You sight Bartlett Reef Light in line with New London Harbor Light bearing 043°pgc. You are heading 088°pgc and 098.5° per standard magnetic compass at the time of the observation. Which statement is TRUE?
• Compass error is the difference between true and compass directions • Relationship between gyro heading, magnetic heading, and compass heading • How to derive variation and deviation from an observed bearing and heading
• How can you use the observed bearing of the range (043°pgc) and your gyro heading (088°pgc) to find the gyro error? Think about what that range line’s true bearing must be. • Once you know the true bearing of the range, how can you compare it with the magnetic compass reading (098.5°) to determine total compass error? • After you have total compass error, how do you separate it into variation and deviation, given that gyro is (ideally) referenced to true?
• Be clear on the sign convention: E errors are added, W errors are subtracted when moving between true, magnetic, and compass. • Verify that you are using the same reference (true) when comparing gyro and magnetic/compass values. • Double‑check that any stated deviation is the difference between magnetic heading and compass heading, not between true and compass.
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