Best upgrade path is a 12
chartplotter. It does not have to be Raymarine but the Element series is definitely a good value option. You need a 12 because the new chartplotters are 16:9 (wider) vs. the C80 which is 4:3 (taller), 8.4 display. Thus, in order to get a similar size height for your new display, you need to jump a size.
Once you get your new 12 display, you will need to enlarge the housing to make it fit. You can do this with a dremel, it is a 30 min job.
It will have a built in
GPS, you may also consider interfacing with the
autopilot for heading data (essential in my book). In the future, you may add more integration if you feel like it.
SV Pizzazz