Fremantle - class patrol boat The " Fremantle " - class patrol boats were coastal patrol vessels operated by the Royal Australian Navy ( RAN ) from 1979 to 2007 . Designed by British shipbuilder Brooke Marine and constructed in Australia by North Queensland Engineers and Agents , the " Fremantle " class were larger , more powerful , and more capable than the preceding " Attack " class , and the two primary patrol boat bases required infrastructure upgrades to support them . Although up to 30 vessels were planned , fifteen were ordered and constructed , with an unexercised option for five more . Their retirement was announced in 2001 and a decommissioning schedule published in 2004 . From May 2005 they were replaced by the " Armidale " - class patrol boat s with the last two " Fremantle " s decommissioning in May 2007 . The " Fremantle " class has also appeared in two drama television series based on the Royal Australian Navy . Planning and development . The concept for the " Fremantle " class began somewhere between 1967 and 1969 , as the " Attack " class patrol boats entered service , and areas for improvement were observed . In September 1970 , the RAN announced the intention to construct ten new patrol boats , which would operate in tandem with the " Attack " class and replace two general purpose vessels . These new vessels were intended to enter service between 1976 and 1980 . The number of vessels to be built fluctuated , peaking at thirty vessels ( 16 RAN , 4 Royal Australian Naval Reserve , and 10 for the military of Papua New Guinea ) , and settling at fifteen . Plans of acquisition were announced in April 1975 , with eleven shipbuilders submitting tenders , of which two were shortlisted in 1976 ; Brooke Marine of the United Kingdom and Lürssen Werft of Germany . Brooke Marine won the contract to design and produce the lead ship , with North Queensland Engineers and Agents contracted to build the other fourteen vessels . An option for an additional five vessels existed , but they were placed on indefinite hold in 1982 . There was a separate acquisition plan for six missile - armed variants , but this was suspended due to the lack of available funding , and the belief that such ships could be constructed on short notice if required . Design and construction . The design of the " Fremantle " class called for ships with improved seakeeping , and newer equipment and weapons than those fitted to the " Attack " class . The " Fremantle " s had a full load displacement of , were long overall , had a beam of , and a maximum draught of . The " Fremantles " were 28 % longer and 50 % heavier than their predecessors . During sea trials , NUSHIP " Fremantle " was revealed to be 20 tons over the contracted limit . Main propulsion machinery consisted of two MTU series 538 diesel engines , which supplied to the two propeller shafts . 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 . The ship ' s company consisted of 22 personnel . Each patrol boat was armed with a single , bow - mounted 40 mm L / 60 Bofors gun as main armament , supplemented by two . 50 cal Browning machineguns and an 81 - mm mortar , although the mortar was removed from all ships sometime in the late 1990s . 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 . Early on in the construction program , it was realised that the two main patrol boat bases , HMAS " Cairns " in Cairns , Queensland and HMAS " Coonawarra " in Darwin , Northern Territory , were not capable of supporting ships of this size on a permanent basis . This resulted in a $ 10 million infrastructure upgrade for the two bases , which was completed in 1981 and 1982 , respectively . This included modern maintenance , logistic , and administrative facilities at both bases , and the installation of a synchro - lift at " Coonawarra " . Construction of " Fremantle " began in October 1977 . She was launched on 16 February 1979 , and commissioned on 17 March 1980 . During sea trials , " Fremantle " received distinction for locating and rescuing a British sailor thrown from a commercial trawler following its collision with an oil tender . Construction of the first Australian - built vessel , , began in September 1978 , with " Warrnambool " launched on 25 October 1980 and commissioned on 14 March 1981 . The final ship of the class , , was commissioned on 15 December 1984 . The Australian - built vessels were built through an assembly - line method . Hulls were built upside - down from the keel to the second - uppermost deck , then rolled over and built to the top of the hull . After this , the superstructure , which had been fabricated at the same time , was welded onto the hull . Construction of the class ( including the two naval base upgrades ) cost $ 150 million . All fifteen vessels were named after " Bathurst " class corvettes . Operational history . The first ship of the class , , arrived in Australia on 27 August 1980 , after an 82 - day voyage covering . North Queensland Engineers and Agents completed three patrol boats in both 1981 and 1982 , and four in both 1983 and 1984 . By the end of 1984 , four " Fremantle " s were located at HMAS " Coonawarra " , HMAS " Cairns " , and Fleet Base East , two at HMAS " Stirling " , and one at HMAS " Cerberus " . Also by 1984 , all of the " Attack " class had left active service , with many transferring to the RAN Reserve or the Indonesian Navy . On 31 May 1985 , " Wollongong " grounded on rocks at Gabo Island , causing extensive damage to the vessel . She was repaired by the builder , and returned to service in late 1986 . From May 2005 onwards , the " Fremantle " s were replaced in service by the fourteen " Armidale " - class patrol boats , with the last two ships , and , decommissioned in a joint ceremony on 11 May 2007 . As of 2008 , " Townsville " and have been marked for preservation as museum ships in their namesake towns . The other thirteen ships of the class have either been sold for scrap , or are awaiting disposal . During late 2008 , remained laid up alongside " Waterhen " in Waverton , Sydney for use as the alongside set for the drama series " Sea Patrol " . " Fremantle " class in fiction . The fictional HMAS " Defiance " , portrayed by HMA Ships , , , , and featured in the second season of the ABC TV series " Patrol Boat " . The fictional HMAS " Hammersley " is the setting of the first season of Channel Nine ' s 2007 drama series " Sea Patrol " . This vessel was portrayed by HMA Ships " Wollongong " and . A second patrol boat , HMAS " Kingston " , also appears in the series . From the second season onwards , an " Armidale " class boat is used .