Furuno FAR-28x7 Series - Manual (Page 176)

4. AIS OPERATION
4-12
4.9 Past Position Display
The past position display shows equally time-spaced dots marking past positions
of activated AIS targets. A new dot is added at preset time intervals until the
preset number is reached. If a target changes its speed, the spacing will be
uneven. If it changes course, its plotted course will not be a straight line.
Note that AIS past positions will be shown if TARGET TRACK on the DISPLAY
sub menu of the PLOTTER menu is ON, regardless of whether AUTO TARGET
TRACK on the PLOTTER menu is turned ON or OFF.
Below are sample past position displays.
(a) Ship turning (b) Ship running
straight (c) Ship reduced
speed (d) Ship increased
speed
Sample past position displays
4.9.1 Displaying and erasing past position points, choosing past
position plot interval
1. Roll the trackball to choose the PAST POSN box at the right side of the
screen.
PAST POSN REL 2MIN
PAST POSN box
2. Push the left button to choose plot interval desired: OFF, 30 s, 1, 2, 3 or 6
min. Choose OFF to erase all past position points and turn off the past
position display.