What does the Humminbird NEMA module do other than give you a neat graphic of engine conditions and fuel levels? I have a Humminbird system on my boat - 998 on a RAM by the console w a 788 in the bow and another 788 in the console. Am thinking of replacing the bow 788 with a 798. I saw the NMEA module on their website and downloaded the manual but can't figure out what it does.
