Compass Opinions Navigation Help

22-rimfire said:
Do magnetic declination adjustment confuse you? Turn it west or east relative to the N?
Click to expand...
Doesn't confuse me.

I just remember EMGA. East, magnetic to grid, add.

If EMGA, then
EGMS (s=subtract), then
WMGS, then
WGMA.

For the last 40+ years, I've just remembered EMGA.

That said, if your compass lets you set the declination, adjust it and be done with it.
 
That is an easy way to remember it. I suspect many have some difficulty understanding the adjustment versus what it means.
 
22-rimfire said:
That is an easy way to remember it. I suspect many have some difficulty understanding the adjustment versus what it means.
Click to expand...
All one has to do is look at the declination diagram in the margin of most topo sheets.

WARNING THOUGH: declination changes. If your map is old/dated, go to NOAA's website to get the current declination for the area of the topo sheet.
 
As I said, the difficulty is in "understanding the adjustment" or in other words the actual adjusting of your compass correctly versus doubling an error relative to true north. Yes, you can read the declination printed on topo sheets and so forth, but transferring that info to your compass correctly and being 100% sure you did it correctly could be a problem for some. Yes, the magnetic declination changes.

I might add that the reason for the uncertainty is because you make the adjustment so infrequently on a compass. I basically move mostly within a 200 mile radius of where I live and seldom go outside that area except on trips and I'm usually not hiking on trips. I seldom change the declination although there will be some variation west to east in my area of interest.
 
Last edited:
The arrows on the diagram will tell you is West magnetic declination or East magnetic declination.

If magnetic north (MN) arrow is east of grid north arrow (GN) the magnetic declination is East.

An example of an East magnetic declination diagram:
topo_dcl.gif




If magnetic north (MN) arrow is West of grid north arrow (GN) the magnetic declination is West.

An example of an West magnetic declination diagram:
compass_example.gif




The trick is when the GN is on one side of True North and the MN is on the other. You must use the sum of the two angles when converting from grid to magnetic or magnetic to grid however EMGA, EGMS, WMGS, WGMA sill applies. In the case below you'd apply the declination as 21° West.
Fig20_EA56.jpg
 
leghog said:
The arrows on the diagram will tell you is West magnetic declination or East magnetic declination.

If magnetic north (MN) arrow is east of grid north arrow (GN) the magnetic declination is East.

An example of an East magnetic declination diagram:
topo_dcl.gif




If magnetic north (MN) arrow is West of grid north arrow (GN) the magnetic declination is West.

An example of an West magnetic declination diagram:
compass_example.gif




The trick is when the GN is on one side of True North and the MN is on the other. You must use the sum of the two angles when converting from grid to magnetic or magnetic to grid however EMGA, EGMS, WMGS, WGMA sill applies. In the case below you'd apply the declination as 21° West.
Fig20_EA56.jpg
Click to expand...

So in the first example, you will be moving the compass declination adjustment to the 16.5 degrees WEST (westerly direction on the compass scale 350, 340, 330 etc) to match the True North (TN) to magnetic north if the declination is set at compass TN and Magnetic North to start with (ie. zero declination). If matching the UTM grid on your topo, you would move west 16.5 degrees less about 1 degree. Is this correct? OR is it the total opposite to what I am saying? I just seldom change my declination.
 
Last edited:
No when converting azimuths from grid azimuths (MAP) to magnetic azimuths (COMPASS), you don't concern yourself with True North. You need to know the difference between Grid North and Magnetic North. The one degree between True North and Grid North matters not when moving from map to compass or compass to map.


