Updated

Another exclusive "men's club" is about to go coed: The U.S. Navy will soon allow women to serve on submarines.

Women have served side-by-side with men for decades in all branches of the military, but submarines, up until now, have remained off-limits. The reason, the Navy says, was privacy. Crew members generally sleep 9 to a room. Up to 40 people can share one bathroom. Even officers bunk together.

There was also the unspoken concern: men and women living 24/7 in extremely close quarters might develop uncomfortably close relationships.

Small "attack" submarines simply were not designed to allow one population to have separate quarters and bathroom facilities. And while larger, defensive subs could have accommodated women, the Navy said that allowing women to serve only on those vessels would have put them at a disadvantage when seeking promotion within the ranks, since they would have to compete with men who had served in both attack and defensive vessels.

But now, with the introduction of its new Trident guided missile submarines -- subs as large as the defensive ballistic missile submarines but outfitted to carry out offensive missions -- the Navy says it finally will be able to offer women both privacy and a viable career path.

Because a junior officer's room was designed to bunk three people, the Navy plans to admit three women -- two junior officers and a senior officer -- onto each of its eight Trident submarine crews by January 2012.

They will have to share a bathroom with nine men, but the Navy says the crew will use a simple reversible sign to indicate who is using the facilities, enabling both sexes to get the privacy they demand. No modifications required.

But not everyone's on board.

John Mason, a retired senior chief petty officer who served on four ballistic missile submarines and served on two surface ships with women, is one of many retired officers who say bringing women on submarines will be easier said than done.

"It is impossible to pass one another in most passageways or working areas without turning sideways to pass one another," Mason wrote in a letter posted on the Navy Submarine Group Ten's official blog. "It is almost inevitably that some form of physical contact will occur.”

"During times of emergencies," he continued, "the situation becomes even more critical because shipmates are rushing to their casualty or their battle station, some going forward, some going aft, some climbing over one another to relieve a watch station. All of these actions are critical to ensure the safety of the mission, the ship, and the crew. And all of them result in physical contact of one form or another."

Combine that physical closeness with being out to sea for up to four months with minimal outside contact, and you're just asking for trouble, Mason says.

"Sexual harassment forms a major factor in the workplace environment, whether military or civilian, for very good reasons," he says. "You cannot close the hatch on a submarine, submerge, and tell the crewmembers, 'don't act human.' We can have idealistic expectations, but we must live in a realistic world."

The Navy says it is being realistic -- by realizing that it's not meeting its officer recruiting goals and that more and more women and fewer and fewer men are getting technical degrees.

"We need to open up that aperture so we can bring in these highly qualified, intelligent, enthusiastic women into the submarine program so we can maintain our personnel rankings," Rear Adm. Barry Bruner told FoxNews.com.

Also, Bruner says, sailors aboard submarines today don't have the same "hangups" as prior generations.

"They don't really care if it's a man or a woman. They don't really care if he or she is black or white, tall or short, fat or thin. What they care about is can they do their job," he said.

But some of the sailors' spouses don't share that indifference.

"The Navy wives, I think, are the most vocal," said Linda Cagle, the owner of a restaurant near the Kings Bay Naval Submarine Base. "They do not think it's a good idea, they do not want women on submarines with their husbands or their boyfriends."

The Navy hopes the penalties for "fraternizing" -- ranging from fines to dismissal and two years' confinement – will ease some of those concerns.

And if crew members were to defy the rules? If a sailor got pregnant on board, the Navy says, it would get that woman off the submarine as soon as possible, just as it does if a male sailor has a medical emergency.

"Every week or two weeks or month, at least, we have a significant health issue on a submarine," Bruner said. "It might be an acute appendicitis; it might be a heart condition. It could be anything ranging from significant problems with your eyes to who knows what -- a broken bone -- and we would handle the pregnancy the same way that we do those injuries."

But considering that less than 1 percent of women in the Navy have become pregnant while on board surface ships, he said he doesn't anticipate having to deal with that issue often, if at all.
One issue he is dealing with is whether the policy will carry over to the enlisted ranks, where more than 80 sailors, some as young as 17, sleep nine to a room and share two bathrooms.

"To bring women enlisted on board we'd actually have to make modifications to the ship," he said. "I can't tell you exactly what they would be, because although we're beginning to look at this, we really haven't gone far enough down the road to determine which submarines we're going to put them on and how we're going to make sure they have privacy."

The Navy says it isn't having a problem meeting its recruitment goals for enlisted sailors, so it has time to explore the issue. And it sees no better starting point than admitting female officers.

"Anytime our culture has made progress there are challenges associated with it," Bruner said. "So there are challenges with this. But if there's anything that I've learned in my time in the service, it’s that we make no changes without a lot of forethought and a lot of detailed planning."