Originally Posted by nolatom
Well since no one's said it, and at the risk of outdated PCness, I'll repeat the jingles I learned back in Power Squadron and around the docks: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.
