Where exactly is the computer going to be located? If you're just going to put it somewhere in the cabin
and use it for planning purposes, pretty much any old computer will do. Running plotting software really isn't that resource intensive.
If you're wanting to use it for navigation
underway and have it on deck
, you're going to want a ruggedized laptop with a high brightness (~1000 nit) sunlight readable display. These are thousands of dollars, though.
As a halfway, you might consider keeping the laptop inside and then running a video cable to a waterproof monitor
for navigation purposes. You can get monitors like this with touchscreen input for 1-2 thousand.
Personally, I'm running Polarview on an old Macbook. If the conditions are rough enough that it would get soaked in the cockpit
, I'm probably not out on the water
. I like Polarview mostly because of the ease that it displays vector charts
and the fact that it has a chart downloader/updater built in. In your case, it also has a decent set of gauges that can be interfaced with NMEA through PolarCOM.
If you are alright using Raster charts
, you might consider OpenCPN
. I don't think it does gauges, though.