The dry docks were used for both shipbuilding and ship repair. During the age of sail the Navy Board built more dry docks than any other country. Originally they were built of timber and needed frequent repair and re-building.
No. 3 dry dock, now home to HM Submarine Ocelot, was the first of Chatham’s dry docks to be built in stone. It was designed by naval architect John Rennie, along with the South Dock Pumping Station.
No.4 dry dock, where HMS Gannet is now berthed, was constructed in 1840 and enlarged in 1908 to accommodate larger ships.
Both dry docks were built in the same in the same manner with floor and sides of granite blocks supported underground by an inverted brick arch.
This was the site of the Old Single Dock where HMS Victory was built and launched in 1765.
As ship building changed from wood to iron and the size of vessels increased, there was a need to extend the dock. Between 1855 and 1856 it was lengthened and rebuilt in stone. In 1860 this dock was used to construct HMS Achilles, the first iron battleship to be built at a Royal Dockyard, a sister ship to Warrior, who still survives today at Portsmouth Historic Dockyard.
Designed by John Rennie as part of the works to build No 3 Dry Dock, this was Britain’s second large volume steam powered pumping station.
Connected to all three docks and the river by a series of underground culverts it was used to drain the docks when ships were brought in for repair or after a launch. The water was pumped back into the river through the underground drainage system.
The Pumping-Station was powered by two steam powered beam-engine and this was replaced by in 1929 by an electric pump. The pumping-station remains operational and could be used when the docks are drained to carry out major works on the ships, although this does not happen often.