Sydney Ferries Limited generally choose Australian Aboriginal names for the early twentieth "K-class" steamers.

The Kirrule-type continued the K-class double-deck, double-ended screw propulsion, rounded bows with two raised wheelhouses and a single tall funnel.

In the 1930s, following the opening of the Sydney Harbour bridge, the white trim and varnished timber was painted over with a green and cream colour scheme.

Kirrule, Kiandra and Kubu were the second largest type of inner harbour vessels and were built to meet the increasing North Shore demand.

[4] Passenger numbers continued to fall after World War 2 to around 9 million annually, and the privately operated Sydney Ferries Ltd fleet was taken over by the NSW State Government in 1951.

While Kanangra was being converted from steam to diesel power in the late 1950s, Kubu was the heavy lift ferry of the inner-harbour fleet.