For use with the map and your compass:

-The first diagram shows an East magnetic declination of 16.5°.
-The second diagram shows a West magnetic declination of 8°.
-The third diagram shows a East magnetic declination of 21°
 
Leghog, I know about azimuths or bearings. What I am asking is did I adjust my compass dial correctly for the East magnetic declination in your example #1 or do I have it backwards? I mentioned the azimuth numbers so you would know which side of the North mark I was physically moving my compass to compensate for the 16.5 degree EAST declination. From there I have no problem between grid north, magnetic north, true north and so forth. (I thought this was a simple basic question that might be useful for new people using a compass.) I seldom really use a a topo map other than to check generally about where I am. I seldom sight on anything to try to locate myself. And yes, it is easier to use grid lines (UTM) than lat/longitude.

Added: I bought this up as your previous post said "add" for east declination and "subtract" for west declination. Add or subtract to what? My guess is that adding and subtracting is relative to a measured bearing direction.

Let me give you an example. Let's say that you have your compass set with NO declination. The local declination is 30 degrees EAST. You take a bearing on a tree with the un-adjusted compass using magnetic north and you get a reading of N30W (or if you like Azimuths 330 degrees). To correct that bearing to true north you would ADD and the result would be you were sighting precisely true north or zero/360 on the compass scale. But this does not answer my question of adjusting the compass as I mentioned above.
 
Last edited:
TOMBSTONE said:
I haven't used a compass for navigation since the Military in the early nineties, totally forgot the compass training. I'm thinking about getting back into learning that navigating skill. Looking to get Suunto MC2 Global. What do you experienced compass users prefer to use Metric or Imperial and why? If I get Metric can you navigate maps utilizing different scale and Imperial measure? I'd like to have one compass for any situation or map use. Thanks!
Click to expand...


Hi! I have a Suunto MC-2 Global and I am pretty OK with it :). Have it since three/four years now, it replaced an old Silva. No issues with bubbles so far. Mine is a very minimum, basic use; not so much unexplored territory in my hiking areas :)! More to play a bit with kids, teaching them the basics of land navigation and keeping it up with it myself. Did a lot during my military service (also during early 90ies) and I was participating in recreational orienteering competitions for some times afterwards, but now the compass it’s more a playful diversion during our hikes. You are right! It’s rather easy to forget a “proper” use when not practicing for long time! I keep an easy manual at hand for more "tricky" questions, kids can be challenging :D.

I know Suunto has compasses adjusted for Northern and Southern hemisphere but I went straight for Metric so don't know about Imperial availability, sorry. Anyway you can check this out directly with Suunto C.S.!

xfql8x.jpg
 
Add the 16.5 so the arrow index in the housing points to 16.5 on the bezel vs pointing to N on the bezel.
 
Herlock said:
I know Suunto has compasses adjusted for Northern and Southern hemisphere but I went straight for Metric so don't know about Imperial availability, sorry. Anyway you can check this out directly with Suunto C.S.!
Click to expand...
Compasses aren't "adjusted" for northern and southern hemispheres. The are made to balance the needle in either the northern or southern hemispheres and designed to handle the magnetic dip without the needle dragging across multiple magnetic zones (aka global needle).
 
Last edited:
leghog said:
Add the 16.5 so the arrow index in the housing points to 16.5 on the bezel vs pointing to N on the bezel.
Click to expand...

So using the 360 degree azimuth scale as a reference point in Herlock's post above on an un-adjusted compass, you would be moving to N16.5E (or 016.5 az) or adjusting clockwise versus 343.5 (or N16.5W)? Or simply using bearing notation.... N16.5W or N16.5E in an un-adjusted compass that can be adjusted for magnetic declination.

This is a fundamental question when using a compass for anything other than just getting an idea which direction is which and whether what you think is North is actually North and so forth. That is my dominant use and I suspect the dominant use of 90% of folks who carry a compass in the woods.
 
Last edited:
22-rimfire said:
So using the 360 degree azimuth scale as a reference point in Herlock's post above on an un-adjusted compass, you would be moving to N16.5E (or 016.5 az) or adjusting clockwise versus 343.5 (or N16.5W)? Or simply using bearing notation.... N16.5W or N16.5E in an un-adjusted compass that can be adjusted for magnetic declination.

