1923 Estimates

Oberon

(ex O1)

Chatham

1926

This submarine was the prototype for a new class of patrol submarine for use in the Far East. The basic requirement was for a submarine of substantially greater endurance than the L class with the now accepted armament of six 21" bow torpedo tubes thought necessary to hit and sink a modern battleship. She was the first of what were known as “new construction” submarines and was designed by the Admiralty using not only their experience of the First World War but also of the results of their trials with surrendered German U-boats. Amongst the improvements introduced were improved living conditions, centralised diving controls, longer periscopes, increased fuel stowed externally, greatly increased diving depth and an asdic set as an integral part of the design. The Oberon was not an unqualified success. She failed to stand up to the pressure at her designed diving depth and proved complicated and unreliable. She was still considered to be operational in 1939 but not with very much confidence.

Dimensions	269.6' x 28' x 18' = 1613 tons (surface)                              1831 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. 120rounds ammo. Two Lewis guns and five rifles
Propulsion	Twin Diesel engines of 2950 HP = 15 knots.* 160 tons oil fuel = 4330 miles @ 13 kts or 8150 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.

* Actually 13.75 knots in 1939.