Navigation General · Compass - Magnetic
Compass deviation differs from variation in that deviation:
- AIs the same on all headings
- BNever needs to be applied
- CIs published on the chart's compass rose
- DChanges with the vessel's heading, while variation depends only on geographic location✓ Correct
Explanation
Variation is shown on the chart's compass rose and depends on where you are on Earth (and the year). Deviation depends on the ship's heading because the vessel's magnetic field shifts relative to the compass as she swings, so it is tabulated per heading.
Authority: Bowditch (Pub. 9)
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