Chart Navigation & Plotting · Compass — Compass Error from Variation and Deviation
Variation is 7°E and deviation is 3°W on your present heading. What is the resulting compass error?
- A4°W
- B10°E
- C4°E✓ Correct
- D10°W
Explanation
Compass error is the algebraic sum of variation and deviation. Treat east as positive, west as negative: +7° (var E) + (−3°) (dev W) = +4°, i.e., 4°E. Compass error is applied to compass readings to obtain true.
Authority: Bowditch (Pub. No. 9), Compass Error
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