This is a fundamental question when using a compass for anything other than just getting an idea which direction is which and whether what you think is North is actually North and so forth. That is my dominant use and I suspect the dominant use of 90% of folks who carry a compass in the woods.
Click to expand...

If you can't adjust the declination on your compass , and you determine FROM THE MAP that you need to move on an azimuth of 10° where the declination is 16.5° East, using EGMS (East declination, Grid azimuth to Magnetic azimuth, Subtract the declination angle) you would set your compass at 353.5° and follow that magnetic azimuth (which would equate to following 10° on the map grid).

Similarly, if you sight an azimuth on your compass to a distant peak and that COMPASS azimuth reads 50° magnetic to that distant peak, when plotting that azimuth on the same map, you would plot 66.5°on the map. EMGA --- East declination, Magnetic azimuth to Grid azimuth, Add the declination angle).
 
mistwalker said:
I may just spent the money on a Brunton pocket transit and deal with the weight...
Click to expand...

Overall it won't be so bad, because you wallet will weigh significantly less. I picked this up for 12 bucks at a flea market. Takes some gymnastics to work in mils, but the theory is all the same. I too like the mirror for for things other than navigation.

IMG_1577-X3.jpg
 
Thank you Leghog. You see, you always just said "east" or "add" or "16.5", but 16.5 could be N16.5E or N16.5W in terms of a compass. That is precisely what I was asking and now it is clear. If anyone else has any uncertainty adjusting the declination on a compass, your last post made it fairly clear. I was correct in my thinking all along in terms of setting the declination on the compass (ones that have that ability) and adjusting bearings or azimuths on a map using magnetic north. I have been doing this a long time, but since I don't adjust the declination often or even worry about precision in terms of a compass bearing let alone plotting that on a topo map, uncertainty comes into play for me and you confirmed that my thinking was correct.

If you adjust the declination incorrectly, you have doubled the error in bearing directions.

I have a Brunton pocket transit that my boss gave me 40 years ago. It was an old one at the time and he wanted a new one. Still works perfect after all these years. The mirror is cracked. Otherwise it is in perfect condition.

You are essentially matching magnetic north and true north when adjusting the declination. To visualize, you can exaggerate the angles and that helps if you are uncertain. You do the same thing with grid north.
 
Last edited:
I'm one of those 90% folks. Uncle Sam taught me to correct bearings for declination to remember: "WEST is best (+) EAST is least (-)"

Example: Assume the declination is 20 west, and you have determined from your map that you must travel a Grid Bearing of 90 degrees to reach your objective. Since Magnetic North is 20 degrees west of True North, you must add 20 degrees to the Grid Bearing to determine the correct Magnetic Bearing - in this case, 110 degrees.
Set your compass at 110 degrees and turn until the red end of the needle lines up with the N mark on the compass dial.

Conversely, if you wish to convert a magnetic reading taken on the ground to a Grid Bearing on a map, you simply subtract 20 degrees.

If the Declination is 15 degrees east - that is Magnetic North is 15 degrees east of True North, you reverse this process, subtract 15 degrees from Grid Bearings to determine Magnetic Bearings, and adding 15 degrees to convert Magnetic Bearings into Grid Bearings.

I'm just trying to keep things simple (for me) for basic land navigation. Thanks for sharing all the information in this post, I really enjoy seeing the pictures of the different compasses that people use; that Norwegian Marching Compass of Leghog is awesome. :thumbup:
 
Even though I probably own 5 or 6 compasses, I generally only use my Brunton 8040G which has been discontinued and it cost something like $20 at the time. It is one that you rotate the dial to adjust for declination whether it be grid north or magnetic north. It actually has markings that say "east declination or west declination" on the bevel. I keep a little Victorinox mirrored compass in my work field bag to confirm directions when I am working as I might reference something as the northeast side of a building or whatever. So, I need to at least know for sure my orientation.
 
