No, I was thinking more like beeing together on the same U-Boat, like on many other games, where you coop together in the same plane, or tank etc.
For instance, before leaving a port, just log into a specific patrol and join by logging in with a specific i.p. address.
I guess it would be a veeeery long trip to join, if it wouldn't be possible to use the time compression.
To be able to multicrew on the same U-BOat for a specific amount of members, I think would be very exiting. As long as one can anyway walk around the sub, it would be great to have one in the Torpedo room, Radio room, map etc.
But this wish will probably never come true anyway....