doesn't take a math genius to realize that you could be entirely lost in short order.
Click to expand...

Take two bearing of landmark mountains at 10 miles distance
Put those back on your map with out declination adjustment
You are now lost!

Those that do it in their head, and not adjust theri compass are better than I am.

When I need to take three bearing for find out where I am, I do not want to make more calculations with subtracting or adding
 
Thank you Dannyboy (and everyone else), all sound advice. I don't think any of us actually ignore it, but as pointed out, if you're in a familiar area, going short distances in relatively open country where you can readily recognize terrain features, or following a trail...then it takes a back seat or serves to confirm location when needed. I personally DO use my declination adjustment, even though I don't yet do a lot of off-the-beaten-path stuff. Why be inaccurate when you can be accurate for not much added effort. But I do want to start doing longer trips and off-trail exploration in forested areas, so I'm working on my map and compass skills (I don't even own a GPS). Because of that, I started this thread looking for an answer to the original question:

HikingMano said:
I recall reading that some folks don't like to use the built-in declination adjustment feature on compasses. Since it seems to be simpler, more accurate, and less time-consuming to utilize than "making your map speak compass," why shouldn't one use it? Is it just because one might forget to adjust for a new declination on an outing in a different area?
Click to expand...

I don't routinely do stuff in areas that are far apart enough for my declination to vary more than a few seconds. That's why I wanted to make sure there's nothing else I'm missing in using my built-in declination adjustment instead of drawing out MN lines on my maps.
 
I remember "East is least, west is best". Why? When I learned, we had basic baseplate compasses with no declination adjustment. Then, in the military, it was the lensatic compass with no declination adjustment. If you have an up to dat emap, it should have the declination on it, then you can add or subtract.

Thing is, declination adjustments are fine, but can also cause problems if you get complacent. If going long distances (I don't mean 10 or 20 miles here), you may have to adjust your declination several times, or if you are working with an old map, if you set your declination adjustment to that, you'll be off course.

Having to adding your head gets you used to looking it up.

If you have a declination adjustment, I'd add a line to your pre-trip checklist to look up and adjust for your current declination value.
 
I'm guessing most folks don't bother with declination because it doesn't come into play if you're using the compass to navigate from feature to feature over terrain, or for example to take bearings on two landmarks to relocate a spot, such as a good fishing hole on a lake, or taking a safety bearing when entering the woods. Declination definitely matters when using a compass in conjunction with a map. Ten degrees of deviation over the course of a mile will result in over 300 yards of error. If I'm using a compass for map work and it doesn't have an adjustment for declination, I use the declination scale on the map as a guide to draw declination lines on my map. It is then a simple matter to align the map properly to magnetic north.
 
Most map declinations are so outdated they are completely useless. Go to the USGS website and check out their declination calculator, works like magic.

I'm floored by some of the comments on this post! Its tough enough with declination adjustment using a baseplate compass. Most of the baseplate compasses have a 1-2 degree accuracy (when used properly). Right off the bat you can be way off even if you know what you're doing!

If you want better accuracy, then get a lensatic or sighting compass and know how to adjust for declination. That will give you the best accuracy.

If you are going relatively short distances between bearings, then hit a baseplate with the declination adjustment. Its way easier and gives you great piece of mind when you don't have to worry about the declination.
 
The declination where I roam is less than 2 degrees. For short woods romps, it just doesn't matter.
 
My Silva has dec. adj. feature, and when using that compass, I set it. I also have a lensatic style compass that doesn't, and when using that, I adjust the old fashioned way.
 
pvicenzi said:
The declination where I roam is less than 2 degrees. For short woods romps, it just doesn't matter.
Click to expand...

What? With a typical baseplate compass you could be off by about a 1/2 mile after travelling only 5 miles! IMO Declination always matters. Know how to use a map and compass, if somebody doesn't know how to adjust for declination then get a compass with declination adjustment.
 
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Dannyboy Leather said:
I learned the basics with the Boy Scouts back in the early 60's when Boy Scouts were expected to know this stuff.
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Would you believe when I was in Scouts they didn't even teach us about declination? It was in the handbook but nobody had to learn it. I don't even think it was even mentioned in the next handbook edition! When I worked as a Scouting Professional we tought how to do an orienteering course only. No real field work. Nowadays most Scouts look at you like deer in a headlight if you mention declination!
 
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