USCG Exam PracticePlotting with variation and deviation (T-V-M-D-C)
Deviation differs from variation in that deviation is caused by which of the following?
- A. The geographic position of the vessel relative to the magnetic pole
- ✓ The vessel's own magnetism and changes with the vessel's headingCorrect
- C. The annual rate of change of the earth's magnetic field
- D. The difference between grid north and true north
Why B is correct
Deviation is caused by the vessel's own magnetism and changes with the vessel's heading; it is read from the deviation card. Variation, by contrast, depends on geographic position and changes slowly over time.
Cited:Bowditch Ch. 6 §601