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 064°T, and the variation is 17°W. If the heading of your vessel at the time of the sighting is 094° 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 064&deg;T, and the variation is 17&deg;W. If the heading of your vessel at the time of the sighting is 094&deg; per standard magnetic compass, what is the correct deviation?

Accepted Answer

Option D: 13&deg;W. Compass error is the difference between true and compass headings. With a true heading of 064 degrees and a magnetic compass heading of 094 degrees, the total error is 30 degrees West. Subtracting the 17 degrees West variation from the 30 degrees West total error results in 13 degrees West deviation.