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Navigation & chartwork

What is 'variation' in compass work?

Short answer

The difference between True North and Magnetic North

Variation is the angular difference between true and magnetic north. Obtain it for the charted place and date, update any stated annual change, and keep its east or west sign separate from vessel deviation.

Sources and scope

Reviewed by Richard Moore on . This answer is scoped to united kingdom and general recreational seamanship; check the current chart, publication, local rules and official operational guidance before acting afloat.

Quick check

What is 'variation' in compass work?