You sight Bartlett Reef Light in range with...

Question 1 of 2707066636eea28f7522a1c51b556

You sight Bartlett Reef Light in range with New London Harbor Light bearing 038°pgc. At the time of the bearing, the helmsman reports he was heading 253°pgc and 269° per standard magnetic compass. What is the deviation for that heading?

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Question 1 of 27070

🔍 Key Concepts

• Relationship between per gyro compass (pgc), standard magnetic compass, variation, and deviation • How to interpret a range (two lights in line) to find your true heading/course • Standard compass error formula: "Error = True - Compass" and how to separate variation and deviation

💭 Think About

• From the range, what can you say about your true course at the moment of the bearing? How does that relate to the reported gyro heading (pgc)? • Once you know the error between true and standard compass, how can you separate that error into variation + deviation? • Is the resulting deviation east or west if the standard compass reading is greater or less than the true heading?

✅ Before You Answer

• Confirm the true bearing/course when the two lights are exactly in range (lined up) • Carefully apply the sign convention: East is least, West is best when converting between True, Magnetic, and Compass • Verify that you are using the correct heading (the standard magnetic compass heading, not the gyro**) for the final deviation calculation