Compass Rose

A circular diagram on nautical charts and compasses that displays directions relative to true north and magnetic north, often including information about magnetic variation.

A compass rose is a navigational tool printed on nautical charts and instruments, showing the orientation of cardinal directions—north, east, south, and west—as well as intermediate points. It typically consists of two concentric circles: the outer circle indicates true directions based on geographic north (true north), while the inner circle shows magnetic directions aligned with magnetic north. The difference between these two, known as magnetic variation or declination, is usually noted near the compass rose in degrees east or west. This variation changes over time and location, so the chart also includes the annual rate of change to help navigators adjust their compass readings accurately. The compass rose assists mariners in plotting courses and bearings, ensuring that headings account for the difference between magnetic and true north. On modern charts, multiple compass roses may be included to reflect local variations across the charted area. Accurate use of the compass rose is essential for safe and precise navigation.