Coastal Navigation Practice Exam 2026 - Free Coastal Navigation Practice Questions and Study Guide

When magnetic variation can’t be verified, magnetic bearings can’t be trusted to tell your true heading or position, because the difference between magnetic north and true north is unknown. Relying on a magnetic bearing as the sole navigation reference would introduce an unquantified error into your course, and that error can lead you off track, especially in coastwise navigation where precise headings matter. The safer approach is to use true-heading information from non-magnetic sources (like a gyro heading, GPS, or celestial fixes) and cross-check with other references, rather than depend on magnetic bearings alone. Gyro headings, while useful, can drift and should be checked against other references. Ignoring bearings altogether isn’t practical for navigation.