Last night’s pub chat:
Will my compass (Silva, purchased in the local (UK) outdoor shop) work in Australia, or do I need a new one?

One guy who’d been to Australia, said it would not work. Everyone else said it would.

Hive mind to the forum please!

It’ll work but be 180 out

You need a S hemisphere one

Total george, It’ll work just as it will in the real world. But Variation can be huge in certain areas, NW especially.

It’ll work but be 180 out

You need a S hemisphere one

That must be very confusing for people on the equator. 😀

I don’t think it will work because iirc the needle is weighted on the southern end to conteract the magnetic pull of the north pole coming out of the ground. Go to Australia and it will be arse about face and the southern end of the needle will just drag on the base of the compass face.

So that’s why my oz flight lands in Bangkok,its to change the compass.

You need one with the needle magnetised the other way round, so it points South instead of North.

EDIT: apparently, they are made differently in the Southern hemisphere, due to the weighting thing above.

I’m guessing you could probably tilt it yourself to help the needle move more easily.

You need one with the needle magnetised the other way round, so it points South instead of North.

they print all their maps upside down in Australia too.

A compass doesn’t ‘point north’, that’s a lie to children, it’s inside a large magnetic field.

You’re going to have issues as you get near the Earth’s poles, but merely changing hemispheres won’t make a fig of difference. Your antipode friend was “coming the raw prawn” I believe.

I can sell you one when you get here don’t worry. There are also the drop bears to worry about….

I suspect your antipodean friend as a few kangaroos loose in his top paddock

Needles are weighted differently

You need one with the needle magnetised the other way round, so it points South instead of North.

South doesn’t magically reverse and become North when you cross the equator, any more than gravity suddenly starts working in the opposite direction.

South doesn’t magically reverse and become North when you cross the equator, any more than gravity suddenly starts working in the opposite direction.

Cougar, I was being sarcastic.. however I had to eat my words because there are in fact differences between NH and SH compasses.

A compass doesn’t ‘point north’, that’s a lie to children, it’s inside a large magnetic field.

You’re going to have issues as you get near the Earth’s poles, but merely changing hemispheres won’t make a fig of difference. Your antipode friend was “coming the raw prawn” I believe.

You’ve contradicted yourself nicely there.

Think about how the compas ‘sees’ the magnetic field, near the equator the field is almost parralel to the earths surface, near the poles the firld is near perpendicular. You can buy compases that have the magnet aligned so that it works best at a certain latitude.

If you buy an electronic compas it wil need calibrating if you move more than a hundred miles or so, usualy by placing it on a level surface and rotating it 360deg a number of times untill it’s worked out what angle the magnetic field is at.

It will work, but only if you stand on your head and hold it upside down.

True…

I was being sarcastic..

Sorry, out of coffee error. I did wonder!

there are in fact differences between NH and SH compasses.

Seemingly so. Enough of those words to share?

http://www.ngdc.noaa.gov/geomag/faqgeom.shtml

5c. What happens to my compass in the southern hemisphere?

For a compass to work properly, the compass needle must be free to rotate and align with the magnetic field. The difference between compasses designed to work in the northern and southern hemispheres is simply the location of the “balance”, a weight placed on the needle to ensure it remains in a horizontal plane and hence free to rotate. In the northern hemisphere, the magnetic field dips down into the Earth so the compass needle has a weight on the south end of the needle to keep the needle in the horizontal plane. In the southern hemisphere, the weight needs to be on the north end of the needle. If you did not change the weight, the needle would not rotate freely, and hence would not work properly.

You’ve contradicted yourself nicely there.

Think about how the compas ‘sees’ the magnetic field,

I was, just evidently not accurately enough.

Spinning freely here

Bigger problem is maps are a bit rubbish for some areas

Mine, a Silva, worked badly in South America: it was slow to respond. I never took it to Oz.

I half remember reading that they are made for the region where they are sold.

Bu@@er! – cancels order for STW stem cap compass…

No don’t panic! If you buy one of our Stem Captain compasses we will include an adaptor to mount it upside down in your fork crown if you are planning to cross the equator. It’s harder to read as you need to upend your bike and remove the front wheel but I promise it will work.

😉

Poor marketing there. You should surely be able to sell two….

but I promise it will work.

pop one in with my next mag and I’ll test it. At least a 12 word review for free!

What about the compass on an iPhone?

You need a global compass… recta and Suunto make them. Probably Silva too, but I’m not sure…

http://www.amazon.com/Suunto-SS004252010-MC-2G-Global-Compass/dp/B000FEUCRW

What about the compass on an iPhone?

I think you have to turn the battery around to weight the needle.

I believe you can adjust the compass using a left-handed screwdriver and a long weight.

Is it metric? I know an imperial one would.