RE: Furuno model 1720 radar unit.
Sure. You may have to select an older NMEA version than the Garmin provides by default. Usually under menu, options, NMEA or something like that. Just start with the default and work your way backwards if the first one doesn't work. Another problem is the cable to connect them... can you get one, or will you have to make one up? If the latter, you'll need the pin-outs and ins for the two pieces of equipment.