Your vessel is proceeding up a channel, and you see a pair of range lights that are in line ahead. The chart indicates that the direction of this pair of lights is 186°T, and the variation is 11°W. If the heading of your vessel at the time of the sighting is 193° per standard magnetic compass, what is the correct deviation?

Question

Your vessel is proceeding up a channel, and you see a pair of range lights that are in line ahead. The chart indicates that the direction of this pair of lights is 186&deg;T, and the variation is 11&deg;W. If the heading of your vessel at the time of the sighting is 193&deg; per standard magnetic compass, what is the correct deviation?

Accepted Answer

Option A: 4&deg;E. True heading is 186°. Magnetic heading is True minus Variation (186 - (-11) = 197°M). With a compass heading of 193°C, the deviation is the difference between Magnetic and Compass. Since the compass reads lower than magnetic, the deviation is 4°E (Compass Least, Magnetic Best, Error East).