Dead Reckoning - Simrad SX90 - REFERENCE MANUAL REV D Reference Manual

Simrad SX90
122

Dead Reckoning

The
Dead Reckoning
button in the
Dead Reckoning
The
Dead Reckoning
the historical track line from the vessel, relative to the actual
position of the drifting fishing gear. In order to get correct dead
reckoning, a doppler speed log must be connected to the sonar.
When switched off, the vessel movement and track line will be
calculated from the GPS data, which then will be relative to the
bottom.
When switched on, the inputs from the gyro and speed log are
used to positioning the vessel relative to the water.
About Dead Reckoning
Dead reckoning is the process of estimating one's current
position based upon a previously determined position, or fix,
and advancing that position based upon measured velocity,
time, heading, as well as the effect of currents or wind. While
this method of navigation is no longer considered primary in
ships, it is still often used as a backup in case of failure of the
electronic navigation systems. Dead reckoning begins with a
known position, or fix. This fix is then advanced, mathematically,
by means of recorded heading, velocity, and time. The velocity is
determined by means of the doppler log.
Related topics
Setup menu on page 89
parameter dialog opens when you click the
menu.
Setup
function is used to improve the position of
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