USCG Exam PracticePlotting with variation and deviation (T-V-M-D-C)
A vessel's chart shows a variation of 10°W. The compass deviation card shows 3°E for the vessel's current heading. What is the compass error, and in which direction?
- A. 13°W
- ✓ 7°WCorrect
- C. 7°E
- D. 13°E
Why B is correct
Compass error is the algebraic sum of variation and deviation. 10°W variation combined with 3°E deviation yields a net compass error of 7°W (10W − 3E = 7W). This application of variation and deviation is required under 33 CFR §164.78(a)(5).
Cited:33 CFR §164.78