"Terry Spragg" wrote in message
....
It matters, but a southern hemisphere compass? Yuk, yuk, yuk!


Come on Terry, you're not supposed to make jaxie look smart.

Compasses do indeed need to be adjusted for the Southern Hemisphere. Here's the
Ritchie comment:
http://www.ritchienavigation.com/ser...albalance.html

here's the actual map of inclination (known to mariners as "dip")
http://www.ngdc.noaa.gov/seg/geomag/icons/wmm2000i.gif
As you can see, there's a serious difference between the USA and New Zealand - plenty
to make the card jam if not balance properly.

Everything you might want to know about the Earth's magnetism:
http://www.ngdc.noaa.gov/seg/geomag/geomag.shtml