The Magnetic Compass.......

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Silverclaws2

Tenderfoot
Dec 30, 2019
72
38
52
Devon
And so it was I recently received yet another compass purchased from a certain popular auction website, an old Recta matchbox compass from the 1970's I think, maybe a DP5, purchased primarily for interest's sake as they had been on my radar back in the day. Anyway on reading the supplied instructions that it came with I understood this compass may well have had a fluid filled capsule at one time, not there was any sign of there ever having been fluid in the compass I had just bought, to think, hmmm, maybe I should just fill it anyway to deal with that extremely slow to settle needle.

So off online I went to find out about filling compass capsules, to also come across the suggestion that it's compasses with weak magnetism that don't settle as quickly as one would like, to then go off in search of what to do with weak magnetism in compasses. To find two methods of achieving thus, a method involving a bar magnet and a method involving electro magnetism, of which to me seemed the better option, but because I had a strong bar magnet handy, I gave it a go, to find yes indeed it did improve the north pointing and settling speed even in an un-damped compass, a quite stunning improvement in fact. To then think I will just go and check this magnetic north seeking ability with one of my other compasses, to find the first one selected pointed in a different direction, to then try another to find the same and finally my decent Suunto MC-2 to find, guess what that was different too, for all of them to be indicating magnetic north to be in a different direction - AAARRRGGH

For then the thought to arrive, what if one only had one compass, to trust that one compass in the belief that it was true, when it stands compasses can lose their magnetism over time and can even be motivated to point into entirely different directions by the electro magnetic fields our twenty first century living brings. And yes for interest I did use one of compasses around my desk, to find out just what was emanating a magnetic field, for the question to then come ' how the hell can I store these potential life savers to be in a position to trust them when they're needed, to have concluded unless I bury them in the middle of a field of known geology, not much chance of that, to then think, perhaps I need to polarise the compasses before I take them out, to be in a position to put trust in them, particularly after what I have just discovered.

So for other that uses compasses, how'd you know your compass is pointing true?
 
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Robson Valley

Full Member
Nov 24, 2014
8,665
1,626
McBride, BC
There's a global agency which sets the position of the North Magnetic Pole, every few years.
Most recently, they announced that the NMP is galloping westward like nothing recorded before.
So what you might read as the NMP offset on the corner of a topo map is well off the mark.

I can see Polaris from my front doorstep on any clear night.
It is directly above the Stop sign at the end of my street.
My Brunton Eclipse prototype has an offset of about 25 degrees. I forget exactly.
It has a little disk magnet which I expect to outlast my lifetime.

Outside on my doorstep, I do see the geographic North with my Brunton
and my 1965 Recta Prospector. Bubbles and all.
 
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Paul_B

Bushcrafter (boy, I've got a lot to say!)
Jul 14, 2008
4,655
699
Lancashire
Not saying you are doing this but comparing two compasses by holding them alongside each other will allow the two to affect each other. It's probably something you know about but worth mentioning just in case. Plus there's electrical devices that can affect it as you've experienced.
 

Robson Valley

Full Member
Nov 24, 2014
8,665
1,626
McBride, BC
Find Polaris from a fixed position that you can remember. Your compass should hit this,
provided that you made the correct magnetic offset. Keep away from ferrous metals.
 

Silverclaws2

Tenderfoot
Dec 30, 2019
72
38
52
Devon
Not saying you are doing this but comparing two compasses by holding them alongside each other will allow the two to affect each other. It's probably something you know about but worth mentioning just in case. Plus there's electrical devices that can affect it as you've experienced.
Yeah I am aware of that, to have tested each compass one at a time in the same position and yeah I know about the electromagnetic fields in a house to have used a compass in finding them.

