using a two year old Navtronic chart on a Raymarine chart-plotter/radar. The only electronic chartploter on board that auto updates is Coastal Explorer on my PC.
That experience two summers ago lead me to invest in the update program offered by Navtronics which required a trade in chip (from Defender) and gave me the ability to update for a year, but that required physically taking the chip out of the unit and updating via my PC when I had a good wifi connection. I took the chip home and did it all though the winter so I had a fresh chart at the beginning of last summers cruise.