HMAS Sirius (O 266) (formerly MT Delos) was a commercial tanker purchased by the Royal Australian Navy and converted into a fleet replenishment vessel to replace . She was named in honour of of the First Fleet. Launched in South Korea on 2004, and converted in Western Australia, Sirius was commissioned in 2006; three years before a purpose-built vessel would have been built, and at half the cost. The tanker was decommissioned in 2021. Construction and acquisition Delos was built at Hyundai Mipo Dockyard in South Korea. Another five ships were built to the same design, all for civilian service. She was launched on 12 April 2004, and was purchased by the Australian Government on 3 June 2004 and handed over from Hyundai on 16 June 2004, with the intention of modifying her as a replacement for for the Royal Australian Navy (RAN). Delos was leased (bareboat charter) to Teekay Shipping for operation as an commercial oil tanker until September 2005, then was taken up by Tenix Defence (which had been awarded the A$60 million conversion contract on 15 March 2005) for conversion into a replenishment vessel, which was completed 5 weeks ahead of schedule. Sirius was commissioned into the RAN on 16 September 2006, in a ceremony that included Westralias decommissioning. While HMAS Sirius is the first ship of this name to serve as part of the RAN, she is named after , the flagship of the First Fleet of British convicts sent to Australia in 1788. Sirius had a full load displacement of 46,775 tonnes, is in length, with a beam of and a draught of . Propulsion machinery consisted of a single propeller shaft driven by a single Hyundai B&W 6S 50MC diesel engine, supplemented by a bow thruster. Top speed was , and the ship had a range of at . Sirius could carry up to of fuel, including of helicopter aviation fuel, plus 240 tonnes of dry stores carried in a container deck designed for twelve intermodal containers. Modifications by Tenix included the fitting of two replenishment points (one on each side, allowing the underway replenishment of two ships simultaneously), installation of a helicopter deck aft of the superstructure, fitting of the container deck, addition of two 70-man lifeboats and two rigid-hulled inflatable boats (RHIBs) (the latter sourced from Westralia), and modification of the internal layout and equipment to bring it to naval standards. Sirius