Oberon was the first submarine to carry ASDIC - a device originally designed under the auspices of the Allied Submarine Detection Investigation Committee to detect submarines.
However, ASDIC, the forerunner of SONAR, was put to good use by submariners against surface targets and took over from the hydrophone which was unable to measure, with any accuracy, the speed, course or distance of an enemy vessel.
On their delivery voyage to Australia in 1928, Oxley and Otway encountered very severe weather in the Bay of Biscay which badly strained their engine columns, forcing them to remain in Malta for several months whilst British experts repaired the damage. After useful service in the Royal Australian Navy, the two vessels were transferred to the Royal Navy in 1931.
In 1925, the need for a new programme of Overseas Patrol Submarine construction resulted in the Odin Class. This class was 13 feet longer than the Oberons, owing, primarily, to a 7ft 6in increase in the engine room length. Odin was approved by the Board in August 1926, and was the first of a class of six: the others being Oswald; Osiris; Otus; Olympus and Orpheus.
In the 1927 Programme, six Parthian Class submarines were ordered (Parthian; Perseus; Poseidon; Proteus; Pandora and Phoenix), and in the following year six Rainbow Class (Rainbow; Regent; Regulus; Rover; Rupert and Royalist) were also ordered. Of the latter, Rupert and Royalist were subsequently cancelled. Although slightly larger than the O boats, the main particulars of these two classes were practically the same. But, in an attempt to make living conditions more pleasant on long surface passages to the Far East, the Rainbow Class were fitted with a galley on the upper deck and a shower in the conning tower.
