Humminbird 778c 700 series Operation Manual page 89

When navigating, the following NMEA sentences are also output when
NMEA Output is turned On:
APB - Autopilot Sentence B
BWR - Bearing and Distance to Waypoint
RMB - Recommended Minimum Navigation Info
To turn NMEA Output on or off:
1. Make sure the User Mode is set to Advanced, then highlight NMEA
Output on the Setup main menu.
2. Press the LEFT or RIGHT Cursor keys to change the NMEA Output to On
or Off. (Off, On, Default = Off)
81 Setup Menu Tab