The USS Constitution began entering into dry dock at the Charlestown Navy Yard late Monday night for a three-year restoration project, officials said.
The restoration will include replacing 3,400 sheets of copper to protect the ship’s hull below the waterline and replacing some deck beams, Navy Commander Paul J. Brawley said. The work is estimated to cost $12 million to $15 million, which is being paid for by the US Navy.
“There’s been no damage to the ship,” Brawley said. “This is done every 15 to 20 years.”
According to Brawley, the ship began entering the dry dock at 10:12 p.m., and the process was expected to be completed some time after midnight.
The ship was last dry-docked in 1992.
This year’s dry-docking was originally scheduled for March 20, but was delayed because of the region’s severe winter. Dry dock 1’s new caisson door, which is used to help raise or lower the ship for repairs, faced many delays on its way from New York, Brawley said.
The purpose of the restoration is not to make the ship new, but rather to preserve its history for many years to come, Brawley said.
“When you think about the ship’s design, the construction materials, and the mission to keep sea lanes open, all these themes carry on today,” he said. “There’s a very strong tradition, and the USS Constitution embodies everything the US Navy is.”Globe correspondent Adam Sennott contributed to this report. Aneri Pattani can be reached at firstname.lastname@example.org. Follow her on Twitter @apattani95.