Article: Member Review - Silva Expedition Compass

[Tiley]

The needle on those compasses are not actually magnetised at all. How it works is that the pivot has a needle with a magnet underneath it, they both rotate separately and independently of each other, the magnet itself absorbs the vertical force of the magnetic field so the needle is unaffected and stays horizontal. The magnet rotates the needle above even though it is not connected to it and the needle remains level due to magnet absorbing the vertical pull.

Brilliant! Thank you very much for the explanation. I have to admit that, up until now, my only concern was that it worked and helped me navigate accurately; now I have a clearer understanding of how it works which is always a good thing!

 

[Jared]

I have a Suunto Gobal compass and it has a balanced needle that keeps it level, no matter which hemisphere you find yourself in - a bit like the gimbals on a ship's compass. The needle is, as far as I can judge, magnetized in the normal way; if it weren't, how would it point north?

It seems difficult to find how they actually work, but they definitely have a separate magnet doing something

"In the global compass, this problem has been solved with a structural innovation. The needle and magnet are built as separate units functioning independently from each other, so that the inclination of the magnetic field cannot tilt the needle. The needle can no longer move vertically. It is the compass magnet, separated from the needle, which absorbs the vertical force of the magnetic field. The needle itself is fixed at the lid by means of a double jeweled bearing. The magnet rotates with its jewel bearing on a pin. Such a compass works reliably in all zones of the world. Due to the strong magnet, the needle settles very quickly and stops immediately at the right position, allowing for an extremely accurate reading."

- http://www.mapworld.co.nz/global.html

Edit:
Doh slow posting

 

[homesicksteve]

PS Just discovered that this compass is available from The Orienteering Shop in the UK, I have no connection to them, but it's the only UK supplier that showed up on google.

Thanks for posting this review.

I bought one of these from The Orienteering Shop.
No affiliations etc. The service is first class & recommended.

 

[Bark]

Good review.
Thanks for posting.