Compass error is equivalent to what?

Compass error refers to the difference between the direction indicated by the magnetic compass and the true direction of the geographic north. This difference arises from two key concepts: variation and deviation.

Variation, also known as magnetic declination, is the angle between true north and magnetic north. It changes depending on where you are located on the Earth. Deviation, on the other hand, refers to compass errors caused by local magnetic fields affecting the compass reading, typically due to metal objects or electrical equipment onboard a vessel.

When you combine variation and deviation, you obtain the total compass error. This means that by adding both the influences of variation (the steady discrepancy due to geographic location) and deviation (the local effects that can fluctuate), you can accurately determine the compass error. Thus, it encapsulates all factors impacting the compass reading, leading to the correct understanding of how far the compass indicates compared to true north.