The New South Wales Public Works Department declared Cockatoo Island the state dockyard.

[1] Following Federation, in 1913 Cockatoo became the Commonwealth Dockyard, and the island, both through shipbuilding and servicing, played an important role both in the development of the Royal Australian Navy and during World War I.

From 1933 the dockyard was leased from the Australian Government by Cockatoo Docks and Engineering Co Ltd and the island played a very significant role during World War II.

It was then said to be the biggest dry dock in the world (in terms of its width and depth of water over the sill) and was one of Australia's most significant engineering projects to that time.

The dock was named after John Sutherland, the Minister for Works in the government of Sir Henry Parkes, and cost £267,825.

A special feature of the design was the caisson (or "gate" of the dry dock) which was very heavy wrought iron, pulled by an endless chain horizontally on bronze rollers and it moved in a particularly effective fashion; it was steam powered but was converted to electricity in 1918.

Much of this role transferred to Garden Island following the completion in 1945 of the bigger Captain Cook Graving Dock, but Sutherland still took large ships, and HMAS Melbourne docked at Sutherland after the tragic collisions with HMAS Voyager and USS Frank E. Evans.

[1] Criterion B: Rarity The enlargement of the dock over time reflects the development in warship construction, and shipbuilding more generally, during the early twentieth century.

[1] Criterion D: Characteristic values Sutherland Dock is important as an example of a nineteenth century harbour facility of this type.

It was one of Australia's greatest engineering projects (and remained the nation's largest dry dock until 1945), and therefore has considerable technological significance.

[1] This Wikipedia article was originally based on Sutherland Dock, entry number 105260 in the Australian Heritage Database published by the Commonwealth of Australia 2018 under CC-BY 4.0 licence, accessed on 15 September 2018.