USCG Exam PracticeCompass variation and deviation; T-V-M-D-C
A vessel's true course is 090°. Variation is 8°W and deviation is 4°E. What compass course must the helmsman steer?
- ✓ 094°Correct
- B. 086°
- C. 098°
- D. 082°
Why A is correct
Working from true to compass (T-V-M-D-C in reverse): True 090° + 8°W variation = Magnetic 098°; Magnetic 098° – 4°E deviation = Compass 094°. When converting true to compass, westerly variation is added and easterly deviation is subtracted. 33 CFR §164.78(a)(5) requires the towing vessel operator to apply both corrections.
Cited:33 CFR §164.78