This is a model of a Floating Dry Dock which is designed to lift ships completely out of the water to allow repair work or maintenance to be carried out on the hull below the waterline.
Floating Dry Docks are submerged in the water by filling tanks with ballast water until there is sufficient draught to allow a ship to enter. Once the ship has entered the dock and is moored in the correct position over the blocks the ballast tanks are pumped out and the dock rises to its normal position lifting the ship clear of the water.
This model is based on the Admiralty Floating Dock (AFD) design of the Royal Navy which was deployed throughout the British Empire to provide maintenance facilities in support of the Fleet. AFDs were used extensively in the Pacific Theatre during the Second World War to provide repairs for ships damaged in battle.
Swan, Hunter & Wigham Richarsdon Ltd were the leading builder of AFDs for the Royal Navy including AFD 10 with a 50,000 ton lifting capacity which was built for the major Royal Navy base at Singapore. One of the largest ship wrecks in the world is the 80,000 ton AFD 23 which sank on 8th August 1944 when a buoyancy tank broke loose while the 30,000 ton battleship HMS Valiant was in dock off the coast of Ceylon ( Sri Lanka ).
This model with a scale length of 850 feet and internal clearance of 112 feet 6 inches between the wing walls represents one of the larger AFDs with a lifting capacity of around 30,000 tons.