Hello I'm in need of some serious answers if anybody can help me, I own a four winns sl 242 with a mercruiser 8.2 big block with dts and smart tow with rpm cruise control. I have upgraded it with 2 lowrance carbon hds and a mercruiser vessel view link all on a nmea 2k network. I can now have gps speed on my digital instruments but when I switch it from rpm to gps on my cruise control it doesn't work 
I've spent hours online and on the phone to find out why or why not with no answers, the only info I can come across myself is that the smart tow pro has a gps puck built into the gauge where my smart tow gauge and vessel view link doesnt and although the vessel view link sees a gps speed reading from the lowrance carbons its not telling the engine the info to hold that speed. I dont really want to get another gauge if I dont have to, would a additional gps on the nmea 2k network work?? Or the engine needs the smart tow pro level 3 gauge to see a gps signal for its cruise control PLEASE HELP!!!
I've spent hours online and on the phone to find out why or why not with no answers, the only info I can come across myself is that the smart tow pro has a gps puck built into the gauge where my smart tow gauge and vessel view link doesnt and although the vessel view link sees a gps speed reading from the lowrance carbons its not telling the engine the info to hold that speed. I dont really want to get another gauge if I dont have to, would a additional gps on the nmea 2k network work?? Or the engine needs the smart tow pro level 3 gauge to see a gps signal for its cruise control PLEASE HELP!!!