Ships GPS Lat/Lon were not updating on the WF datamanagement system in the control room.  Serial Datastream was making it to the navprocessor (itchy) from the Leica GPS unit. The problem is that the system is coded to look for $GPGGA messages. (We need $GGA for datafields like DifferentialMode, HDOP etc).  The only data coming down the line were $ZDA and $GLL messages, even though $GGA was enabled on the Leica menu ( for serial port 9).  Dan Chamberlain tried cycling on/off the messages and discovered that turning off $DTM messages also turned off $GGA messages even though the menu reported $GGA was enabled.  (Seems to me to indicate a bug in the Leica code)

Anyway, next time.... Remember that if GPS ever dies in coredata logging, as indicated by dataprobe. This may be the issue.