What does "dead reckoning" refer to in navigation?

Dead reckoning is a navigation method that estimates a vessel's current position based on its last known position, combined with calculations of speed, direction, and time traveled since that point. This approach involves keeping track of the movements and adjustments made while navigating, effectively projecting the path forward from a known position to arrive at an estimated current location.

The process is critical in scenarios where the navigator may not have a visual reference or external navigational aids, allowing them to maintain course when using instruments or during conditions with limited visibility. Dead reckoning incorporates ongoing updates of speed and course, which rely on navigational skills and calculations. This technique is foundational for piloting aircraft as well as for maritime and terrestrial navigation, especially in areas where GPS signals may be weak or unavailable.