What’s the difference between a dry dock and a graving dock?
A dry dock usually refers to a a floating, but submersible, barge with tall high hollow sides and open ends, that can be partially sunk to allow a vessel to float over the deck of the barge, subsequently to be raised by pumping out the dry dock until the surface of the barge clears the water, and the vessel is high and dry. A graving dock is a type of dry dock that is a large pit in the ground, separated from a waterway by a floating or hinged gate. Once a ship enters a graving dock, the gate is shut, and all water pumped out, leaving the vessel dry so that its bottom can be worked on. To re-float the vessel, the pit is simply flooded until the water level matches that on the other side of the gate, and the gate is opened or removed.
