Let's start from the beginning:
- connect your GPS and have a look at the output of
Did the device appear there and got recognized and assigned a port device?
- A) do you have gpsd installed? does it start when you connect the GPS?
if you don't have it installed yet, install xgps and a while after inserting the GPS, run it - until you get xgps showing the info, there's not much to do in OpenCPN
- B) if you for some reason don't want to use gpsd (you do want to use it), make sure it is NOT running before you try to start OpenCPN and connect it to the GPS port (which you will see in the dmesg output)
- If it still is a no go, we will need to have a look at the dmesg output, the end of your system log (tail -n 50 /var/log/syslog) after you inserted the GPS and OpenCPN log and configuration