HMAS Orion

HMAS Orion (S 61) was an Oberon class submarine of the Royal Australian Navy (RAN). One of six submarines ordered by the RAN during the 1960s, Orion, named after the constellation in a break from ship-naming tradition, was built in Scotland and commissioned in 1977.

Orion was decommissioned in 1996, marked for disposal in 2003, and broken up for scrap in 2006. Several sections of the submarine remain intact as memorials and museum pieces.

Design and construction
The Oberon class was based heavily on the preceding Porpoise class of submarines, with changes made to improve the vessels' hull integrity, sensor systems, and stealth capabilities. Eight submarines were ordered for the RAN, in two batches of four. The first batch was approved in 1963, and the second batch (including Orion) was approved during the late 1960s, although two of these were cancelled before construction started in 1969, with the funding redirected to the Fleet Air Arm. This was the fourth time the RAN had attempted to establish a submarine branch.

The submarine is 295.2 ft long, with a beam of 26.5 ft, and a draught of 18 ft when surfaced. At full load displacement, she displaces 2,030 tons when surfaced, and 2,410 tons when submerged. The two propeller shafts are each driven by an English Electric motor providing 3,500 brake horsepower and 4,500 shaft horsepower; the electricity for these is generated by two Admiralty Standard Range supercharged V16 diesel generators. The submarine could travel at up to 12 kn on the surface, and up to 17 kn when submerged, had a maximum range of 9000 nmi at 12 kn, and a test depth of 200 m below sea level. When launched, the boat had a company of 8 officers and 56 sailors, but by the time she decommissioned, the number of sailors had increased to 60. In addition, up to 16 trainees could be carried.

The main armament of the Oberons consisted of six 21 in torpedo tubes. The British Mark 8 torpedo was initially carried by the submarine; this was later replaced by the wire-guided Mark 23. Between 1977 and 1985, the Australian Oberons were upgraded to carry United States Navy Mark 48 torpedoes and UGM-84 Sub Harpoon anti-ship missiles. As of 1996, the standard payload of an Australian Oberon was a mix of 20 Mark 48 Mod 4 torpedoes and Sub Harpoon missiles. Some or all of the torpedo payload could be replaced by Mark 5 Stonefish sea mines, which were deployed through the torpedo tubes. On entering service, two stern-mounted, short-length 21 in torpedo tubes for Mark 20 anti-submarine torpedoes were fitted. However, the development of steerable wire-guided torpedoes made the less-capable aft-firing torpedoes redundant; they were closed off, and later removed during a refit.

Orion was laid down by Scotts Shipbuilding and Engineering Company at Greenock, Scotland on 6 October 1972, launched on 16 September 1974, and commissioned into the RAN on 15 June 1977. The submarine was due to enter service in 1975, but faulty high-power electrical cabling had been installed in Orion and sister boat HMAS Otama; stripping out and replacing the cabling delayed each submarine's construction by two years. The delay meant that the two boats could be fitted with Micropuffs rangefinding sonar during construction, and have additional electronic surveillance equipment installed. Orion's name comes from the constellation Orion: although a name with strong links to the Royal Navy (with six vessels operating as HMS Orion), this was a break from the RAN's traditional use of the names of explorers and pioneers for submarines. The submarine's motto of "Orbe Circumcincto" (Latin for "All around the world") refers to the visibility of the constellation from any point on Earth.

Operational history
In 1987, Orion was awarded the Gloucester Cup, for being the RAN vessel demonstrating the greatest overall efficiency over the previous twelve months. Orion was the last submarine to receive the Cup until 2005, when it was presented to the Collins class submarine HMAS Rankin (SSG 78). Like a number of other Oberon class submarines, Orion carried out many special operation deployments during her service which qualified those crew members for the Australian Service Medal, with Special Operations clasp. Conducted between 1978 and 1992, these operations involved intelligence-gathering missions off the coasts of Vietnam, Indonesia, China and India, primarily targeting the Soviet Navy during the Cold War.

Decommissioning and fate
Orion paid off into reserve at Garden Island, Western Australia in 1996. She remained there for several years, until she was marked for disposal as scrap in September 2003. Efforts to hand her over to a State Government for preservation as a museum ship or sinking as a dive wreck failed, and submissions for disposal companies were closed off on 6 August 2004. The submarine was sold off for scrapping, and was broken up by Tenix at Henderson, Western Australia in December 2006. The fin was given to the City of Rockingham and is now mounted as a permanent memorial at Rockingham Naval Memorial Park. The port propeller was donated to the Western Australia Maritime Museum.

In November 2011, authorisation was granted to establish a new Australian Naval Cadets unit in Jindabyne, New South Wales, named New Training Ship (NTS) Orion after the submarine. In addition to the name, the cadet unit will use Orion's badge and motto.