You don't need the public Internet to run Moodle. It'll run perfectly happily on a local "intranet". Which, I assume, is what modern ships must have.
Your only restriction is that you will definitely need an "on board" server for Moodle. However, again, I suspect that this isn't going to be a huge issue as it will be the same for other systems.
Your only restriction is that you will definitely need an "on board" server for Moodle. However, again, I suspect that this isn't going to be a huge issue as it will be the same for other systems.