The Great Dry Docks at Erie Basin page
“The Largest Dry Docks in the country, and probably the largest in the world, are located at the Erie Basin, South Brooklyn, N.Y.”
Scientific American. January 13, 1883
A dry dock is a tapered channel with a floating or hinged watertight gate at one end. A ship is floated into the water filled dock, the gate is shut, props are placed to hold the ship up and then the water pumped out leaving the vessel dry and its hull able to be worked on. When the work is done, the ship is refloated by filling the dock to the height of the water on the other side of the gate, the gate opened and the ship floated back out.
In 1883, the largest docks, able to fit large ships were in Erie Basin. James E. Simpson completed the first of Erie's dry docks in 1866 two years after the basin was completed and promptly started on a second one.
Dock No. 1 had an interior length of 510 feet and was 124 feet wide at top. The depth of the gate below highwater was 22 feet.
Dock No. 2 had an interior length of 600 feet and was 85 feet wide at top. The depth of its gate below highwater was 25 feet.
Scientific American published an illustrated overview of how the dry docks at Erie basin worked on January 13, 1883.