Larger than the Titanic, the USS Missouri BB-63 — The Mighty Mo — was 58,000 tons of steel and armament, backed by nine fire-breathing 16-inch/50 caliber guns. Yet the ship could tear through the sea at an astounding 33 knots without breaking a sweat.

And although the world's most historic battleship hasn't moved at all since it officially opened its gangplank to the public on Jan. 29, 1999 — 55 years to the day after its launching — the ship's been anything but idle.

In July 2004, it welcomed its two-millionth visitor, and more than 400,000 folks have traipsed over the decks since then.

In six years, some 45,000 volunteer helpers have scrubbed, sanded and spiffed up every inch of the ship. Thanks to ongoing restoration projects, Engine Room No. 4 and Gun Turret No. 3 have been added to the ship's public tours. And it has started an overnight youth encampment program.

This year, the ship opened its "Truman Line" food service and chow line, named in honor of President Harry Truman's preference for eating with enlisted sailors during his 1947 Missouri cruise. In the next few months, the Missouri will open its ambitious Chief Petty Officer Legacy Center.

"I didn't think we'd get here this fast," said Don Hess, president and chief operating officer of the USS Missouri Memorial Association, which operates the floating museum berthed at Ford Island.

Even as Hess spoke, tour guide Marc Weintraub, deep in the lower decks, was leading an Explorer group of about two dozen through the aft gun plot room from which the Mighty Mo's 16-inch guns were fired.

"If any of you've ever been rabbit hunting, you know how difficult it is," said Weintraub. "That's the same thing that happens here."

Mighty Mo gunners had to calculate numerous factors — the range of the target, its altitude, how fast it's traveling in relation to the movement of the ship, wind velocity, temperature and so forth, Weintraub told the group.

Minor mysteries

This is the trigger for the main battery of 16-inch guns on The Mighty Mo, which was launched on Jan. 29, 1944. Gregory Yamamoto | The Honolulu Advertiser

Occasionally, retired Navy Master Chief's Boatswain Mate Les Lancaster will bump into a tour of visitors and pause for a chat.

"One of the perks of the job is that I can stop what I'm doing to give a visitor 10 minutes of conversation," said Lancaster, 49, director of the Missouri's shipboard operations and a man who's familiar with every inch of the battleship.

Another perk of having access to every part of a battleship so massive that its minor mysteries still abound.

"You find these little things all the time," Lancaster said. "You open up a cubby hole and go, 'Oh, looky there! — an old receiver they used on refueling stations,' or, 'There's part of the boat boom.'

"I keep hoping that one day I'll open something up and find it dated 1943."

Up on the main deck, Hess marveled at how far the Mighty Mo had come in only six years. If he had known in 1998 what the Missouri would be in 2005, he'd have been impressed with the outcome, he said.

"I thought we could do a lot. I think we've done more."

As for the Missouri's future, Hess is optimistic though less certain.

Christin Berner, a 16 year-old at Lanakila Baptist School, paints a firehose along with other volunteers on the battleship. The USS Missouri relies on more than 500 monthly volunteers to keep the ship in shape.

Staff guide Noel Peterson leads a group of tourists to the spot where the Japanese surrender was signed.

Unlike the Arizona Memorial, which receives government funding and is free to the public, the Missouri gets no government money and must pay its own way through ticket and concession sales, special events and donations.

The costs of operating and maintaining the Missouri, paying its staff of 115, and renting the F-5 Pier are considerable (the ship's electric bill alone comes to more than $255,000 a year).

Eventually, the Missouri will have to be completely repainted, which Hess said will cost around $1 million.

But what bothered Hess most were unknown factors — such as whether the Missouri will have to move from its location at Pier F-5, a ship's length away from the Arizona Memorial.

"There's some question marks," he said. "We're still temporary at this pier.

"I would hope that in the next 10 years we'll all understand that this is the right place, and that the Missouri should stay here."

To move the Missouri to a different location at Pearl Harbor would require around $6 million just to build a new pier. And Hess didn't even want to imagine the possibility of the Pearl Harbor shipyard ever closing down, as was briefly considered recently and something that could still become a reality.

"In the next five to 10 years, we're going to need to take the Missouri into dry dock," Hess said. "If they took the dry docks away ... we'd have to tow her all the way back to Bremerton, Wash.

"And think of the cost of that!"