Which description best explains dead reckoning in navigation?

Which description best explains dead reckoning in navigation?

• A. Using GPS updates to determine position.
• B. Relying on depth readings to estimate location.
• C. Determining position from wind speed alone.
• D. A position estimate based on course, speed, and time from a known fix when no precise fix is available.

Answer: (D)

Dead reckoning estimates your current position by starting from a known point and projecting ahead using your course and speed over the elapsed time. It converts speed into distance traveled and plots that distance along the reported course from the last known position, giving a position estimate when no precise location fix is available. This approach relies on your own motion data rather than external position signals, and it naturally accumulates small errors over time, which is why ships routinely recheck with actual fixes when possible. That description matches the idea of a position estimate based on course, speed, and time from a known fix when no precise fix is available. Other methods depend on external fixes like GPS or use measurements (depth, wind alone) that don’t directly yield a current horizontal position.

Dead reckoning estimates your current position by starting from a known point and projecting ahead using your course and speed over the elapsed time. It converts speed into distance traveled and plots that distance along the reported course from the last known position, giving a position estimate when no precise location fix is available. This approach relies on your own motion data rather than external position signals, and it naturally accumulates small errors over time, which is why ships routinely recheck with actual fixes when possible. That description matches the idea of a position estimate based on course, speed, and time from a known fix when no precise fix is available. Other methods depend on external fixes like GPS or use measurements (depth, wind alone) that don’t directly yield a current horizontal position.