[guywhocodes]

You can interpolate the GFS very accurately in terms of wind over land and close to land with WRF-ARW. There is highish resolution land use data and good elevation models. This is something you can do on your laptop even these days.

However I have no idea of good it is at wave and currents.

[repsilat]

You can also put the compute and the data on land, and do routing as a service. The decision bandwidth (i.e., ideal heading/route) is miniscule.