Quote:
Originally Posted by jman17
Hi,
I think I am getting the idea. I live in Toowoomba so would point the unit to 169.47 degrees.
jman17
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Depends what you mean by "the unit."
If you are referring to the polar axis & you point the polar axis at 169.5 magnetic bearing you will be off by 21 degrees. Jimmy's instructions are correct but need to be read very carefully.
There are two ways to use a compass, be it a magnetic compass or an ipad app. Both ways illustrated below indicate true south. The one on the left is much easier to use. Get the north compass needle to point to 10.5 or the south needle to point to 190.5 (10.5 is the magnetic declination for Toowoomba). Then the N & S dial indicators on the compass protractor and the edge of the compass/iPad all point north/south. You can use the method on the left in which case, yes, point the polar axis at 169.5.
If you are using iPad that has GPS, I'd suggest using an app called Spyglass. You can adjust the settings so that it performs the magnetic dec correction automatically and displays true bearings. It also uses the camera and superimposes the compass on the camera image. Works a treat.
This page has an AGRF calculator for any location and explanations of the sense of D with examples.
http://www.ga.gov.au/oracle/geomag/agrfform.jsp
Joe