Naval Tactical Data System
In 1971, all three ships were marked for modernisation, primarily involving updates to the missile and gunnery systems, along with the installation of the Naval Combat Data System (an derivative of the United States Navy's Naval Tactical Data System modified for the "Perth"s). "Hobart" was refitted in San Francisco during 1972, but instead of following through on plans to update all three ships in American shipyards, the RAN decided to upgrade the other two destroyers at Garden Island instead to give the dockyard experience in refitting the destroyers.