Although the marine business of Navman which was sold to the Brunswick Group and then ultimately became part of the Navico Group, is no longer producing products, there are still a lot of boats with Navman Instruments and Fish Finders onboard.
As a general rule, most Navman products had an NMEA0183 output which was usually the White wire of the Power/Data cable. However, before purchasing or installing a Sonar Server, we recommend that you check your units manual to be sure that it has a suitable NMEA0183 output and which wire colour the NMEA Output is on.
Click here for a wiring diagram for the popular Navman Depth 3100 instrument.