Originally Posted by 9D280
I would guess it's a bit like a remote switch version of the ones most plotters I've seen have - push the "MOB" button & it drops a "mob waypoint" on screen with an "auto goto" to provide a big arrow to point you at them.
That's pretty much it - the plotter has a switch input with the MOB button / MOB killcord at the 4th seat wired in series across it. Press the button on the console or pull the MOB killcord and the circuit breaks.
The plotter records the MOB position as current GPS position, and displays an MOB mark on the chart at the location. It also gives range and bearing back to the MOB, as well as time to get back to MOB at current speed and time the MOB has been in the water.