Funny... I've been working at the same job, testing electronic compasses (magnetometers) for 6 years and haven't ever had to re-align our compasses to magnetic north. (San Jose CA area.)

Also... People using our sensors have a correction factor that they can enter to compensate for the MAGNETIC DECLINATION (which is the difference in degrees between true and magnetic north). I suppose you could look up past Magnetic Declinations and see how much it has changed. Though we would have certainly noticed it by now.

So what's all the fuss about? Can someone show me some real data?

I suppose that Mag. N. has drifted 10 deg. over 30-40 years. But nobody mentions the time frame.


PR