Simrad AP25 - Manual (Page 39)

Operation
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2.16 Navigating with the AP25
Note ! The source when operating in NAV mode is the Navigation (Nav)
source.
The AP25 has the capability to use steering information from an
external navigator (GPS, Chart Plotter) to direct the boat to a
specific waypoint location, or through a route of waypoints. In
the NAV mode, the AP25 uses the compass as heading source
for course keeping. The information received from the navigator
alters the set course to keep the boat on the track line and direct
the AP25 to the destination waypoint.
Note ! Navigational steering should only be used in open waters. By
selecting the NAV mode, the AP25 is set for automatic steering
on the current set course and then waits for the user to accept
the course change to the track line or destination waypoint.
To obtain satisfactory navigation steering, the following points
must be fulfilled prior to entering the NAV mode:
• The AP25 autosteering must be tested and determined
satisfactory.
• The navigation receiver (GPS, Chart Plotter) must be in full
operating mode with adequate signal characteristics for valid
position and navigation data.
• At least one waypoint must be entered and selected as the
current “Go to” waypoint.
• The navigation receiver (source) for the autopilot will be the
one that is automatically selected in the interface set-up or
manually selected in the User setup2 menu item called
“Source select” (page 52).
The AP25 is designed to steer in “mixed mode” operation. This
combines the straight steering capability of cross track error
(XTE) steering in conjunction with the turning capability of
bearing mode steering (Course To Steer, CTS) and automatic
Waypoint shift.
Note ! If the AP25 is connected to a navigation receiver that does not
transmit a message with bearing to next waypoint, it will pick a
XTE message and steer on Cross Track Error only. In that case
you have to revert to AUTO mode at each waypoint and
manually change set course to equal bearing to next waypoint
and then select NAV mode again.
Press the NAV button to activate the NAV prompt display.