See main article: Fremantle-class patrol boat. Starting in the late 1960s, planning began for a new class of patrol boat to replace the, with designs calling for improved seakeeping capability, and updated weapons and equipment.[1] The Fremantles had a full load displacement of, were long overall, had a beam of, and a maximum draught of .[2] Main propulsion machinery consisted of two MTU series 538 diesel engines, which supplied to the two propeller shafts.[2] Exhaust was not expelled through a funnel, like most ships, but through vents below the waterline. The patrol boat could reach a maximum speed of, and had a maximum range of at .[2] The ship's company consisted of 22 personnel.[2] Each patrol boat was armed with a single Bofors 40mm gun as main armament, supplemented by two .50 cal Browning machineguns and an 81 mm mortar,[2] although the mortar was removed from all ships sometime after 1988. The main weapon was originally to be two 30 mm guns on a twin-mount, but the reconditioned Bofors were selected to keep costs down; provision was made to install an updated weapon later in the class' service life, but this did not eventuate.[3] [4]
Whyalla was built by NQEA in Cairns, Queensland.[2] The ship was laid down on 13 July 1980, launched on 22 May 1982, and commissioned on 3 July 1982.[5]
Whyalla was based at, and was decommissioned on 2 September 2005.[6] The patrol boat was broken up for scrap in Darwin during 2006, at a cost of $450,000 to the Australian government.