Navigation General · Variation
A chart compass rose shows '15° W (2020) annual increase 0.1°.' In 2025, the variation would be approximately:
- A14.5° W
- B15.5° W✓ Correct
- C15.0° W — annual change is negligible
- D14.0° W
Explanation
From 2020 to 2025 is 5 years. Annual increase of 0.1° × 5 = 0.5°. Starting at 15.0° W, adding 0.5° westerly gives 15.5° W in 2025.
Authority: Bowditch (Pub. 9)
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