Know Your Magnetic Declination

[Eyebone]

I was talking to a guy at work last week who professes to be an avid hiker.

I asked him if he had a compass, he said "yes" but couldn't tell me what sort.

Then I discovered he did not know the declination for this area.

Well the magnetic declination for Seattle is 18.3 degrees west.

Here is a web site that lists MD for all cities across the continental United States.

http://www.dvbresource.com/charts/ci...eattle-WA.html

[trainedtosave]

Mine is Nashville TN, 5 degrees, close enough to 0 to be fine.

Compasses are important, but the first thing I learned in outdoors skills was firestarting, then shelterbuilding, edible plants, ect. I saved orienteering for last. Not that it is not important, but following a compass isn't hard, and the others take precedence in a true survival situation.

[Eyebone]

Yeah, I believe it's called a "skill set".

[Mr Bobo]

I was working on a boat one time and the gyro-compass broke. After a few weeks of using the binnacle compass (which has magnets to compensate for the deviation caused by the metal hull) somebody managed to break that too. So the captain decided that rather than fixing either of the reliable compasses he would just put a random compass from his cabin in front of the helm. He also came up with the brilliant idea of securing it there with metal brackets. So for about 4 months we had to steer by a compass that had a deviation of about 50 degrees. Whenever we had to change course we had to wait a few minutes and look at the GPS to see if we were going in the right direction.

[Discordish]

I hate to admit this

but I still dont know how to use a compass aside from knowing where N,E,S,W are

[vicdotcom]

Originally Posted by Eyebone

Then I discovered he did not know the declination for this area.

Well the magnetic declination for Seattle is 18.3 degrees west.

Here is a web site that lists MD for all cities across the continental United States.

http://www.dvbresource.com/charts/ci...eattle-WA.html

Remeber also that Declinaion of an area changes over time. Seattle can be 18.3 west now, but in 5 years you could be at 19 or more.

The magnetic north pole of the earth is constantly moving and drifting. That is why the declination changes and why you shouldnt use a 10 year old map when doing detailed orienteering.

[Eyebone]

Originally Posted by vicdotcom

Remeber also that Declinaion of an area changes over time. Seattle can be 18.3 west now, but in 5 years you could be at 19 or more.

The magnetic north pole of the earth is constantly moving and drifting. That is why the declination changes and why you shouldnt use a 10 year old map when doing detailed orienteering.

This is exactly why the web site is posted here, this is current information.

If one does not appreciate the value of a compass or plotting an accurate course and determining a current position, S'okay.

[Maurepas]

Also good:

http://www.ngdc.noaa.gov/geomagmodels/Declination.jsp

Can search for your declination via zip code or coordinates. Always up to date.

And here:
http://www.magnetic-declination.com/

Searches off your I.P. address.

[sojurn87]

Originally Posted by trainedtosave

Mine is Nashville TN, 5 degrees, close enough to 0 to be fine.

Compasses are important, but the first thing I learned in outdoors skills was firestarting, then shelterbuilding, edible plants, ect. I saved orienteering for last. Not that it is not important, but following a compass isn't hard, and the others take precedence in a true survival situation.

I get what you're saying, but one could also argue hypothetically one may not need to build a fire, shelter and search for food in the first place if they knew how to read a compass

[Creek Walker]

I can see where knowing your magnetic declination would be helpful, but that is mainly for pilots and ship captains is it not? Educate me if you think I have a screw loose.

Here in southeastern Illinois a compass is more or less a toy as most roads are laid out in sections or 660 acres which is 1 square mile. So theoretically you can drop me off anywhere and I will find my why home even from the river bottoms. I don't need a compass to tell me which way north is even if its pitch black and I don't have any light. It's a simple matter to look at or feel a large bark tree such as a Maple and you will know which way is north. The bark on the north of the tree is tighter then the bark on the south face of the tree. Hasn't failed me yet.
Another thing is the prevailing winds, them in themselves are not reliable but once again older trees tend to lean away from the prevailing winds in my case its usually east. Plants, all sunflowers point east towards the rising sun.

I had a bad experience with a compass while mule deer hunting in Idaho. I shot my azimuth going in and made note of landmarks. Well on my way out I realized my compass was always pointing to my rifle barrel. So it was the landmarks that I had noted that led me back to my truck.

[vicdotcom]

Originally Posted by Creek Walker

I can see where knowing your magnetic declination would be helpful, but that is mainly for pilots and ship captains is it not? Educate me if you think I have a screw loose.

...I had a bad experience with a compass while mule deer hunting in Idaho. I shot my azimuth going in and made note of landmarks. Well on my way out I realized my compass was always pointing to my rifle barrel. So it was the landmarks that I had noted that led me back to my truck.

First I have to say that the last part of you post was simply great (the part about the rifle)! Thanks for sharing!

But you are right in some ways and leaving out some situations in others. For instance, if you are in a known territory and know your way arround it well, you probably dont need to have a detailed compass reading. Landmarks are great also to use.

