I’ve always taken stories of compass reverse polarity with a degree of scepticism as I’ve never personally noticed any problems. But, in preparing for this year’s Challenge, I was thinking of keeping my compass in a hip belt pocket along with my camera so I decided to see what effect it had. My expectation was that any effect would be so small as to be irrelevant. I was astonished – there is a major magnetic effect (about 50 degrees)as you can see in the pictures below. How long it would take to reverse the polarity, I don’t know but for sure it is a possibility.
I also tried other devices – a SPOT tracker which had no effect whatsoever and an iphone, which had a very minor effect. Probably too small to reverse polarity but I wouldn’t risk it. So – be careful and don’t keep your compass in the same pocket as your camera.
Wow. Thanks for sharing the info Ian.
It happened to me in the Picos about three years ago. In my case I had my compass in a pouch on the rucksack shoulder strap – well away from cameras and the like, but unfortunately right next to the magnetic clip on my new Osprey hydration thingy.
Navigation became a right mucking fuddle until I figured out why the sun had moved!
Great info Ian – I was always aware of it but never seen it demonstrated so starkly. Last weekend on Culardoch I made sure to stow my compass in the same pocket as my wind gauge, but not mobile phone. Anything with a ‘large’ battery in it will have a magnetic effect.