What is an excavation that can be flooded when a caisson is opened, allowing a ship to float inside and then be sealed?

A graving dock is indeed an excavation designed for allowing ships to float inside, where it can be sealed for maintenance or repair. This structure is typically constructed on land and is often used for the docking and servicing of vessels. When the caisson is opened, water can fill the dock to allow the ship to float in. After the ship is inside, the caisson is closed, and the water can be drained, allowing the ship to rest on blocks for maintenance work.

Understanding the role of a graving dock highlights its importance in shipyard operations. It is distinguished from other types of docks by its ability to be drained of water after a vessel is secured inside, facilitating work on the hull and other underwater components. This makes it an essential structure for shipbuilding and repair processes, where accessibility and safety are paramount.