🔍 Key Concepts

• Gyro error is the difference between the TRUE bearing and the GYRO bearing of the same object • Compass error (standard/steering compass) is the difference between the TRUE bearing and the COMPASS bearing of the same object • The relation between gyro heading, standard compass heading, and bearings taken at the same instant can tell you if each instrument is in error to the east or west

💭 Think About

• Compare the relative difference between the helmsman’s gyro course steered (pgc) and standard compass course (psc). Is the standard compass reading higher or lower than the gyro? By how many degrees? • Think about the object you lined up (North Dumpling and Latimer Reef Lights). That transit gives you a known TRUE line. How does the 075°pgc bearing relate to that true line if your gyro is in error? • Decide what it means in practice when we say an error is easterly or westerly. Does an easterly error make the indicated reading larger or smaller than the true value?

✅ Before You Answer

• Be clear on which instrument each symbol refers to: pgc = per gyro compass, psc = per standard (magnetic) compass • Check the sign convention: if the instrument reading is greater than the true bearing, is that considered an easterly or westerly error? Verify before choosing • Before picking an option, separately determine the likely gyro error and standard compass error (or deviation) and see which statement, if any, correctly matches both the magnitude and the direction (E/W)