Your vessel is proceeding up a channel, and...

Your vessel is proceeding up a channel, and...

Question 1 of 2921866636ee928f7522a1c51a633

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 147°T, and the variation is 5°E. If the heading of your vessel at the time of the sighting is 148° per standard magnetic compass, what is the correct deviation?

Question 1 of 29218

Q

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 147°T, and the variation is 5°E. If the heading of your vessel at the time of the sighting is 148° per standard magnetic compass, what is the correct deviation?

🔍 Key Concepts

• True–Magnetic–Compass (T–V–M–D–C) relationship (often remembered as a TVMDC memory aid) • Effect of easterly variation on converting between true and magnetic • Difference between magnetic heading and compass heading gives deviation

💭 Think About

• Start from the charted range bearing (147°T). How do you apply a 5°E variation to convert that true bearing to a magnetic bearing? Think carefully about whether you add or subtract an easterly variation. • Once you have the magnetic bearing of the range, compare it with the heading by standard magnetic compass (148°). Is the compass reading more east or more west than the magnetic? • From that comparison, decide whether the deviation is easterly or westerly, and how many degrees apart they are.

✅ Before You Answer

• Be sure whether easterly variation is added or subtracted when going from true to magnetic. • Confirm you are comparing magnetic heading vs. compass heading, not true vs. compass directly. • Double-check the sign (E or W) based on whether the compass reads higher or lower than the magnetic value.