I've been working on a sailing navigation simulator, using real-world geographical and real-time weather/ocean data: https://8bitbyte.ca/sailnavsim/

Both the core simulator [0] and geographical/weather/ocean data handling library [1] I wrote are free and open source, in case it might benefit anyone else, or if they're interested and would like to contribute. :)

[0] https://github.com/ls4096/sailnavsim-core

[1] https://github.com/ls4096/libproteus