Chart Navigation & Plotting · Compass Conversion — TVMDC

True course 090°, variation 10°W, deviation 2°E. The compass course to steer is:

Explanation

Going from true to compass, apply westerly errors by adding. True 090 + 10W variation = magnetic 100; deviation 2E is subtracted = compass 098°. (Mnemonic: 'True Virgins Make Dull Companions, Add Whiskey' — add West when going down the column.)

Authority: Bowditch (Pub. No. 9); Dutton's Nautical Navigation

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