Marine 3/C Practice Test

Dead Reckoning is estimating your current position by projecting forward from a known point using the course you steer, your speed, and the time elapsed since the last fix. Start from a known position, multiply speed by time to get the distance traveled, and plot that distance along the direction of travel to arrive at the estimated position. If you sailed at 8 knots on a 045-degree course for 2 hours, you’d estimate a position 16 nautical miles along that 045° line from the last fix. Over time, small errors from wind or current drift accumulate, so you update your estimate with new fixes or drift corrections to stay on target. This method relies on your own movement and timing to determine position, rather than measuring from celestial bodies or landmarks or by directly using external positioning instruments.