The covered building slipways, together with the dry docks, formed the industrial heart of the Dockyard of the age of sail. Most ships were built on slipways that sloped into the river – located both here and in front of Commissioners House, although some were built in dry docks.
4, 5 and 6 slips were built as a group between 1847 and 1848. Their slender cast-iron frames were covered with corrugated-iron (now steel) sheeting. These roofs are an important landmark in the history of wide span iron and steel structures as they predate those of the great train sheds of King’s Cross and Newcastle and were part of the design path to the 1851 Crystal Palace
The last slip to be built was No.7, erected in 1855 with a frame built out of wrought-iron with integral overhead travelling crane rails. Most of the submarines built at Chatham between 1907 and 1966 were constructed there, including HM Submarine Ocelot. Today, No.7 slip is operated commercially by Turks Shipyard.
During the Napoleonic Wars the Navy Board set about minimising the impact of Dry Rot on ships under construction by building covers over the all the building slips and docks used for shipbuilding.
At Chatham the large slips in front of Commissioners House were tackled first, with No 2 Slip covered in 1813 and No 1 Slip in 1815. No 3 slip was built in 1836 and covered in 1838 with a roof 300 ft. (91m) long and 146 ft. (44.5m) wide. The cantilevered frame was to the design of Sir Robert Seppings and is a remarkable tribute to the skills of the dockyard workforce which built it. Today it remains the sole survivor, No.1 Slip was taken down at the end of the 19th century while No.2 Slip was lost to fire in 1966.
By the 1850s the length of ships had outgrown the slipway and in 1904 a new mezzanine floor was inserted to create a store for ships’ boats.