The difference in degrees between true north and magnetic north is referred to as what?

The term that describes the difference in degrees between true north and magnetic north is known as variation. This is an important concept in navigation and maritime practices because it reflects how the Earth's magnetic field differs from the geographic coordinate system, represented by true north. Variation can change based on geographic location, which is essential for navigators to account for when using magnetic compasses to ensure accurate course plotting.

Deviation refers specifically to the error induced in a compass reading caused by local magnetic fields, such as those from the ship's metal structure or electronic equipment. Drift typically refers to the movement of a vessel due to wind or current, not a navigational error in terms of directional reference. Compass error generally encompasses any discrepancy in a compass reading, but it is a broader term that can include both variation and deviation as components. Understanding variation helps navigators adjust their bearings correctly for accurate navigation.