Right, a couple of slow steady circles will calibrate the internals. Alternately, if you have an iPhone there's an included compas function which I have found to be surprisingly accurate.
John & Diane, fulltiming since '12 02 DS40, FL, Cat, '04 Element NHSO RVM103
John and Diane (RIP Lincoln, 21 FEB 22) RVM103 NHSO
Fulltimers since June, 2012
2002 Dutch Star 40, Freightliner, Cat 3126, 2004 Element