Argo:
2 pilots,
2 navigation specialists,
2 comm specialists,
4 gunners,
10 repair crew,
2 janitors
If one days shift is 12 hours, than you need 1 pilot, 1 nav specialist, 1 comm specialist, 2 gunners, 5 repair crew, and 1 janitor, then the next shift would be identical, so you double the crew for one shift, and you get a total of 22. Even if the shift tme is different, you have to remember that a ship doesn't just go to sleep when the crew is tired, but no matter what the local time is, or how long the local day is, there is still a ships-night, so they need a day crew and a night crew.
[edit] I for got to put a ... at the end...[/edit]...