Magnetic Variance
I've been reading up on charts and how to plot bearings. The books I have all seem to describe converting magnetic bearings to true bearings in the same way and they have me confused.
I understand that the variance given in the compass rose has a stated variance, when it was measured, and the amount and direction of change per year. I understand how to find the current year variation from this information. What's confusing me is the statement "To convert a magnetic compass reading to true to plot on a chart *subtract a westerly variation *Add an easterly variation." Assuming that my variation after figuring for current year is 5* W. and forget deviation for a moment, let's say I take a compass bearing of 270*. Would my conversion be 270  5 = 265*T? If the variance was 5* E then the conversion would be 270 + 5 = 275*T? I'm not sure why I'm having so much trouble picturing this in my head. 
Re: Magnetic Variance
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. 
Re: Magnetic Variance
!!!Except in the Bermuda triangle! Or the superstition mountains, but you can't sail there.

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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? 
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They give you both east and west so that the publishers can use the same example on either coast. But you need to use the one that's applicable to your area. Quote:
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I hope this helps. A great book that I recommend is How to Read a Nautical Chart by Nigel Calder. Good explanations and it also contains all of Chart No. 1. 
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Well since no one's said it, and at the risk of outdated PCness, I'll repeat the jingles I learned back in Power Squadron and around the docks:
To get from From True to the Compass course to steer, you add Westerly error and subtract Easterly error. So, it's True, +  Variation = Magnetic, which +  Deviation = Compass (and you add Westerly error and subtract easterly error for both variation and deviation, so in shorthand it's: "TVMDCAdd W", (meaning True, Variation, Magnetic, Deviation, Compass, and add Westerly errors) How to remember?? as the old nonPC sailors said, "True Virgins Make Dull CompanionsAdd Whiskey" And to go the opposite way, from Compass to True, it's ("CDMVT, Add E") or the jingle" "Can Dead Men Vote TwiceAt Elections?" (here in Louisiana, of course the answer is yes, ha ha) There may be a more modern set of jingles, but True Virgins and Dead Men is what I grew up with, and I can remember the jingles when I can't remember the formulas. 
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