What does "deviation" mean in the context of a compass?

In the context of a compass, "deviation" refers specifically to the error that arises due to local magnetic fields and the influence of the ship's structure on the magnetic compass reading. This phenomenon occurs because nearby metallic objects, electrical equipment, and other magnetic influences can distort the direction in which the compass points, leading to inaccuracies in navigation.

Proper understanding of deviation is crucial for accurate navigation, as it can lead to significant navigational errors if not accounted for. Navigators must regularly calibrate their compasses and understand how internal influences may affect readings to ensure they are navigating safely and effectively.

The other choices focus on different concepts related to navigation; variation refers to the difference between true north and magnetic north due to geographic differences, wind resistance does not directly affect compass readings, and adjustments of navigational charts typically relate to updates based on standard observations rather than immediate compass errors.