I have been there. It was worse, I also had that gps300 thing or however they called it. Cost me a couple years of my life.
The only cure is to become firm and demand compatibility with NMEA2000. I believe Seatalk-ng is NMEA2000 with another connector but basically compatible without converters.
Then, install a standard NMEA2000 network with sensors for depth/log/water-temp, heading/heel/pitch, GPS, wind
speed/direction/air temp, humidity, barometer. Most find that this can be done with 4 sensors from Maretron plus their cabling components. Now just hook up your plotter, autopilot
etc. and you're done and past all the trouble.
Ah, takes compatible displays in the cockpit