Why should variations on true bearings be checked regularly?

Regularly checking variations on true bearings is essential for ensuring accurate charting and navigation. True bearings are measured relative to true north, while magnetic bearings vary depending on the magnetic declination in a given area, which can change over time. As navigators rely on accurate bearings to determine their position and course, discrepancies can lead to navigational errors, potentially resulting in dangerous situations at sea.

By keeping track of variations and regularly adjusting for them, mariners can ensure that their navigational instruments are providing accurate readings. This accuracy is crucial for safe navigation, especially when navigating through congested areas or in adverse weather conditions where mistakes can have severe consequences. Thus, maintaining the integrity of navigational data is vital to the safety of the vessel, crew, and other maritime traffic.