Map and Compass, Declination - Page 2 - Survivalist Forum
Survivalist Forum

Advertise Here

Go Back   Survivalist Forum > >
Articles Classifieds Donations Gallery Groups Links Store Survival Files


Notices

Advertise Here
Reply
 
Thread Tools Display Modes
Old 08-25-2019, 01:29 PM
Cabinet Maker's Avatar
Cabinet Maker Cabinet Maker is online now
VIP Member
 
Join Date: Sep 2012
Location: SoCal
Posts: 5,767
Thanks: 20,454
Thanked 12,831 Times in 4,190 Posts
Default



Advertise Here

I don't think I've ever had a broken compass that didn't give me a visual clue...
Quick reply to this message
The Following User Says Thank You to Cabinet Maker For This Useful Post:
Old 08-25-2019, 01:41 PM
Justme11's Avatar
Justme11 Justme11 is online now
French Prometheus unbound
 
Join Date: Jul 2013
Location: Houston
Posts: 26,851
Thanks: 29,461
Thanked 63,870 Times in 19,658 Posts
Default

Quote:
Originally Posted by Cabinet Maker View Post
I don't think I've ever had a broken compass that didn't give me a visual clue...
Yup, if the needle no longer swings freely, it is pretty obvious.
Don't need a special trip to a special holy compass temple to figure out you have a broken compass.

The people that initially explored and founded this country did so without holy compass checking shrines. And they seemed to do just fine.
Quick reply to this message
The Following User Says Thank You to Justme11 For This Useful Post:
Old 08-25-2019, 01:41 PM
bunkerbuster's Avatar
bunkerbuster bunkerbuster is offline
VIP Member
 
Join Date: Dec 2013
Location: Out west
Posts: 8,677
Thanks: 4,348
Thanked 21,846 Times in 6,861 Posts
Default

Quote:
Originally Posted by Cabinet Maker View Post
I don't think I've ever had a broken compass that didn't give me a visual clue...
LOL..... yup, sort of like a broken windshield right in your face

Compass's without a needle dampener that activates when you close the lid, can become very inaccurate after bouncing around in a glove box for a long time (because the needle begins to drag badly).

Then its time to replace that compass, with a far better one.....

Same goes when a liquid filled compass develops big air bubbles inside it.
__________________
Itís dangerous to be right, when the government is wrong. The price of freedom can be seen at your local VA hospital.

Quick reply to this message
The Following 3 Users Say Thank You to bunkerbuster For This Useful Post:
Old 08-25-2019, 02:58 PM
Don H Don H is offline
Survivor
 
Join Date: Oct 2012
Posts: 2,658
Thanks: 3,834
Thanked 6,046 Times in 1,763 Posts
Default

East is Least (subtract declination from you bearing)
West is Best (add declination to you bearing)

http://www.geog.ucsb.edu/~kclarke/Ge...eclination.pdf

Most maps have True north lines but some maps are line magnetic. You can draw your own magnetic lines.
Some compasses allow you to adjust for this.
Quick reply to this message
Old 08-25-2019, 05:11 PM
JDH's Avatar
JDH JDH is online now
Si vis pacem, para bellum
 
Join Date: Apr 2012
Posts: 6,425
Thanks: 657
Thanked 9,933 Times in 3,816 Posts
Default

Quote:
Originally Posted by Wolf6actual View Post
Not a "nit", you made it sound like the entire coasts were 20 degrees...and you were wrong.
No, you read it that way and you were wrong.
Quick reply to this message
The Following User Says Thank You to JDH For This Useful Post:
Old 08-25-2019, 07:36 PM
Don H Don H is offline
Survivor
 
Join Date: Oct 2012
Posts: 2,658
Thanks: 3,834
Thanked 6,046 Times in 1,763 Posts
Default

Here's a site where you can enter a location and get the current declination.
https://wwcan control youw.ngdc.noaa...magcalc.shtml?
Quick reply to this message
The Following User Says Thank You to Don H For This Useful Post:
Old 08-25-2019, 07:48 PM
Snyper708 Snyper708 is offline
Hunter
 
