I think a banana pi pro with a 7" touch screen
work well in the cockpit
. I am still working on the waterproof case design, but essentially you have banana pi pro + touchscreen + 12v->5v converter + USB gps
+ wireless keyboard mouse if you want it, with only 12V into the sealed case around the glass touchscreen. The screen
is powered off the pi. The OS is a dedicated debian configured like a 'kiosk' so you just power on 12V and it comes up running opencpn
with no keyboard or mouse interaction needed. It has wifi if you want a peer to peer network (or access point) and you can easily hook up rf24 radio
modems if you want to wirelessly bridge AIS
I like the 'dedicated kiosk' style because it eliminates fiddly bits and works like a regular boat accessory: On/Off from the main switch panel.
I anyone wants to try this I have 4G disk images
you can download and try on request. Also I wrote up more or less the steps to build it yourself on Debian Jessie also available upon request...