Originally Posted by DRFerron
Your variation depends on which side of the country you are on. In the U.S., for me, it will be west. For the west coast (and west of the isogonic line) it will be east.
But yes, you are correct. Magnetic to true you subtract westerly variation and add easterly variation.
The examples I'm looking at show the compass rose of a chart with the variance noted in the center. I was hoping that following the rule of add east, subtract west will work on any chart.
Another question; When the rose has an inner magnetic rose, it is drawn to the variance noted in the center for that year, right? If the chart is older and the variance over the years was great enough to change the degree variance, I'll still have to allow for that if I use the inner magnetic rose.
Thanks for the response by the way.
Edit: And I guess I reverse the rule when converting from true to magnetic?