Dead reckoning

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Cutlery relocation

Dead reckoning or coupling ( coupling , connecting ), engl. Dead reckoning is the ongoing approximation of the location of a moving object based on the direction of movement ( course ) and speed ( travel ).


The course is measured with the compass , the ship's speed is measured with the log , the airspeed with the airspeed indicator . These instruments determine the speed only relative to the surrounding medium water or air. In addition, loads for movement by electricity and wind must be attached in order to be able to calculate or estimate the speed and course over the ground.

In combination with precise clocks, a gyro compass and speedometers, partial automation of the coupling and the display of the position on an automatic coupling table became possible from 1909 .

Under favorable conditions, the measurement error when coupling is less than 5% of the distance. As soon as possible, a new starting point for the further coupling is determined, for example with the aid of astronomical navigation or, more recently, by radio navigation means .

As cutlery displacement (BV), also cutlery offset is called the vector from Loggeort (O g , and O k for dead reckoned) to the established for the same time, true location (O w and O b for the observed site). The amount of cutlery being moved is given as a measured distance in nautical miles , and its direction is given in compass degrees.

In visual flight , the rather coarse dead reckoning is also called "Franzen" in aviator language (named after the nickname for the navigator - "Franz" - who could sometimes "get lost" ).

To automate and increase accuracy - especially for flight navigation - new methods such as Doppler navigation (radar antennas with Doppler effect) and inertial navigation have been developed in recent decades . They now allow on-board accuracies in the range of 1 ‰ of the distance covered and are now part of integrated navigation .


A vivid example of dead reckoning can be found in the film The Hunt for Red October . In one scene, the eponymous submarine is navigated through a system of submarine canyons by precisely timing the necessary course changes using a precise map with the help of a stopwatch.


  • Karl Terheyden (ed.): J. Müller, J. Krauss - Handbuch für die Schiffsführung , Volume 1, Navigation, Part A. Springer Verlag, Berlin 1983. ISBN 3-540-10889-0 .
  • Heinz Kärsten: Nautical paperback . Fachbuchverlag Leipzig, 235 pp., 153 ills. 1955.
  • Winfried Boehm: Manual of the navigation. Bussesche Verlagshandlung GmbH, Herford, 246 S. 1978, ISBN 3-87120-323-8 .
  • Niels Klußmann, Arnim Malik: Aviation Lexicon. Springer, Berlin 2007. ISBN 978-3540490951 .


  1. formerly cast place, cast cutlery