Raytheon Pathfinder ECDIS Operator's Manual page 213

7.1.4 Dead Reckoning
The Dead Reckoning feature serves two purposes:
It is a means to calculate your position from the available speed and heading
values, if your navigation device(s) fails;
It allows you to demonstrate or practice using ECDIS by simulation ship's
motion.
In order to simulate ship's motion with dead reckoning, you must select Dead
Reckon as an available "Navigation device", see chapter 7.1.2.
During Dead Reckon mode, you can select whether or not ECDIS will use the
heading from the GYRO and the bottom track speed from the speed log. If the
devices are available, you can select the "Get from Nav Device" check boxes for
the course and/or the speed. If ECDIS receives a valid reading while these
check boxes are checked, it will adjust the vessel accordingly.
ECDIS switches automatically to Dead Reckon if the selected positioning device
fails, as long as the Gyro and Speed Log are active. When it switches, an alarm
sounds, autopilot track control is turned off (if it was on), and a mark appears on
the ship's track with the time that dead reckoning stared. ECDIS will simulate
ship's motion using the bearing from the Gyro and the speed from the Doppler
Log. If another available navigation position device is selected, ECDIS will not
resume track control (Steer to Track) automatically.
Edition: 30.MAR.2007
ECDIS
Operator Manual
7−7
R
Raytheon Anschütz GmbH
Germany
3655DOC020102