was armed with five machine guns for self defence. The ship's company included 8 officers and 46 sailors. Originally, the RAN planned to have a ship specially constructed for the role. The decision to instead purchase an under-construction civilian tanker and modify her for military service allowed Sirius to enter service three years before originally planned, at half the acquisition project's planned cost. Operational history On the morning of 13 March 2009, Sirius was one of seventeen warships involved in a ceremonial fleet entry and fleet review in Sydney Harbour, the largest collection of RAN ships since the Australian Bicentenary in 1988. Sirius did not participate in the fleet entry, but was anchored in the harbour for the review. In 2010, Sirius was approved to carry and deploy boarding parties. This capability was tested during Exercise Kakadu 10, along with the ship's first ever dual replenishment. Sirius was forced to turn back en route to the RIMPAC 2010 exercise in Hawaii due to problems with her engine, and did not participate in the exercise as a result. The tanker completed a six-month maintenance period in Sydney on 16 September 2014; she spent five months of this period out of the water in the Captain Cook Graving Dock. HMAS Sirius joined , , and on their way to Pearl Harbor, Hawaii in preparation for RIMPAC 2020 on 6 August 2020. RIMPAC 2020 began on 17 August. End of service Sirius was originally expected to remain in service for approximately 15 years. In 2012, the ship was predicted to remain in service until the early 2020s. The 2013 Defence White Paper stated that the replacement of Sirius and would be brought forward. As well as building replacement vessels (either in Australia, overseas, or a combination), leasing existing vessels was also to be considered. In June 2014, the Minister for Defence announced that two companies had been invited to a restricted tender competition. Spanish shipbuilder Navantia is offering the design, while South Korea's DSME is proposing the downsized Aegir variant of the . The 20,000+ tonne ships will be built overseas, as they will be too large to build in Australian shipyards. Australia considered the design for their replacement tankers, with Navantia competing against the Aegir variant of the Tide-class tanker built by South Korea's DSME in a restricted tender competition. Navantia's proposal based on Cantabria was announced as the successful design in