Variation
Variation is the angular difference between True North and Magnetic North. It changes slowly over time and varies by location. On a chart, variation is printed on the compass rose — for example: 'Var 2°W (2020)' means that Magnetic North is 2° west of True North, and this was correct in 2020.
The annual rate of change is also given (e.g., 'decreasing 8' annually'), so you can calculate the current variation. In UK waters, variation is typically around 1–3° West.
Key Points
- Variation = difference between True North and Magnetic North
- Found on the chart compass rose with date and annual change
- UK waters: typically 1–3° West (slowly decreasing)
- Apply variation to convert between True and Magnetic bearings