Polar Opposites – When Compasses Go Bad

Polar Opposites – When Compasses Go Bad



I’m one of those lucky people who has an in-built compass that most times just knows instinctively which way is North. I think I got it from my Dad, as opposed to my Mum who was from the ‘turn-the-street-directory [remember those?] around-until-it makes-sense-and-then-stop-to-ask-for-directions’, school of navigation. These days, I know that my Mum was actually applying a pretty cool navigation hack, which officially is called, ‘orienting the map’ and I talk about it in my navigation course.

Compass reversing Poles

So it was no surprise that on last weekend’s trip to the beautiful Coxs River, I thought my inbuilt compass had gone a little wonky.

compass with poles reversed
Which one of these is not like the other one?

The toppo map, the bend in the river, my inbuilt compass and my trusty reliable Silva compass seemed to be conspiring against my sense of sanity.

I couldn’t understand why Goolara Peak was behind us… it should be in front of us! This doesn’t makes sense.

It was only when my friend came along and we conferred that things suddenly became crystal clear. The photo above says it all. Her compass is the one on the left, whereas mine on the right is showing exactly the opposite. Double confirmed by the electronic compass in my watch.

Who moved Goolara Peak? [Upstream on the Coxs River]

Why do compass poles reverse?

I emailed Silva [Sweden, not the USA company] to find out how to fix this. I’ve heard it’s as easy as wafting a magnet nearby. Here’s the response:

“The reason that your compass is not showing north is most likely due to it being subjected to a magnetic field that has polarized the needle. This is, unfortunately, fairly common in today’s world since we carry a lot of items that emit a magnetic field such as mobile phones, GPS and other equipment. A compass needle cannot change its own polarization, it has to be “forced” to reverse its polarity by a magnetic field. 

We write in the manual that it is very important to check the compass every time it is used since polarizations do happen, it is as important as checking any part of your survival gear before it is used, since your life may very well depend on its functions. [Lotsa: Couldn’t agree more… now!]

It is not complicated to reverse the polarization of the needle but to be 100% sure of the result you should be using a controlled magnetic field. Because of this I do not recommend that you polarize your compass by yourself, if you send your compass to us here at Silva Sweden AB we can polarize your compass free of charge, the only cost for you is to ship the compass to us.” 

David, Technical Support, Silva

And so, today my compass which has served me well and I’ve trusted implicitly (until last weekend) will be going on a little Scandinavian holiday…

… I can’t help but think about all the magnetic fields in the aircraft and postal sorting machines between here and Sweden though!

If you want to learn how to use a compass and navigate with a topographic map, building your confidence and making the connection between the land around you and the map, checkout my navigation courses.

Further reading:

navigation course
Oh! That’s me, teaching navigation in the stunning Blue Mts National Park
Bushwalking & Hiking Tips from an Unexpected Outdoors Chick

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