Join Date: Dec 2017
Posts: 1,497
Thanks: 0
Thanked 2,264 Times in 884 Posts
Default

Quote:
Originally Posted by Wolf6actual View Post
Not a "nit", you made it sound like the entire coasts were 20 degrees...and you were wrong.
Wow.
That's never happened here before.
It's a good thing you caught it.
Quick reply to this message
Old 08-25-2019, 07:49 PM
Snyper708 Snyper708 is offline
Hunter
 
Join Date: Dec 2017
Posts: 1,497
Thanks: 0
Thanked 2,264 Times in 884 Posts
Default

Quote:
Originally Posted by Don H View Post
Here's a site where you can enter a location and get the current declination.
https://wwcan control youw.ngdc.noaa...magcalc.shtml?
All I get is:
Quote:
This site can’t be reached wwcan%20control%20youw.ngdc.noaa.gov’s server IP address could not be found
This site if great and can use your phone or computer to determine the declination for your location.

https://www.ngdc.noaa.gov/geomag/declination.shtml
Quick reply to this message
Old 08-25-2019, 08:41 PM
cavedweller's Avatar
cavedweller cavedweller is offline
begger of beer
 
Join Date: Mar 2011
Location: The woods of north Florida.
Posts: 618
Thanks: 309
Thanked 904 Times in 391 Posts
Default

Quote:
Originally Posted by oldwildheart View Post
.
Again, where is the need to be concerned about declination, where do I need to be concerned about declination?
The importance of declination really depends on where you are in the world. If you are in the Midwest, well Magnetic North and True North are almost lined up. So there is not much difference. If you were in Newfoundland or Alaska, True North and Magnetic North are going to be in two totally different directions. Sometimes 20-35 degrees or more.

Like where I am at in north Florida. The Magnetic pole is about -5.7 degrees. If I want my compass to point towards True North, I have to do one of two things. Either add about 6 degrees into my azimuth. If I can adjust my compass, swing the box for the arrow to the left by about 6 degrees.

Attached a map of declination. Maybe the visual could help with understanding.

-K
Attached Thumbnails
Click image for larger version

Name:	0EBBF8AE-6189-43B7-AE06-313E34455255.gif
Views:	25
Size:	27.7 KB
ID:	290900  
Quick reply to this message
The Following User Says Thank You to cavedweller For This Useful Post:
Old 08-26-2019, 12:50 AM
jchavasu's Avatar
jchavasu jchavasu is offline
Nunquam Non Paratus
 
Join Date: Aug 2016
Location: That's classified...
Posts: 1,040
Thanks: 4,615
Thanked 2,304 Times in 830 Posts
Default

Quote:
Originally Posted by oldwildheart View Post
But if I have oriented the map with my compass so that the Grid North line are lined up with the Magnetic North of the compass doesn't that take care of the difference of declination of Grid North and Magnetic North?
No, if you line up the map grid lines with the edge of the compass, then the map will be pointed towards magnetic north. You can shortcut it by using the compass rose that shows the declination and lining your compass up to that, which will take the declination into account. And if the compass has a rotating bezel as I'm sure it does, then you need to be sure that is correctly lined up. There are a lot of ways to go wrong with a map and compass. It is really not as easy as just "pointing it north" as people like to think.

For example, there is True North, Magnetic North, and Compass North. The last is mostly related to Marine navigation. You need to know how to convert one to the other, etc and to make sure you are using the correct version of "north". My grandfather was a Merchant Marine and explained it to me when I was a kid and gave me a mnemonic to remember. "True Virgins Make Dull Company, Add Whiskey" I started to explain the mnemonic but realized it gets far too down in the weeds, and would just confuse the issue.

