UKC

Just packing the weekend sac and came across the not so old compass that now has more bubble than oil. Had it about two years. Have a spare that also has a mega bubble. Good makes too (Silva). Previous compass lasted nearly 15 years before bubbles stopped its use.

Am I unlucky, hard on my compass(es) or just expecting too much. Could still use it but only take it out when I really need to and don't want to make navigation more difficult that needs be.

What is the life expectancy of a compass these days ?

In reply to Tubbs:

depends if u use it to jab holes in the desk. The piont goes all blunt pretty quickly them. Never had bubbles though

In reply to Tubbs: They tend to last until I mislay or kneel on them.

In reply to Tubbs:

My Silva compass is about 35 years old, and still in good condition. I don't use it much.

In reply to Tubbs:


A lot longer than when your 7 year old daughter sticks a pile of magnets on top of it.

In reply to Tubbs:

I recall that Silva had a bit of a problem with bubbles a while back. I'm also sure they used to have a five year guarantee. But I can't find that on the Silva website...

In reply to Tubbs:

I believe the compass that hangs around in my day sack is older than me.. They just don't make things like they used to :P

In reply to Tubbs:

My father uses the one his uncle used as a sniper in the First World War. Seems to work OK.

As I type that I find myself wondering for the first time WTF a sniper needed a compass for.

jcm

In reply to Tubbs:

I used my dads old silva compass to teach my daughter navigation.
Theres not much to go wrong with them.

In reply to johncoxmysteriously:

About the wind direction, the forecast may say the wind is changing direction in the afternoon and it is safer to look at one's compass than get out of hiding to see where the wind is blowing. Compensation of the wind has to be taken into account when firing.

In reply to Norrie Muir:

A bit of cotton and feather/piece of fine fabric are a better bet with estimating windage, a very uncertain science at the best of times.
No-mans-land could be miles wide, denuded of mapped features and generally a disorientating place to be - might be a good reason to have a compass...

In reply to desmond_burnett:

Aye, right, you would be a sniper with no kills, as you would he dead.

In reply to Tubbs: should last until the planet runs out of magnetism, or the liquid core stops moving...

In reply to Tubbs: veering back on topic, my dad bought me a silva compass for my 16th birthday which i still use regularly.

In reply to johncoxmysteriously: Was it in mils ? Got one of those too (without bubbles).
Something about the "the angle subtended by one mil at 1000 meters is one meter", useful for estimating distances.

In reply to diggers: Disagree, has stopped working precisely because the liquid core does not stop movement (lol) !

In reply to Tubbs: sorry....I was talking about the liquid core in the earth - which is thought to be the cause of magnatisum

In reply to Tubbs:

Hello Tubbs, I have used Silva compasses for years. They do create bubbles when banged or knocked. Best thing I found was to place them on top of a radiator (heat gets rid of the air bubbles). You could use your other compass to check the accuracy afterwards.

PS mine is around 18 years old and still going strong!!

All the best.

In reply to Tubbs:

I have an extremely accurate ship's compass on my bookshelf. Made in 1832 (rpt 1832) by Jas. Blackley of Dundee. Served both me and my dad during our days at sea. But too big for my current boat.

In reply to johncoxmysteriously: I reckon the only time it would have been safe for a sniper to enter/exit no mans land would have been at night, hence the need for a compass.

All Silva Compasses have a 5 year warranty

Send it back to us at HQ and if it is a faulty one it will be replaced.

Andy

Silva Ltd.

In reply to Tubbs: At least one leg!

In reply to andycl:

Can I send you fifteen (yes 15) Silva compasses less than five years old whose dials have simply worn off as well as many with bubbles? Some got bubbles before they were even out the packet.

Dont know where you make them now but the build quality is frankly crap. As a D of E leader I've got 30 in regular use - not used any more than my own much older type 3 and yet the rate of attrition with newer Silva compasses is unreal.

Can you give us the address of HQ??

In reply to Tubbs:

Bubbles or not, the general knocking around that your compass gets will affect the accuracy of the needle because the magnetism gets "re-set". I'm not explaining this very well (my brain's a bit broken at the moment) but basically after umpteen years your compass will not be 100% accurate. It is possible to find out how "out" it's got, and adjust all your bearings accordingly.

In reply to Becky E:

Interesting. This echoes a conversation I had recently. Can you be any clearer about how "magnetism becomes re-set"?

I can understand how the needle will become less magnetic over time - due to degradation of polarity through knocks as you describe. Surely though it will always settle on true (magnetic) north given a steady, level base and enough time. Lost performance rather than lost accuracy.

In reply to Clwydian:

Sorry, as I said, my brain has broken today.

Basically, you know you can magnetise a pin by repeatedly stroking it with another metallic object in the same direction? This sets all the atoms in the same direction (There is a propeor name for this process. I'm dragging up GCSE physics now - think MRI scanners). Knocking your compass around undoes this, so instead of pointing exactly north, the compass points slightly to one side.

Does that help at all?

In reply to Becky E:

If you got your compass needle out of the housing, and repeatedly stroked it iwth another metal object, you could completely re-set the needle so the north end pointed south.

In reply to Becky E:

I understand what you're getting at and agree to some extent but I don't think Silva (for instance) manufacture their compass pointers by the same process as you magnetise a needle. Or rather, they are much better at it and achieve a much denser magnetic polarity than you ever will at home. Look at the speed the pointer moves and how firmly it holds north once set level. It's hard to believe that even several years of being knocked around in a rucksack could disrupt the polarity to the extent the compass would not point accurately and yet settle on that bearing quickly enough that you wouldn't throw the compass away for that reason first.

In reply to Clwydian: My compass got remagnetised on the tube on the way home. S was N.

In reply to TimR:

I won't ask why you need a compass on the underground.

Is it significant that you had a complete (180 degree) change in polarity rather than just a few degrees? I'm not claiming to have the answers, I just can't understand how a small change could happen.

Do you still have or use the compass? Has it drifted back towards its original polarity at all?

In reply to Clwydian:

But the process used to aligh the atoms (whcih is what happens when you magnetise the compass needle, or a pin) doens't affect the outcome - the atoms are aligned.

If sufficient atoms are misaligned - for whatever reason (close contact with other metals, knocks, etc) then the compass needle will no longer accurately point north.

I guess it depends how much abuse the compass gets, where it is kept, etc.

In reply to Becky E: The process of magnetism is still not fully understood. It is though to be more down to electron spin. It's certainly not due to Atoms.

When I bought my compass it pointed N-S, when I got home it pointed S-N. The only explination was that the electromagnets on the tube had affected it. it took it back and they replaced it.

My numbers on my compass dial wore off due to grit etc before any bubbles or loss of magnetism.

In reply to andycl:

Andy from Silva.

Any comment on the latest direction this thread has taken?

In reply to TimR:

Sorry, you're right - electrons not atoms.

(I did say my brain was broken yesterday).

In reply to TimR:

Did it definitely point correctly in the shop? It could have been a manufacturing defect with the magnetic process.

Come on AndyCL, say it isn't so.

it should last for ever lol as long as u look after it! get a good silva one and they amazing. or u can always go for the gps

In reply to Tubbs:

my Recta Elite Global Compass developed a bubble when it went to spain in my hold baggage on the plane last year, as long as the bubble is not touching the needle it works absolutely fine