Iceberg said:true south is actually 180...hence true south
the magnetic deviation is only for a fixed system
PSB said:Point compass to south (Mag.) 180 deg.
Then refer to the below, add or subtract the (Mag. Dev.) value in your area from 180 and without moving the compass look and see where the true south will be.....
http://emantechnology.com/magnetdecln.htm
Remember this only gets you in the ball park in the sky, then use signal quality meter...