There are some really good YouTube videos that can help explain declination (also called variation in Marine navigation) and how to work with a map and compass far better than any of us can without photos/examples/etc.
Quick reply to this message
Old 08-26-2019, 04:46 AM
ROCK6's Avatar
ROCK6 ROCK6 is offline
Survivor
 
Join Date: Oct 2008
Location: Georgia/Afghanistan
Posts: 5,566
Thanks: 6,139
Thanked 12,479 Times in 4,084 Posts
Default

Quote:
Originally Posted by Wolf6actual View Post
Unless you are going really far or the declination is extreme, you won't be very far off. What you need to know is if your compass is accurate, it needs to be periodically verified at a declination station (where you shoot a known azimuth). You are better off learning terrain association to use in conjunction with your map. Nobody hikes an accurate azimuth anyway. And you need to learn to go around large obstacles such as a swamp or other impassable terrain. Learn your pace count too.
This these actually the important factors.



I grew up doing land navigation in the PNW where our declination was +18 or so. Unless you're trekking on foot extremely long distances or you need an exact 10-digit grid location while traveling on pretty featureless (or maybe at night) terrain, you can use terrain association to compensate for the declination difference.

The big thing to understand is that magnetic declination does play a factor and is different than the map. Know what that is for your area. Second, study and practice terrain association. Plotting a route and trekking a route on foot are often very much different. You will often have to dog-leg around swamps, find a better river crossing, circumvent a major depression or other significant terrain feature, or simply take an easy ridgeline around vice trekking straight through a valley.

Even with an almost 20-degree declination difference between the compass and map, I could simply use terrain and a rough azimuth to navigate. Do know that the greater the declination, your endpoint accuracy will be more impacted. I recall being a few hundred meters off from a crossroad I was aiming for after moving over a distance of several km's.

ROCK6
Quick reply to this message
Old 08-26-2019, 05:47 AM
surfcast's Avatar
surfcast surfcast is offline
SI vis pacem,para bellum
 
Join Date: Feb 2009
Location: New York
Posts: 1,545
Thanks: 1,270
Thanked 688 Times in 432 Posts
Default

https://www.rei.com/learn/expert-adv...clination.html

This may help
Quick reply to this message
The Following User Says Thank You to surfcast For This Useful Post:
Old 08-26-2019, 05:56 AM
JDH's Avatar
JDH JDH is online now
Si vis pacem, para bellum
 
Join Date: Apr 2012
Posts: 6,425
Thanks: 657
Thanked 9,933 Times in 3,816 Posts
Default

Quote:
Originally Posted by ROCK6 View Post
I grew up doing land navigation in the PNW where our declination was +18 or so.
ROCK6
Learning Land Nav at Ft Sill with the 5 Degree deviation then running the night land nav course at Ft Lewis with your M2 still set at 5 did not work well.
Quick reply to this message
Old 08-26-2019, 09:08 AM
Vodka Wizard's Avatar
Vodka Wizard Vodka Wizard is offline
Prepared
 
Join Date: Oct 2018
Posts: 333
Thanks: 197
Thanked 514 Times in 224 Posts
Default

The best way to deal with declination is to just terrain associate.

I don't remember the last time I kept a pace count. Shoot and azimuth and walk until you get to the terrain feature you identify ahead of time. If you aren't sure, find a hill and shoot a couple back azimuths, take a knee, and drink water.
Quick reply to this message
The Following 2 Users Say Thank You to Vodka Wizard For This Useful Post:
Old 08-26-2019, 05:22 PM
Don H Don H is offline
Survivor
 
Join Date: Oct 2012
Posts: 2,658
Thanks: 3,834
Thanked 6,046 Times in 1,763 Posts
Default

Quote:
Originally Posted by Snyper708 View Post
All I get is:


This site if great and can use your phone or computer to determine the declination for your location.

https://www.ngdc.noaa.gov/geomag/declination.shtml
Try this https://www.ngdc.noaa.gov/geomag/cal...magcalc.shtml?
Actually the same site as you posted but this link takes you directly to the declination calculator.
Quick reply to this message
Old 08-26-2019, 07:58 PM
Vanishing Nomad Vanishing Nomad is offline
Improvise Adapt Overcome!
 
Join Date: Oct 2008
Location: North Aurora, IL
Age: 51
Posts: 11,767
Thanks: 5,556
Thanked 12,100 Times in 5,299 Posts
Default

Quote:
Originally Posted by Vodka Wizard View Post
The best way to deal with declination is to just terrain associate.

