northern hemisphere compass

[dannnnn]

hi all.. i have a question - do compasses differ between the northern and southern hemispheres? or is it like a left handed hammer?

the reason i ask is that i ordered a heap of stuff from a US camping store (campsaver) and chucked a new compass in as well. but at home it seems to point in a different direction to what i thought was north. google seems to think this is true but it is the first i have heard of it??

your advice is much appreciated!!

- dan

[MJD]

Your compass will point magnetic north as opposed to true north.

I found the following in regards to northern and southern hemisphere compasses:

...there are northern-hemisphere and southern-hemisphere compasses. This is due to the fact that the magnetic field lines to which a compass needle aligns point into the earth at the north and south magnetic poles. This means that in the northern hemisphere, the north end of the needle is pulled downwards and so the south end is counter-weighted to balance the needle. Therefore, when you use a northern hemisphere compass in, say Australia, the south end of the magnet is pulled downwards by the magnetic field and is also heavier than the north end - resulting in a needle that catches and drags on the bottom of the compass housing when the compass is held horizontal.

[dannnnn]

yup i was aware about magnetic north vs true north

from what you've posted it looks like the compass will 'stick'.. but to me it seems like that is something that can easily be overcome just by adjusting how you hold the compass?? i will be using it walking rather than on a perfectly flat desk so i don't see it sticking being a huge problem?? plus it is liquid filled so it's not like it is a high-friction environment anyway??

if it makes a difference, this is the compass here..

http://store.bruntonoutdoor.com/navigat ... ate/9020g/

i'm amused - such a strange thing to find out!!

[Orion]

A previous discussion on this topic: http://bushwalk.com/forum/viewtopic.php?f=15&t=1258

And if you're looking for a lightweight compass: http://bushwalk.com/forum/viewtopic.php?f=35&t=5551

[dannnnn]

thanks for your reply orion, the FAQ answers it very nicely

incidently brunton replied very quickly to an email i sent them.. here it is

Hi Dan,

Since your compass was purchased here in the US, it is most likely one balanced for the Northerly zone 1 which covers N.America, Europe and most of Asia. However, when taking a compass with that balance to the Southerly zone 3, you will experience needle 'dip' where one end of the needle will drag along the top housing of the compass.

You could theoretically just hold the compass at a slight angle where the needle swing freely, but this can result in some inaccurate readings.

Please let me know any further questions.

Best,

BRUNTON OUTDOOR
GROUP

Ryan Perry, Associate Product Manager

[durks]

from what you've posted it looks like the compass will 'stick'.. but to me it seems like that is something that can easily be overcome just by adjusting how you hold the compass??!

That generally works well enough - *until* a bubble develops in the liquid-filled housing of the compass (which often happens with age, or as a result of air pressure changes.) When that happens, the combination of having to tilt the compass in order to 'unstick' the needle, along with the bubble disturbing the needle, makes the whole business tedious and error-prone. And you don't want that when you're trying to navigate in earnest.

[photohiker]

The whole thing about using a northern hemisphere compass in the southern hemisphere is that it it a total PIA. Ok if its the only one you've got and you have no option, but if you have the choice just get one for the hemisphere you're in.

[rucksack]

I'm with Michael. Just buy a Zone 5 compass (that's balanced for Australia), or a global compass such as a Silva Voyager 8010, or a Suunto M-3 Global, which work in all zones and forget the 'tilting'. As I said in an earlier thread, you can read more about this at http://www.labsafety.com/refinfo/ezfacts/ezf313.htm or http://www.mapworld.co.nz/global.html or Google 'compass zones' or 'global compasses' for a more detailed explanation and to see the zones.

rucksack