The map and compass come in handy the most when you are in an area that you are not familiar with. It may not even be an area that has a lot of landmarks like FL or AZ. The compass will help you plot a course and stay on course when hiking in unknown areas. But also if you dont have a map of the area, a compass wont be much more use either besides N S E and W.

[Cowboy832]

Originally Posted by Creek Walker

I can see where knowing your magnetic declination would be helpful, but that is mainly for pilots and ship captains is it not? Educate me if you think I have a screw loose.

Here in southeastern Illinois a compass is more or less a toy as most roads are laid out in sections or 660 acres which is 1 square mile. So theoretically you can drop me off anywhere and I will find my why home even from the river bottoms. I don't need a compass to tell me which way north is even if its pitch black and I don't have any light. It's a simple matter to look at or feel a large bark tree such as a Maple and you will know which way is north. The bark on the north of the tree is tighter then the bark on the south face of the tree. Hasn't failed me yet.
Another thing is the prevailing winds, them in themselves are not reliable but once again older trees tend to lean away from the prevailing winds in my case its usually east. Plants, all sunflowers point east towards the rising sun.

I had a bad experience with a compass while mule deer hunting in Idaho. I shot my azimuth going in and made note of landmarks. Well on my way out I realized my compass was always pointing to my rifle barrel. So it was the landmarks that I had noted that led me back to my truck.

It depends on what you are doing. If you are venturing into the woods a short ways, or are very familiar with the area you are in, knowing your declination angle(along with all the other land nav skills) is not that important. However, if you are attempting long range, precision land navigation, it is a must. Depending on where you are at, the difference between magnetic north and grid north could be substantial, and WILL be the difference between hitting your mark, and being possibly thousands of meters away from where you wanted to be.

There are a lot of skills associated with land navigation besides knowing your declination angle: Pace count, plotting a course, knowing how to perform intersection, and resection, how to properly shoot an azimuth/back azimuth, and sadly, knowing how to properly read a map.

[bikerdruid]

here is the government of canada site for calculating magnetic declination.
it takes input for latitude and longitude.
http://geomag.nrcan.gc.ca/apps/mdcal-eng.php

[Creek Walker]

Originally Posted by Cowboy832

It depends on what you are doing. If you are venturing into the woods a short ways, or are very familiar with the area you are in, knowing your declination angle(along with all the other land nav skills) is not that important. However, if you are attempting long range, precision land navigation, it is a must. Depending on where you are at, the difference between magnetic north and grid north could be substantial, and WILL be the difference between hitting your mark, and being possibly thousands of meters away from where you wanted to be.

There are a lot of skills associated with land navigation besides knowing your declination angle: Pace count, plotting a course, knowing how to perform intersection, and resection, how to properly shoot an azimuth/back azimuth, and sadly, knowing how to properly read a map.

Yeah I should have made it more clear that my experience is just for my area. Having stated that when I was a teenager in the early 70's myself and my brother in law went coon hunting with an old man (don't remember his name) and it was pitch black no stars, no light of any kind even the wheat lights didn't shine very far.(old man had a carbide lamp) and the dogs came in whimpering, they didn't like the dark either. I was completely turned around as well as was my brother in law, but the old man lead us right to the truck with his compass. Now we are talking river bottoms. They get really, really dark on a moonless starless night.

I'm more than confident that I can find my way out of any situation just by knowing the cardinal points and being familiar with the terrain that I inhabit. Will I pay the ultimate price for being wrong (perhaps), but confidence is a key factor. The compass has had a relative short life on this planet as opposed to other means of discerning direction.

[FranchiseKid]

I give a dissertation on sythetic debt obligations and transporting alpha but I have no clue how to use a compass and a map. Ugh.

[cmarjeep]

Originally Posted by Eyebone

I was talking to a guy at work last week who professes to be an avid hiker.

I asked him if he had a compass, he said "yes" but couldn't tell me what sort.

Then I discovered he did not know the declination for this area.

Well the magnetic declination for Seattle is 18.3 degrees west.

Here is a web site that lists MD for all cities across the continental United States.

http://www.dvbresource.com/charts/ci...eattle-WA.html

Seattle is actually 18.3 degrees east.

[Eyebone]

I shouldn't comment on this but, what do you have, dyslexia?

[anchorbanger]

This sorta sums it up....

http://en.wikipedia.org/wiki/Magnetic_declination

[Texas Patriot]

At the risk of incurring great peals of laughter ,I have a couple of questions ,If I may. I don't really know how to use a compass but I am reading a book on it. That site is an excellent resource! I know what declination is but am unfamiliar with the terms :Apex declination,and declination offset.I know what an "apex" is,how does that apply to declination? Is the term "declination offset" what I think of when I think of the term "declination"? Sorry for the elementary questions, but we all have to start somewhere. TP

[Eyebone]

Apex declination
Declination offset


Refer to reception of satellite signals, which has nothing to do with the compass.

I posted this site because in the past I have had trouble finding the correct declination for various areas.