I don't remember the last time I kept a pace count. Shoot and azimuth and walk until you get to the terrain feature you identify ahead of time. If you aren't sure, find a hill and shoot a couple back azimuths, take a knee, and drink water.
Thats all I do. I mostly use my compass to get my map in the ball park, and then I compare it to the terrain around me for the final calibration.

Once your map is aligned with the terrain, True North, magnetic north become arbitrary. The important thing is always taking your measurements the same way.

So if you dont adjust for declination at the start, dont adjust for it through out the entire trip.

Its much easier to show this, than do it..because technically, rotating your map into position IS adjusting for declination. You are just making the adjustment at the map, instead of the compass.

To navigate, your compass must point to a fixed position. It must point to that same fixed position every time you take a directional measurement. Since that fixed point (magnetic North) never changes, your measurements will all be correct, relatively speaking.

Just because the bearing you are on is wrong, relative to true north is not relevant. This is because you are not using true north as your fixed point of reference.

Now, that said, if you are traveling a looong distance, to where you will be crossing over areas with different declination, everything changes. This is because your changing position effectively changes your fixed position (true north).

In that case, in order to stay on the correct track, you need a universal fixed point that is true for every area you are traveling through. This means that you will have to use True North, and adjust for the difference between true north and magnetic north as you enter and pass through each area.

This is done because the compass does not actually point to true north. So you have to keep compensating for the error between true north and magnetic north as you move.
Quick reply to this message
The Following 4 Users Say Thank You to Vanishing Nomad For This Useful Post:
Old 08-26-2019, 08:12 PM
Surveyor Surveyor is offline
Target Shooter
 
Join Date: Oct 2016
Location: Florida
Posts: 455
Thanks: 754
Thanked 469 Times in 226 Posts
Default

Nomad got it right.
Quick reply to this message
The Following 2 Users Say Thank You to Surveyor For This Useful Post:
Old 08-26-2019, 08:19 PM
recklessdriver recklessdriver is online now
Prepper elite
 
Join Date: Jun 2010
Location: Lax
Posts: 4,104
Thanks: 770
Thanked 3,549 Times in 1,765 Posts
Default

https://youtu.be/boiQ-XGv-Yg

Pretty easy enough
Quick reply to this message
Old 08-27-2019, 03:46 AM
ROCK6's Avatar
ROCK6 ROCK6 is offline
Survivor
 
Join Date: Oct 2008
Location: Georgia/Afghanistan
Posts: 5,566
Thanks: 6,139
Thanked 12,479 Times in 4,084 Posts
Default

Quote:
Originally Posted by JDH View Post
Learning Land Nav at Ft Sill with the 5 Degree deviation then running the night land nav course at Ft Lewis with your M2 still set at 5 did not work well.
Ah! I remember a group of cadets from OK all standing around a map and scratching their heads talking about how they couldn't see far enough to get a good bearing at Fort Lewis...you might have been one of them if you were there back in 1991

Doing pinpoint land navigation needs a lot more attention on the declination affects (and pace count, and azimuth reading accuracy, nighttime travel, more rugged/thick terrain, etc.). I think the majority of day-time travel is perfectly suited to simple terrain association using a map and double checking the general directions with the compass.

ROCK6
Quick reply to this message
The Following User Says Thank You to ROCK6 For This Useful Post:
Old 08-27-2019, 04:22 AM
recklessdriver recklessdriver is online now
Prepper elite
 
Join Date: Jun 2010
Location: Lax
Posts: 4,104
Thanks: 770
Thanked 3,549 Times in 1,765 Posts
Default

I do way better at terrain association then doing the pace count bs. But yeah it's a good skill to learn
Quick reply to this message
The Following User Says Thank You to recklessdriver For This Useful Post:
Reply

Bookmarks



Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Survivalist Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Gender
Insurance
Please select your insurance company (Optional)

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 10:57 AM.


Powered by vBulletin®
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimisation provided by DragonByte SEO (Lite) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright © Kevin Felts 2006 - 2015,
Green theme by http://www.themesbydesign.net