In reply to GW7AAV:
Long ago when I taught physics we used to use those little, about 1/2" diameter compasses for plotting magnetic field. They were always changing polarity.
We used to demagnetise them by putting them inside a solenoid with an AC current through it and reducing the voltage slowly to zero (degaussing?).
We then used the same solenoid, this time with a DC current, to remagnetise them , drawing the compasses through slowly.
The best compass I ever had was an Admiralty Prismatic that my grandad gave me. He had it before WW2 not new then, my son now has it. The nearest I can find to it today is http://www.armynnavy.com/catalog/catalog/product_info.php/products_id/2266 only real difference is night light probably gives off less radiation on new one.
Me too, though I carry a GPSr to log my journey and for APRS tracking. As I have the GPS with me, I programme in important waypoints from Memory Map ‘just in case’.
Which reminds me, my compass has a big bubble in it! I have had three
consectuive Silva compasses where this has happened. Each has lasted
less than two years (mnd you that’s about 400 expeditions!). Does
anyone have a recommendation for a long-lasting, robust and reliable
compass?
I have also suffered from this with Silva’s and also from corrosion of the aluminium capsule surround (no longer a problem these days). Since I bought a Suunto (MC2) about 10 years ago I have had no similar problems.
As a recommendation of both Suunto & Cotswold Camping, I did once remove the needle from it’s bearing due to ‘severe impact damage’. Even though it was well out of guarantee and obviously damaged by myself, Cotswold were so confident of Suunto’s customer service that they exchanged it for a new one then & there in the shop.