DryDocks

Drydocks are specialized facilities used for the construction, maintenance, and repair of ships and other watercraft. They allow hulls to be worked on below the waterline by removing water from a watertight chamber or by using a floating structure that can be submerged and raised. Typical operations involve docking the vessel between gates or within a chamber, closing the gates, pumping out the water, and then performing hull inspection, cleaning, painting, welding, or replacement of appendages. The vessel is then re-ballasted, the chamber is flooded, and the ship is freed.

There are two main types: graving docks (also called dry docks) and floating drydocks. A graving dock is a fixed, watertight basin with gates at the entrance; water is pumped out to expose the hull. A floating drydock consists of large, buoyant pontoons that are submerged and then towed to a vessel, raised to lift the ship, and later sunk to lower the ship for release.

History and use: Drydocks have been used since ancient times in larger ports and evolved substantially with the growth of steam-powered and larger ships in the 19th and 20th centuries. They remain essential in naval shipyards and commercial shipyards for hull inspections, anti-corrosion work, propeller and rudder repairs, and major overhauls.

Limitations and considerations: Drydocks require substantial port infrastructure, including gate structures, pumping stations, and space for large vessels. Availability can constrain repair schedules, and the process can be weather dependent for floating options. Environmental controls and safety procedures are important during docking and undocking operations.

See also: Shipyard, Floating crane, Graving dock.