In order to have the ability to network units, you need to look at the 700 series Humminbirds and above. If you decide to network using ethernet, you will need to purchase one of the newer "HD" models that will have ethernet capability. One other note, the 700 series (IE:788ci HD 788ci HD DI and 798ci HD SI) require an additional adapter cable (AS EC QDE)
* You can also share waypoints via Interlink for these same units.
Brian