Why was dead reckoning important to early navigators?

Dead reckoning was a vital navigational technique for early explorers because it allowed them to determine their position by tracking their course and distance from a known starting point, independent of celestial observations. By using a compass to maintain a heading and a log to estimate speed, navigators could plot their current location and project their future path.12

This method was essential for planning entire journeys, including estimating arrival times at a destination. In fields like hydrographic surveying, it provided a necessary framework for mapping areas between established astronomical fixes.23

However, because dead reckoning relies on estimates, errors from factors like wind or ocean currents accumulate over time. Consequently, early navigators used it as a continuous estimation tool that was periodically corrected or "reinitialized" whenever a more reliable position could be determined through landmarks or celestial navigation. This process enabled consistent movement and planning across the open sea and air before the advent of modern electronic positioning systems.123