Ted Diro replaced . Australia transferred the vessel to Papua New Guinea on 30 November 2018.
Following the United Nations Convention on the Law of the Sea extension of maritime nations' exclusive economic zones to 200km (100miles) Australia agreed to provide twelve of its neighbours with twenty-two Pacific Forum-class patrol vessels, so they could exercise sovereignty over their own territory, using their own resources. The first vessel was delivered in 1987, and in 2015 Australia announced plans to replace the original patrol boats with larger and more capable vessels.
Australian ship builder Austal won the $335 million Australian dollar contract for the project, and built the vessels at its Henderson shipyard, near Perth. Guardian class vessels were designed to use commercial off-the-shelf components, not cutting edge, military grade equipment, to make them easier to maintain in small isolated shipyards.
The vessels are 39.5m (129.6feet) long, can travel 3000nmi at 12knots. Their maximum speed is 20knots. Their design allows the recipient nations to mount a pair of heavy machine guns, on either flank, and possibly an autocannon of up to 30mm, on the foredeck.
Ted Diro was the first Guardian-class vessel to have her keel laid in July 2017. She was the first to be launched, in May 2018. She began her formal sea trials on 9 August 2018. The patrol vessel is scheduled to be commissioned in late October, when her acceptance trials are completed.
On 22 October 2018 the Post Courier reported that delivery was scheduled for December. Diro, head of the PNGDF Major General Gilbert Toropo and Angus Campbell, Chief of the Australian Defence Force, attended the vessel's commissioning, on 1 February 2019.
In August 2019 two warships of the Japan Maritime Self-Defense Force visited Port Moresby. The Japanese vessels hosted the crew of Ted Diro, together with local VIPs, and her crew hosted visiting Japanese personnel on tours of Ted Diro.
On 17 October 2019 The Australian reported that Ted Diros engines had broken down, and she had to be towed back to Cairns, for repairs.