Preparations are underway for the USS Constitution's move to dry dock for major restoration.

The world's oldest commissioned warship still afloat will begin undergoing two years of repairs at the Charlestown Navy Yard historical park in Boston beginning Tuesday.

On Sunday, the dry dock is being flooded to allow the historic ship to enter on Monday.

The project could cost the Navy as much as $15 million. It will include re-coppering the hull, replacing worn rigging and old planks and making general repairs to the stern, bow and captain's cabin.

The ship will be open to visitors during most of the work, beginning in June.

The last time the Constitution was dry-docked was in 1995, in preparation for its bicentennial.

The ship was launched in 1797 and is a major tourist draw.