The War of 1812-era frigate Constitution, the Navy’s oldest commissioned vessel, entered dry dock May 19 for a thorough overhaul. During the next several years, the ship – dubbed Old Ironsides – will receive new lower hull planking and caulking, copper sheets to protect its hull below the water line, some new deck beams, and preservation and repair of rigging, masts, and yards. The 217-year-old ship last was in dry dock in 1992.