But anyway, I found the stroking of a bar magnet over one of the compasses, the Recta caused it to point in a different direction, to be considering seeing if my old bench power supply still works, to do this ;

Re-magnetising a navigation compass using electro magnetism

To at least know they stand more chance of being true thereafter
 
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Silverclaws2

Tenderfoot
Dec 30, 2019
72
38
52
Devon
Find Polaris from a fixed position that you can remember. Your compass should hit this,
provided that you made the correct magnetic offset. Keep away from ferrous metals.
I understand this year, for the first time in 360 years true north and magnetic north align at the Greenwich meridian, to know the mag offset in my part of the world is currently thirteen minutes east of grid.
 

Robson Valley

Full Member
Nov 24, 2014
8,665
1,626
McBride, BC
I have no idea what the offset is for me here at 53N and about(?) 102W.
It's on all the map sheets plus a number for yearly change.
However, since it's moving so fast, none of that stuff is relevant any more.
I guessed that it all has to line up 00 - 00 for somebody!

That's OK. I don't do any more overnight stuff since it's convenient to drive home,
living in the middle of forested mountains.
It's easy to say we just look up at familiar mountain peaks
but it doesn't work that way in fog, heavy rain or snow storms that come up in 60 seconds.
My Brunton has set me right twice when I really believed that I knew my course. Wrong.

I've just bought a couple of average compasses and 8x25 porro binocs for my twin grandsons' birthday.
Wish I could travel to be with them for a day in the park.
 

Paul_B

Bushcrafter (boy, I've got a lot to say!)
Jul 14, 2008
4,655
699
Lancashire
@Silverclaws2
I didn't doubt that you knew that, just thought it worth saying in case others reading it didn't know. I reckon most people who are regularly on this site know more than most about navigation. I also know some of my Google searches have also given links to BCUK threads for answers to my questions. So I believe going back to the basics is worth doing.

Back to topic I've never really thought about remagnetising a compass. I've been on the feels of these lake district and felt my compass was out before. I just got another one because it's about confidence in such an important tool for the outdoors for me. Turns out the faulty and new ones were pointing north in different directions. However the faulty one ended up somehow pointing the same north as the new one after a few years in the cupboard and what I assume the correct direction too since it was checked at home where I'm able you determine north quite easily.

Could leaving the faulty compass over time cause it to somehow self correct? We're taking about 10 degrees out ending up at virtually zero degrees out.
 

Riven

Full Member
Dec 23, 2006
368
76
53
Nottinghamshire
Interesting video, my one question is how much power is needed to re-magnitise? Would a battery work and if so what voltage?
 

Silverclaws2

Tenderfoot
Dec 30, 2019
72
38
52
Devon
@Silverclaws2
I didn't doubt that you knew that, just thought it worth saying in case others reading it didn't know. I reckon most people who are regularly on this site know more than most about navigation. I also know some of my Google searches have also given links to BCUK threads for answers to my questions. So I believe going back to the basics is worth doing.

Back to topic I've never really thought about remagnetising a compass. I've been on the feels of these lake district and felt my compass was out before. I just got another one because it's about confidence in such an important tool for the outdoors for me. Turns out the faulty and new ones were pointing north in different directions. However the faulty one ended up somehow pointing the same north as the new one after a few years in the cupboard and what I assume the correct direction too since it was checked at home where I'm able you determine north quite easily.

Could leaving the faulty compass over time cause it to somehow self correct? We're taking about 10 degrees out ending up at virtually zero degrees out.
What I know is that magnetised things can lose their magnetism over time, for it to make sense compasses may become weaker to perhaps wander around more, to have wondered what a compass featuring a neodymium magnet would be like, I mean some compasses use the mildly radioactive gas ; tritium for luminosity, why not go supercharged with neodymium.

Anyways I feel my way forward with my compasses is to go down the electromagnet polarisation route, perhaps before taking them out to have more faith in them, and faith given what I've found out about them and yes I have seen compasses that have reversed polarity ;

https://lotsafreshair.com/2012/11/07/polar-opposites-when-compasses-go-bad/
 

Silverclaws2

Tenderfoot
Dec 30, 2019
72
38
52
Devon