The Compass Rose
Each chart has one or more compass roses printed on it. The outer ring shows True North (aligned with the chart grid). The inner ring shows Magnetic North, offset by the local variation. The variation value and year are printed on the rose, along with the annual change.
When using parallel rulers, walk them to the compass rose and read bearings from the appropriate ring — the outer ring for True bearings, the inner ring for Magnetic bearings.
Key Points
- Outer ring = True North (chart grid)
- Inner ring = Magnetic North (offset by variation)
- Variation, date, and annual change printed on the rose
- Use the outer ring for True bearings in chartwork