Note: drawing contains some parts and lower hull details taken from Shipbucket.com)
|Displacement (Surfaced)||2,650 tons|
|Displacement (Submerged||3,930 tons|
|Performance||Speed (surfaced)||24.5 knots|
|Speed (submerged)||16 knots|
|Armament||Torpedoes||6 22.4 inch.|
The Oberon class were originally budgeted as a repeat or improved Otama class but the reality was that they were a completely new design sharing only the basic saddle tank, twin-screw design of the original Otama class. The changes made included new diesels that pushed surfaced speed up a further 1.5 knots to 24.5 knots although submerged speed remained the same. The sensor outfit was superficially the same as the Otama but, again, the differences were actually significant. the blade receivers of the passive detection system were repositioned and enlarged while the above and below water bow arrays were enlarged, the above-bow dome housing 96 rather than 64 elements while the keel dome was increased from 48 elements to 64. The most significant change though went unannounced for many years. Observers had noted two circular ports at the aft end of the upper casing. These were widely assumed to be either stern torpedo tubes or decoy launchers. In fact, they housed a reelable passive towed array. The early versions carried were very simple, little mroe advanced than the towed hydrophones used by British destroyers in 1917 but the equipment was quickly improved and by the early 1970s had become a formidable detection system.
The actual armament change was also subtle. The 21 inch torpedo tube was abandoned and replaced by a 22.4 inch tube that allowed existing 21 inch torpedoes to be launched using swim-out. The same larger tube allowed a new generation of 22.4 inch torpedoes to be developed. Finally, the Oberon class were extensively silenced making them the quietest submarines of their era. Their diesels and other machinery was rafted and sound-insulated, partly explaining their increased size.
An initial class of four submarines were ordered with a fifth being added when delays with the following P-class delayed that design. Then, when the funding and political problems of the early and mid-1960s escalated, the fifth boat was suspended and then broken up on the stocks. The first four boats had long and successful careers becoming the Australian Navy's main intelligence-gathering platforms.
|R-8||Oberon||1957||1957||1959||1960||Decommissioned and scrapped 1980|
|R-9||Omeo||1958||1958||1960||1961||Decommissioned and scrapped 1981|
|R-10||Otago||1959||1959||1961||1962||Decommissioned and scrapped 1982|
|R-11||Orange||1960||1960||1962||1963||Decommissioned and scrapped 1983|
|R-12||Oamaru||1961||1961||Suspended 1962. Broken up on stocks 1966|