PEARL HARBOR (NNS) -- Nearly 100 Pearl Harbor Naval Shipyard (PHNS) employees undocked USS Missouri (BB-63) Jan. 7 in support of the floating naval museum's return to "Battleship Row" next to the USS Arizona Memorial.
"Pearl Harbor Naval Shipyard played a key role in winning World War II, so shipyard workers have tremendous appreciation for Missouri's historical significance," said PHNS Commander Capt. Gregory Thomas.
As the 54,889-ton ship glided over the sill of Dry Dock 4, Missouri entered the harbor waters for the first time in more than two months. The ship had been dry-docked at PHNS since Oct. 14 for $18 million of maintenance and preservation work.
"We are proud of our role in helping to preserve this vital symbol of victory over oppression in World War II - but we are also humbled," Thomas said. "We are in awe of the great men and women who served on Missouri over five decades and in three wars."
Thomas also said the historic significance of the vessel was recognized by several PHNS employees.
"It was particularly moving for shipyard workers to look upon Missouri, sitting proudly in our dry dock as we went to work the morning of Dec. 7, 2009," he said.
The majority of the maintenance and preservation work was performed by BAE Systems Ship Repair, the lead public-private venture partner with the shipyard. The shipyard supported the effort by docking and undocking the vessel.
Engineers planned the dry-docking and riggers, shipwrights and other shipyard workers placed 309 four-ton keel blocks to support the battleship, more than five times as many keel blocks required to support a modern guided-missile cruiser.
Missouri's docking was completed on schedule, within one minute of the planned 10-hour evolution, and within one foot of each of the 309 keel blocks.
The same engineers and naval architects planned for the successful undocking, and a small team from PHNS's Environmental Division provided environmental oversight.
Despite the vessel's successful docking, however, the massive, 887-foot-long battleship presented unique challenges during the undocking evolution.
"The shipyard docking team completed extensive preparations to control this large vessel," said Dockmaster Sonny Del Toro. "During planning, we kept asking how we could make the process better for battleship Missouri."
Docking Officer Lt. Lorenz Tate pointed out two unusual concerns undocking the battleship presented: ensuring the watertight integrity of Missouri's hull and the number of people aboard the ship.
"It's different from an operating (U.S. Navy) ship, where you know the integrity of the hull," he said. "With (Missouri), you don't know, given the age of the ship and the age of the hull. You have to plan for scenarios, such as leaking."
Nearly 1,000 passengers were aboard Missouri for the two-mile journey to Ford Island, and their movement had to be controlled during the initial phase of undocking because it could mask indications of shipboard flooding, he said.
Approximately 500,000 gallons of ballast water were placed in selected tanks, voids and spaces aboard Missouri to properly balance the vessel for lifting off the docking blocks without damaging the blocks or the ship.
When 53 million gallons of seawater flooded the dry dock, shipyard employees began thorough inspections aboard Missouri, checking the ship's water-tight integrity.
Missouri was also closely monitored to determine if the ship was listing too far to port or starboard, an effort to observe potentially adverse flooding into the empty tanks around the plating, according to PHNS Naval Architect Jason Morrison.
"In regular spaces, it is one thing (to check for leaks), but it is tough with the tanks, and Missouri has roughly 600," said Morrison. "That's why it was very important for the ship riders to stay very still as the ship lifted off."
After Dry Dock 4 was filled to sea level, the caisson - the "door" to the dry dock - was removed, and the docking team carefully guided the ship to the dry dock's entrance. There, four tugboats met the battleship, pushing and pulling the historic vessel to Foxtrot 5 Pier at Ford Island.
The USS Missouri Memorial Association will resume tours of the ship the weekend of Jan. 29.
The U.S. Navy donated the ship to the Missouri Association in 1998 as part of the Ship Donation Program authorized by Congress. The battleship is one of 46 museum ships donated by the U.S. Navy.
"(Missouri) is a national monument. We have to save it. If we lose this ship, we'll lose an important piece of history," said PHNS Environmental Protection Specialist Gail Shon.
PHNS is the largest industrial employer in the state of Hawaii with a combined civilian and military workforce of more than 4,700 personnel.
For more information on PHNS, visit www.navsea.navy.mil/shipyards/pearl.
Fore more news from Pearl Harbor Naval Shipyard, visit www.navy.mil/local/phnsy/.