The undocking of "Old Ironsides" on Sunday marked the end of restoration work that started two years ago, officials said. The most recent work included replacing 100 hull planks and installing 2,200 new copper sheets, 500 of which were signed by nearly 100,000 museum visitors, said USS Constitution Museum President Anne Grimes Rand, who called the ship "a wonderful symbol for our democracy." The Constitution entered the dock at the historic Charlestown Navy Yard on the night of May 18, 2015, and on Sunday — a day that was expected to have the highest tide of the summer — the dry dock at the navy yard was flooded, and the ship was lifted off the keel block.