Chart Navigation & Plotting · Compass — Deviation by Range
Two charted objects in line (a range) bear 270°T. As you cross the range, your compass reads 274°. Variation in the area is 0°. What is the deviation on this heading?
- A4°W✓ Correct
- B4°E
- C0°
- D2°W
Explanation
A natural or charted range gives a known true bearing. With zero variation, magnetic equals true (270°). The compass reads 274°, which is 4° greater than magnetic; when the compass reads more than magnetic, the deviation is west. Deviation = 4°W. (Compass best, error west.)
Authority: Bowditch (Pub. No. 9), Deviation by Ranges
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