What is "dead reckoning" in navigation?

Dead reckoning is a fundamental navigation technique that involves estimating one's current position based on a previously known position, factoring in speed, distance traveled, and direction over time. This method allows navigators to plot their course without relying on external references, which can be particularly useful when visibility is poor or when navigating in areas where landmark recognition is difficult.

The process starts with a known position, also referred to as a fix, and updates this position as the vessel moves. By determining the speed over ground and the heading, the navigator can project where the vessel should be after a certain duration. It is important to note that while dead reckoning provides a valuable means of estimating location, it can accumulate errors over time due to factors like changes in speed, drift from currents or tides, and wind effects, thus necessitating periodic fixes using other methods when possible.

This choice succinctly encapsulates the essence of dead reckoning, making it the correct answer. Other options, while relevant to navigation, address distinctly different methods or systems that do not define dead reckoning directly.