Application of variation 2

On every nautical chart there is at least one Compass Rose.
The Compass Rose consists of the following: the outer rose, which is aligned with the True North and the inner rose, which is aligned to Magnetic North.
Near the center of the Compass Rose we can read the local variation, the year that the variation was observed and the annual rate of change.
When we are shaping a course or plotting a position we need to convert between True and Magnetic.