Marc has it nailed-- you need both. NMEA 2000 connects all the items on the boat to pass data for display or control. Ethernet is like connecting 2 or more computers in a network so each can see the other. Bluetooth is for disconnected items such as a Mobile Controller or your phone. WiFi connects to the internet so you can download new software updates. You need them all for different things and your Ghost and HDS setup has them all.
