Chart Navigation & Plotting · Compass Error
You observe a range (two charted objects in line) bearing 270° true. Your magnetic compass reads the range as 263°. With variation of 4°E, the deviation on this heading is:
- A3°E✓ Correct
- B11°W
- C3°W
- D7°E
Explanation
Compass error = true − compass = 270 − 263 = 7°E (compass reads low, so error is East). Compass error = variation + deviation, so deviation = 7°E − 4°E = 3°E.
Authority: Bowditch, American Practical Navigator (Pub. 9), compass checks
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