Akita :

Does anybody has any experience with Linux software for sailing?

I don't know of any specifically marine navigation software for Unix. You
might try gpsdrive, but I doubt it will be satisfactory. The fundamental
problem is to find free maps*: most maps are distributed in closed or
encrypted formats, requiring NDAs from the software writers, which is
incompatible with open-source development (the only exception I know of is
the american charts, available from
http://nauticalcharts.noaa.gov/mcd/enc/download.htm). As long as we are
stuck with these formats, there is not much point in writing a navigation
system.