My understanding from watching the Military Channel and the History Channel is that submarines are built with the same size doorways, bunks, etc as any other ship. Sure there is not the same amount of room to be spacious in general, but the basic dimensions of the shipboard facilities are the same. They may like shorter statured crewmen for submarines, but I don't think it's a requirement based on the type of vessel. But I didn't think they had females on subs yet, since they deploy under isolated conditions for months at a time. Submarines are considered a combat vessel, and I don't know if they still have the prohibition on women in front line combat vessels. Then again, I've heard of women serving on aircraft carriers and even saw some in one of the shows I watched, so maybe they've changed their rules.