The world's oldest commissioned warship still kept afloat will be spending a little time in dry dock undergoing repairs to keep it watertight.

Launched in 1797, the USS Constitution was among the first six frigates built for America's Navy after the Revolutionary War. To ensure the ship remains intact, the aging vessel was recently removed from the water to undergo major repairs at the Charlestown Navy Yard in Boston where visitors can still walk the deck.

"We are making history," said historian Margherita Desy of the Naval History and Heritage Command Detachment Boston, who serves as a principal expert on the USS Constitution. "I was here in the last restoration in the 1990s and to be part of another restoration with USS Constitution, to be working with the oldest commissioned warship afloat in the world, the only vessel left that helped to begin the United States Navy in the 1790s, is a thrill."

While in dry dock the hull of the legendary vessel is fully visible. A view of the ship's underside reveals a rare glimpse of the oxidized copper sheathing that has protected it from wood boring mollusks and saltwater for decades. The 3,400 sheets will be removed and replaced. The process will briefly offer visitors a glimpse of the wood below.

The USS Constitution earned the nickname, "Old Ironsides," when cannon balls bounced off her frame during victorious battles against the British in the War of 1812. Thousands of sailors have served on the ship and today the USS Constitution remains staffed with a Navy crew.

Ship restorer Anita Petricone is among dozens of people tasked with repairing the vessel.

"This ship is alive," said Petricone. "She's got all the energy accumulated from all her sailors, the battles, everything. She never lost a battle."

"I'm looking at how this has been put together over the years," said ship restorer John Hinckley, who sees the challenges and benefits of old construction meeting new. "Nothing is symmetrical. Everything is a little bit different."

Hinckley noted that repairs were done by hand in the past, but now, "We've got two cranes running to move this stuff around."

The restoration is expected to take more than two years and cost between $12  million and $15 million. The U.S. Navy will pick up the tab.

"The hope is that 217 years from now the ship will still be here, which would be pretty extraordinary," said Desy. 

Click for more details on the USS Constitution

Molly Line is a correspondent for Fox News Channel. Follow her on Twitter @MollyLineFNC.

Molly Line joined Fox News Channel as a Boston-based correspondent in January 2006.