As Gargamel says, I don't think it would be possible for two players to "play" the same u-boat unless they're sitting in front of the same open session of one game installation.
I guess it would be possible with something like PC Anywhere (is that still even a "thing"?) or something similar where another person connects to your computer and can see your desktop and open programs and interact with stuff that your PC is running with their own keyboard and mouse... but in my only experiences with such programs the lag time was so bad that it probably wouldn't be very effective. They probably have better programs for that sort of thing now, but... even so there's really only one interactive role to play in the game, and that's the commander of the boat, so at best you'd either have to take turns or issue orders by committee.
Personally I think the "one queen to a hive, one captain to a ship" rule is always the better way to go.
