Compass - I can't figure this out!

[Lithril]

Ok I've been using compasses for a while and I understand the principles on how they work (have to teach it to 11-16 year olds...) but I'm stumped at this one.

Usually use Silva compasses as they're basic and fairly robust, we give them to the kids for DoE to use. I went out last weekend and there were 3 compasses in the group, the kids had 2 and I had 1, all identicle and made by silva. I put my compass in my top pocket (nothing else in there), next time I took it out to check a bearing, walked about 200 meters and the compass swithced so that north points almost to south and vica verca. Only happeded with this compass and its still like it, so a permenant change.

Any ideas?

Matt

 

[Toddy]

I thought that only happened to me
No idea, though my destruction of compasses has been blamed on walking too near to an electricity sub station, passing under pylons, thunderstorm and my rucksack containing the compass being left too near to a fire. I can't see any of them really being responsible but I'd love to know what reason you finally come up with

Cheers,
Mary

 

[Swede]

It happened to me too. I noticed that the compass showed 180 degrees wrong. For that time i worked in a shop. We had a strong magnet mounted on the desk in the shop to demagnetize the pricetags (prevent shoplifting). By putting the compass on top of the magnet it became "set at zero" and was OK again. I don´t know if a cellular phone or anything else with a strong magnetic field are to be blamed. /Swede

 

[Roving Rich]

Prolly too close to your pacemaker Lith

Cheers
Rich

 

[merlin]

magnets can go a bit funny if they have a bang even a small one, maybe a small bang and its lost some strength allowing it to affected by something small you have on you, watch or something else metal??

 

[oldsoldier]

I think the poles just changed for you!!

 

[The Joker]

I think the poles just changed for you!!

On some tv prog the other day i was watching they said we're suposed to be nearing a time when the poles swap

 

[rik_uk3]

Ok I've been using compasses for a while and I understand the principles on how they work (have to teach it to 11-16 year olds...) but I'm stumped at this one.

Usually use Silva compasses as they're basic and fairly robust, we give them to the kids for DoE to use. I went out last weekend and there were 3 compasses in the group, the kids had 2 and I had 1, all identicle and made by silva. I put my compass in my top pocket (nothing else in there), next time I took it out to check a bearing, walked about 200 meters and the compass swithced so that north points almost to south and vica verca. Only happeded with this compass and its still like it, so a permenant change.

Any ideas?

Matt

Saw the same thing in an episode of the X-Files

 

[Chopper]

You need to re magnetise the needle.

Get a small bar magnet use only the North pole end and place it on the glass dial and then slide it along the glass towards the tip of the north (RED) end of the needle, do this about ten times and it should bring it back to life.

Make sure that you only do it to the red half and not the white half, we used to have a really dopy scout leader and I magnetised the white (South) end of the needle and then gave the compass to him on a hike, it took him about ten minutes to realise that there was something wrong and he never really switched on to the fact that it was a windeup, quite worrying that someone so stupid could be allowed to be responsible for our kids.

 

[Rod]

Hi Lith,

You can send the compass back to Silva and they will realign it for you - also will take bubbles out of the capsule. Take it in to your local Cotswold and get them to send it off for you.

 

[gregorach]

I've had the same thing happen to me. Darned if I could figure out what had caused it...

 

[Lithril]

Hi Lith,

You can send the compass back to Silva and they will realign it for you - also will take bubbles out of the capsule. Take it in to your local Cotswold and get them to send it off for you.

Fantastic, cheers Rod, I didn't realise they would do that, I was going to bin it.



Thanks for the responses.

Matt

 

[BorderReiver]

Bit worrying this.The accepted wisdom is "always trust your compass".

So if you are in unfamiliar territory and you trust a dodgy compass,you could land up in trouble.

Just as well to carry a GPS as backup.

 

[anthonyyy]

I can understand exposure to a magnetic field altering the compass and putting it a bit "off" but an 180 degree change is wierd.

 

[Chance]

Would it have been near a phone ? Or anything else with a speaker in it ?

 

[FGYT]

Bit worrying this.The accepted wisdom is "always trust your compass".

So if you are in unfamiliar territory and you trust a dodgy compass,you could land up in trouble.

Just as well to carry a GPS as backup.

which is why you should always carry 3

 

[Chopper]

Fantastic, cheers Rod, I didn't realise they would do that, I was going to bin it.



Thanks for the responses.

Matt

When i asked Silva direct if they could remove bubbles they said that it could not be done, and why go to the tropuble of returning the compass when you can fix it yourself in two minutes.

 

[Lithril]

When i asked Silva direct if they could remove bubbles they said that it could not be done, and why go to the tropuble of returning the compass when you can fix it yourself in two minutes.

The trouble with trying to induce a magnet by this method is that they're more prone to losing magnetism through bumps and over time. Permenant magnets are normally electrically induced from what I can gather.

 

[Chopper]

The trouble with trying to induce a magnet by this method is that they're more prone to losing magnetism through bumps and over time. Permenant magnets are normally electrically induced from what I can gather.

Go with your own choice, but about three years ago I remagnetised two of my own Silva compasses and have done several for the scouts and they are still working fine.

 

[Glen]

Bit worrying this.The accepted wisdom is "always trust your compass".

So if you are in unfamiliar territory and you trust a dodgy compass,you could land up in trouble.

Always worth checking, with the Sun, to make sure your compass hasn't done a pole swap.