NorthStar 957 Operator's Manual page 169

With good DGPS corrections, your 957 should provide better
than four-meter accuracy (repeatable and absolute) 95 percent
of the time. SOG readings should be accurate to 0.1 knot.
You can connect your 957 to your loran receiver (as long as
the loran has the appropriate NMEA 0183 output capability),
and display and navigate with real-time loran TDs. With this
configuration, you'll keep the repeatable accuracy of your
loran, but will add all of the navigation features of the 957,
including the worldwide absolute accuracy of GPS.
957 Operator's Manual, Rev. B Page 161