Do you think that players with the same version of the game could 'share' a patrol by emailing the saved mission file(s)?
I think it should be tested, to allow players to share the same boat, standing watch 'as it were' for an agreed number of hours per game day.
Then save and share out the saved game file(s) to all players who are sharing the patrol. I'd say four officers per patrol.
Each would take his turn at an agreed schedule and in sequence. The others would not play the mission until they (1) receive the latest saved file(s) and it is their turn. Any officer could look in at what is happening without saving anything. If it is getting dangerous, and not your duty, get out without saving.
Anyone up for a test?