From Wiki

North American trademark dispute
After the founding of Silva USA in 1946 and Silva Ltd. in Canada two years later, both affiliates were later acquired by Johnson Wax Associates, later Johnson Camping, Inc., and by 1985, Johnson Worldwide Associates (JWA). From 1980, JWA had imported Swedish-made compasses manufactured by Silva Production AB for sale in North America.

In 1996, a decision by Silva Production AB to end sole distribution of its Swedish-made Silva-brand compasses by Silva USA led to a court battle the following year between JWA and Silva Production AB (Silva Sweden AB).[9]

In 1998, JWA and Silva Production AB of Sweden reached a settlement whereby JWA retained the exclusive right to sell compasses under its Silva trademark in North America, made by unnamed manufacturers.[10] JWA also retained the North American rights to some product names such as Ranger, Polaris, 1, 2, 3 and others commonly used and recognized in the U.S. and Canadian markets and made popular during the time Silva Production AB was manufacturing Swedish-made Silva compasses for JWA in North America.[11] JWA was eventually renamed Johnson Outdoors, Inc.

For its part, Silva Production AB/Silva Group retained the right to manufacture and sell compasses, GPS tools, and other navigational products under its Silva trademark outside the United States and Canada, as well as market its Swedish-made compasses and GPS tools in North America under the Brunton, Elite, and Nexus brands. The Swedish firm also retained the right to state on Nexus packaging and in the Nexus catalog that Nexus compasses were made by Silva Production AB, but did not retain the right to advertise this fact.[11]

In 2009 Fiskars sold Brunton Inc. to Fenix Outdoor AB of Sweden, and in consequence, Silva Production AB stopped exporting Silva of Sweden compasses to North America under the Brunton and Nexus brands, and halted further imports of Brunton products to markets outside North America under the Silva brand. Currently, Silva of Sweden AB no longer distributes any of its compass products to the USA or Canadian markets.

Current activity
In 2006, Silva was acquired by the Finnish Fiskars Group.[8] Silva Sweden AB retained its own corporate identity as an outdoor products manufacturer within Fiskars under its Gerber Legendary Blades Division.[8]

In 2009, Fiskars sold Brunton Inc. to a Swedish company, Fenix Outdoor AB.[12] After divestiture, Brunton closed out its Nexus and Elite compass lines and discontinued the Brunton 54LU compass, all of which were relabeled Silva of Sweden products, and discontinued imports of the Silva Multi-Navigator GPS sold in North America as the Brunton MNS. These actions left Silva of Sweden without a North American distributor for its Swedish-made compasses and GPS tools. As a result, Silva of Sweden compasses and GPS products are no longer available in North America.

In 2011, Fiskars sold Silva Sweden AB to Karnell AB, a Swedish investment group.

Today, the Silva Group consists of the parent company, now called Silva Sweden AB, together with its subsidiaries Silva Ltd. in the United Kingdom, Silva France, Silva Deutschland, and Silva Far East. The core activities of the Silva Group consist of design, development, manufacture of compasses for land and sea and sales of compasses, GPS and outdoor instruments, headlamps, binoculars and other electronic navigation equipment.
 
Brunton TruArc 7 Global Compass

PRODUCT HIGHLIGHTS

Globally Balanced
2° Resolution
Waterproof to 300' Deep
Imperial and Metric Measurements
Sighting Mirror & Clinometer
Tool-Free Declination: ±180°

< $20.00

Silva Ranger CL Compass.
This fantastic Ranger compass is an essential accessory to have for when you're on hiking trips, boating trips, orienteering, or simply enjoying the great outdoors. It comes with 1:24,000, 1:25,000, and 1:50,000 scales for quick and easy plotting, as well as 1/20 inch and millimeter scale for mapping.
 
Last edited:
You must log in or register to reply here.
Back
Top