I bought my compass in the US last year. Next week I'm going to travel to Australia.
- Is my US-compass compatible with Australia? or do I need a special compass?
- Do I need an adapter?
I double checked a couple of websites (thanks a lot for the comments to the question) and I'm sure that my compass is not compatible with Australia.
As a result of these magnetic variances, the compass industry has divided the earth into 5 "zones", as identified in the map which shows the different zones starting with Zone 1 at the top and ending with Zone 5 at the bottom (Australia and New Zealand only). All of the standard compasses sold at New Zealand are balanced for Zone 5.
A typical feature for regular compasses is that they can function without problems only at limited longitudes because the changes in the magnetic field affect the position of the needle. For fast needles, this phenomenon is even more prominent.
As well Wikipedia suggests that my compass is not working in Australia:
Because the Earth's magnetic field's inclination and intensity vary at different latitudes, compasses are often balanced during manufacture so that the dial or needle will be level, eliminating needle drag which can give inaccurate readings. Most manufacturers balance their compass needles for one of five zones, ranging from zone 1, covering most of the Northern Hemisphere, to zone 5 covering Australia and the southern oceans. This individual zone balancing prevents excessive dipping of one end of the needle which can cause the compass card to stick and give false readings.
Therefore the answer is:
Having used my Europe compass in America as well as in Australia, I would say you do not need a new one.
It will still point one end of the needle to the north and the other to the south, only the south pole is closer to you than when you are home.
As pointed out in the comments and the other answers, the direction as given is good enough for casual use, not for situations in which your life may depend on it. Hand held compasses are more likely suitable, mounted ones as in sailboats and planes may not work well enough.
While it is true that the magnetic field encompassing the Earth is not a sphere and dips inward at the poles, there is no reason a standard compass would not tell you which way is south and which way is north. While doing a google search for compass zones and which one to use for where, I got an astounding number of results for GPS calibration and pretty much nothing for standard analog compasses. There was one(1) sailing forum [www.cruisersforum.com] in which a user mentioned the need of "zoned" compasses for travelling below the equator. In one post. Thats it. If the need for "zoned" compasses were real, there would be a lot more information available on the internet.
If the worry is getting completely lost in the blue mountains or similar, I would think bringing a good map, gps, x-tra batt., compass, and a good working knowledge of orienteering would be paramount.
I have to agree with Willeke on this one, he's got experience. Both Sources given by the OP in his answer are from the same website, "mapworld.com" The wikipedia source cites mapworld as the source for that info. Mapworld is a RETAILER OF COMPASSES IN AUSTRALIA AND NEW ZEALAND.
The effect that might make a compass not work in two different regions of the world is called (magnetic) declination. This is due to geometry (geographical and magnetic north are not the same) and local effects on the worlds magnetic field.
A compass might be adjustable to this. Usually there is a little screw, with which you can turn the scale to adjust for the declination angle. Any decent regional map has this declination value marked on it or you can find it online.
For US and Australia the declination does not have to, but can vary a lot. This map showing the declination shows that the declination in the west of the US and in the east of Australia are pretty similar. So to answer the question whether you need a different compass you need to disclose the declination of your compass and more precise locations than US and Australia.
As far as I know there is no such thing as adapters for this. That would be something like an additional scale to mount on top of a compass - not very practical. But maybe someone had an ingenious idea and put it on the market proving me wrong in this - I doubt it.