Magnetic Zones & Global Compasses
In my search for a new compass for my big trip I have discovered a fact that I wasn't aware of and maybe worth repeating here because compasses are a critical item of equipment and
a)others might not know about it, or
b)I may be a naieve idiot in need of putting straight.
Basically, it goes like this..
The earth is dived from north to south into a number of magnetic zones or 'slices'. These relate to how much the needle dips toward the magnetic pole. When you buy a normal compass, the needle will be balanced for a particular zone, usually marked on the back as MN (magnetic north), NME (north magnetic equator), ME, SME, MS. If you try to use it in a zone at a largely different latitude, the needle will hit on the case because it will be unbalanced. i.e. Your compass bought in North America will not work in Australia. If anyone can confirm that they have actually experienced this problem it could be enlightening.
There are 'global' compasses on the market that use different patented techniques to enable them to work in all zones.
I was looking for mirror sighting compasses with a clinometer and declination adjustment and I found the Silva Voyager 8040 but I'm not that keen on it because it doesn't have a transparent baseplate (good for working from maps). I also found the Suunto MC-2G and the Recta DS56. These both have transparent baseplates and are my preferred choice. The Recta and the Suunto look very similar and I read that Recta are part of the Suunto group so they might actually be the same compasses marketed under differnet names. Does any compass experts out there know?
Also, has anyone used compasses from Suunto or Recta and can vouch for their quality? I have only ever used Silva and that was a long time ago. They all claim to be 'world leaders', but the proof of the pudding....
Sorry if that was all a bit long winded.