Can this GPS be used with some kind of serial usb converter, and is there any special drivers or anything like that to make this work. I have not bought the software yet, just trying to figure out the best setup, and I already have the GPS unit mentioned above.
Also what is the difference between the MacENC and the GPS NavX
You will need to connect the cable mentioned above to your GP31's power/data cable. The wiring diagram can be found in Fig. 7-20 on page 7-10 of the GP31 users manual:
GP31 manual
Use Data 2 RS232 Level output (see page 9-3).
The Keyspan USB to Serial cable can be found here:
Keyspan
(Alternatively, you can solder a Dsub 9 pin connector directly to the power/data cable wires if you like.)
And if you plan to add more instruments down the road, it might make more sense to use a Miniplex lite which you can connect the Furuno and other instruments (i.e. wind, depth, AIS) to (up to three NMEA inputs and one output) ..
http://www.shipmodul.com/en/miniplex-lite.html