KINGS BAY NAVAL SUBMARINE BASE, Ga. — Aboard the submarine USS Florida, there's no e-mail or phone, no breaks for sunshine or fresh air. For many Navy sailors serving 90-day tours in cramped quarters underwater, one of the few creature comforts has been smoke breaks below decks around a butt bucket in the machine room.

By New Year's Eve, sailors will have to kick the habit.

In early April, the Navy ordered its fleet of 71 submarines to snuff out smoking onboard by the end of 2010 — closing one of the last loopholes in an indoor smoking ban the U.S. military imposed in 1994.

The change means an estimated 5,200 smokers in the submarine fleet will have to pretty much quit a habit that for some is a pack a day, for others an occasional cigar.

"You're going to have some very, very disgruntled sailors," said Petty Officer 3rd Class Cedric Dickinson, a cook aboard the Florida who's already cutting back from a pack a day to four cigarettes. "You don't have much to look forward to under way. Everyone's going to be on edge."

The pending smoking ban was announced 16 years after the military extinguished tobacco smoke in most other indoor areas, from base office buildings to Air Force hangars, Army tanks and below decks on Navy surface ships.

The Navy made an exception for submarines. Sailors spend up to three months on undersea patrols without shore leave or even surfacing for sunlight.

Privacy is minimal and space so limited that sailors wait in line for showers, a seat in the mess hall for meals and cigarette breaks. On the Florida, only three sailors at a time can light up, while other smokers wait their turn.

"Once you lock these sailors into a submarine, the stress level is incredible," said Master Chief Petty Officer Randy Huckaba, the top enlisted sailor in one of the Florida's two crews, who estimates that a third of the 160-man crew smokes. "There are times when the only release is to smoke a cigarette or go listen to music."

For years the Navy assumed that, aside from smoke wafting around a sub's designated smoke pit, secondhand smoke was scrubbed from the air by the same filters that remove fumes from cooking and cleaning chemicals.

But a 2009 Navy study showed otherwise. The Navy tested 197 nonsmoking submarine sailors for nicotine in their systems, while they were on shore duty and again after they returned from deployment at sea. Most had none while assigned to shore, but all tested positive for nicotine exposure after returning from patrols. The Navy concluded that all submarine sailors are inhaling secondhand smoke, whether they can smell it or not.

"The only way to eliminate it is to eliminate smoking within the submarine," said Lt. Cmdr. Mark C. Jones, a spokesman for Navy Submarine Forces in Norfolk, Va. "This is for the majority of sailors who have chosen not to smoke tobacco. It's for their health."

In a Navy survey, 40 percent of its 13,000 submarine sailors said they smoke at sea. That's 5,200 smokers — though Jones noted that that group ranges from pack-a-day smokers to those who have an occasional cigar.

Vice Adm. John J. Donnelly, commander of the submarine fleet, announced the smoking ban April 8.

At Kings Bay Naval Submarine Base, the East Coast hub for the Navy's nuclear-missile-armed subs, base commanders are preparing.

Former smokers aboard each submarine are being trained to lead fellow sailors through smoking cessation classes. Medical officers are preparing to order nicotine gum and patches in bulk to stock each ship. (Sailors aren't allowed to use drugs like Zyban and Chantix, which can have psychological side effects.)

One thing smokers requested almost unanimously is for cutbacks in smoking at sea before having to go cold turkey next year, said Master Chief Corpsman Michael Leggett, who oversees the submarine medical officers at Kings Bay.

So some commanders plan to give the no-smoking policy a trial run before Dec. 31. Huckaba said smoking on the Florida's upcoming tour will be discouraged, and times when lighting up is permitted may be curtailed. For the crew's last week at sea, the commander plans to ban all smoking.

The worst thing smoking sailors could do is put off quitting until the last minute, said Bill Blatt, who oversees quit-smoking programs for the American Lung Association. Normally, it takes smokers three to four weeks before their tobacco cravings subside, Blatt said. Even after that, quitters are at high risk of relapsing for another six months to a year.

Also key to success — having a personal desire to quit, which may be absent in many sailors being forced to by the Navy.

Sailors who have already quit and are being groomed to mentor their colleagues say the toughest part is finding other ways to fill time off with the limited options available underwater.

Petty Officer 2nd Class Jarrod Gibbons stayed in the workout room rather than the smoke pit on his last tour aboard the USS Georgia. Petty Officer 2nd Class Nicky Bates packed plenty of books in place of his cigarette stash.

"When you go out to sea and submerge, sometimes it's the most boring, stagnant time you've ever seen," said Chief Petty Officer Jeff Bortzfield, who'll be a quit-smoking mentor on the USS Alaska. "And that's going to be hard."