Built for RAN Oxley (ex AO1) Vickers 1927
1924 Otway (ex AO2) Vickers 1927

These two submarines were designed and built for the Royal Australian Navy by Vickers to replace the J-class which they had taken over from the Royal Navy after the First World War. They were basically the same as Oberon but with minor differences. No sooner had they arrived in Australia than there was a change in their defence policy and both boats were sold back to the Admiralty and were accepted into the Royal Navy. They, like Oberon, failed to reach their designed diving depth and proved unreliable. However they were considered to be operational in 1939 but without
much confidence.

Dimensions	275' x 27.6' x 18' = 1645 tons (surface)                              1872 tons (submerged)
Armament	Six 21" bow torpedo tubes. Two 21" stern torpedo tubes. Sixteen Mark VIII torpedoes. One 4" QF Mk III gun on an S1 mounting. 120 rounds ammo. Two Lewis guns and five rifles.
Propulsion	Twin Vickers Diesels of 3000 HP = 15.5 knots. 166 tons oil fuel = 3630 miles @ 15.5 kts or 7630 miles @ 8 kts. 1.8 tons per day on patrol. Main motors 1350 HP = 9 knots submerged. Batteries. 336 cells of 140 tons. 1.1 hrs @ 9 knots submerged.
Hull	Modified saddle tank type. Designed diving depth 500 feet. Operational diving depth reduced to 200 feet.
Complement	5 Officers and 50 men.
Detecting devices	Two 40 foot periscopes. Type 116 asdic set.