Caring for a Compass?

S

Scott Free

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Sep 15, 1999
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I got a Tru-Nord compass for Christmas, and I'm wondering what precautions (if any) I might need to take regarding carrying it, and storing it. More specifically, can I safely carry it in my pocket with other metal objects without affecting the compass? What if one of those objects (such as a pocket knife) has been magnetized?

What about storing it? Should I store it away from magnetic fields? Or doesn't it matter.

Scott
 
I would keep it away from magnets to be sure. When I was a kid, I rubbed a magnet over a compass several times and managed to reverse polarity on the needle, then the north end of the needle pointed south. I was able to reverse it later the same way. I don't think carrying it with metal objects only would affect it much, but if those objects were more than sightly magnetized, I would think twice.
 
Keep it away from magnets. That's all.They're rugged and can take a little abuse.

I just put mine into a sock drawer.
 
I ask the question because I once had a cheap plastic compass reverse its readings. North pointed South. I don't know how it happened.

When I put my new Victorinox Farmer around the Tru-Nord, it has no affect. When I move my old Vic Rucksack around it, the compass goes crazy. I can keep the two in different pockets, but I'm thinking this might make my Farmer my new edc for the woods.

Is there any way to demagnetize a knife?

Scott
 
There's been some discussion about the issue in the Wilderness & Survival forum. I guess I'll move this thread there.

You could demagnetize a knife with a bulk tape demagnetizer (used to erase tapes and floppy disks). I don't think a wand head demagnetizer would have much effect.

moving-van.jpg
 
Now just buy the book Be Expert with Map and Compass by Björn Kjellström so you can master the art of using that awesome little button compass!

He has dedicated sections on how to use a button compass as a stand alone and with a map.
 
I reversed the polarity of a compass (Silva, as I recall...but that doesn't really matter) by carrying next to the speaker/magnet of a micro cattette recorder.

Luckily my ex-girlfriend held her ground and got us pointed back in the right direction.
 
Scott Ridgeway said:
I got a Tru-Nord compass for Christmas, and I'm wondering what precautions (if any) I might need to take regarding carrying it, and storing it. More specifically, can I safely carry it in my pocket with other metal objects without affecting the compass? What if one of those objects (such as a pocket knife) has been magnetized?

What about storing it? Should I store it away from magnetic fields? Or doesn't it matter.

Scott
Click to expand...


As a surveyor for a large part of my life I own many compasses, (cheapies to pocket transits) several reside in my b.o.b.s and have for decades, along with all manner of knives, firestarters, flashlights, firearms, ammo, mags, water filters, candle lanterns and glow-sticks (to name a few items in there).

Not a one of them has ever been harmed or rendered un-useable from close contact with metal objects.

mike

ps - ever notice what the "body" of most mil spec compasses (no matter the country of origin) are made of...........

I own quite a few, US, swiss, e.german, hungarian, rusky - all have metal bodies
 
First thing to do with your new compass is to check that it reading correctly by verifying a bearing with a known accurate compass or GPS. If it reads incorrectly, either return it to the dealer or have a specialist instrument fitter recalibrate it. (Recalibration may not be cost effective for an inexpensive button compass)
In my experience, carrying a compass in close proximity to metal objects, even over a long period of time, does not affect the accuracy.
Magnets, however are a different story. Keep your compass well separated from things like cell phones, pocket tape recorders or headphones as their magnetic field can permanently disrupt your compass.
A knife blade that is magnetized will affect the compass only if it is kept nearby when taking bearings, but again it would be a sensible precaution not to carry or store the two together.
No special care required, keep it clean and dry, and just drop it in a drawer to store it away. I have an old military compass that is nearly 40 years old, and it is as good as the day it was made, despite being well used and never being treated as a "fragile" item.
 
Another caution: keep your compass away from those 2-way radios that are so popular these days. There are strong magnets in those, for the speaker I think.
 
Keep compasses away from compasses. On a Sar exercise we had one person go in circles because the button compass of his PSK effected the trecking compass around his neck.

I had an instance where i was reading a compass and not realizing i was holding it over the compass in my Hiking staff this put me about 5-10 degrees off but really messed me up on a compass course.
 
At my school we have a box which holds 30 compasses, about 1/4" apart. The compasses have never been bothered by this. I even have a small button compass on the front of my knife case (carbon steel) and it hasn't been affected.
Oldman/Marty
 
Two different issues: one is using the compass and the other is storing the compass. Storing compasses together should not hurt them, there will be a magnetic field in the drawer/box but it shouldn't hurt them. When compasses are in the store and stacked on those pegs, they are pretty close together and there's no ill effect. Obviously you don't want to store them with a strong magnet.

In the field, steel and other compasses will cause the needle to vary from magnetic North and will screw up your navigation. Nothing wrong with the compass, it's just aligning itself to the local magnetic field which may be artificially skewed.
 
ras said:
Two different issues: one is using the compass and the other is storing the compass. Storing compasses together should not hurt them, there will be a magnetic field in the drawer/box but it shouldn't hurt them. When compasses are in the store and stacked on those pegs, they are pretty close together and there's no ill effect. Obviously you don't want to store them with a strong magnet.

In the field, steel and other compasses will cause the needle to vary from magnetic North and will screw up your navigation. Nothing wrong with the compass, it's just aligning itself to the local magnetic field which may be artificially skewed.
Click to expand...

+1.

I have three that are rubber banded together, with out any affect that I notice.
 
I have had a tru-nord compass for two years. When hunting I have it in my front pocket of my coat with a bunch of other stuff, folding knife, firesteel
spare change etcWhen i go off the trails to follow deer sign I take my heading
and that little brass compass has always and I mean always brought me back to the trail or damn near close every time. Other than the little nibs wearing off the sides (just a little ) all I do is wipe the dial with my shirt.
 
I read somewhere :)confused: ) that storing a liquid-filled compass in a very hot space (inside a car in the summer sun) increases the chance of bubbles.
 
I think the big issue with compasses and magnets occurs when they are close together and in motion with each other. That's when the risk of re-polarization(?) is present. The incident I reported in post 2 occurred when I rubbed them past one another, and I reversed it again the same way. And from what I remember it didn't take long. Stacking two compasses together and leaving them that way will likely not cause any change, but put two of them together in your pocket/pouch/pack and hike for a while and things might be different. I always carry at least two, and they are never in the same pocket, nor anywhere near my radio.
 
Thomas Linton said:
I read somewhere :)confused: ) that storing a liquid-filled compass in a very hot space (inside a car in the summer sun) increases the chance of bubbles.
Click to expand...

May be true, but Silva says bubble formation has no effect on the compass working.
 
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