Gyro error greater than how many degrees needs to be investigated?

• A. 0.5 degree
• B. 1 degree
• C. 2 degrees
• D. 0.1 degree

Answer: (B)

Gyro heading accuracy is crucial because the gyro provides the ship’s main reference for course. When the gyro error grows beyond one degree, it indicates the instrument’s alignment or drift has exceeded an acceptable limit and needs to be checked and corrected. That one-degree threshold is meaningful because even a small error can produce noticeable drift over time. For example, at a typical speed like 15 knots, a one-degree heading error can cause about 0.26 nautical miles of drift per hour; over several hours, the discrepancy between the indicated course and the actual path can become significant, affecting navigation, plotting, and collision avoidance. The limit is set to ensure reliable heading information without overreacting to minor fluctuations. Smaller errors would usually be within normal tolerance, while larger errors would allow dangerous deviations before action is taken. So, the correct threshold to investigate is one degree.