Navigation General · Variation
Magnetic variation is defined as:
- AThe angular difference between the compass needle direction and magnetic north, caused by the ship's metal
- BThe angular difference between true north and magnetic north at a given location✓ Correct
- CThe daily change in compass heading due to solar wind
- DThe error introduced by compass card friction
Explanation
Variation (also called declination) is the angle between true north and magnetic north at a given geographic location. It is shown on the chart compass rose and changes with position and slowly with time.
Authority: Bowditch (Pub. 9)
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