In navigation, dead reckoning is the process of calculating current position of some moving object by using a previously determined position, or fix, by using estimations of speed, heading direction and course over elapsed time.
A method of estimating the position of a ship or aircraft by applying estimates of the distance and direction travelled to a previously known position. In respect to ships/boats, it excludes the effect of wind and current on the vessel. Compare with estimated position. Abbreviation: DR.