Otama Class
Note: drawing contains some parts and lower hull details taken from Shipbucket.com)

Ship Characteristics

Dimensions Length 325 ft
Beam 28 ft
Draft 13.0 ft
Displacement (Surfaced) 1,950 tons
Displacement (Submerged 2,893 tons
Performance Speed (surfaced) 23.0 knots
Speed (submerged) 16 knots
Armament Torpedoes 6 21 inch.


The Otama class were the first submarines to be designed in Australia and drew very heavily on the Thames (River) class that had been transferred to the Royal Australian Navy in 1948 as part of the Imperial Gift. The basic concept of the River class was retained in that the Otamas were designed to have long range and a high surface speed. However, some of the faults in the basic River class design were addressed. These included the installation of reliable U.S.-produced submarine diesels and the reinforcement of the River class's notoriously weak stern. The hull was streamlined still further and some fittings made retractable. Overall, the performance of the new design was slightly superior on the surface (by half a knot) but much superior submerged where the Otama class could equal the German Type XXI

The major changes introduced with the Otama class were internal. The class was fitted with a new passive/active sonar system that included a keel sonar and a large above-bows array. In addition, they carried a long-range passive detection system that consisted of three blade-like receivers, two mounted before the sail and one after it. In fact, this system didn't work very well since the aftermost of the two forward blades was too close to the sail and the aft blade was between the diesel engine rooms and suffered from interference due to to auxiliary machinery housed in those compartments. Despite these limitations, the Otamas were generally considered to be a good first attempt at a submarine design

Class Members

Number Name Ordered Laid Down Launched Commissioned Fate
R-4 Otama 1953 1953 1955 1957 Decommissioned and scrapped 1971
R-5 Onslow 1954 1954 1956 1957 Decommissioned and scrapped 1972
R-6 Oxley 1955 1955 1957 1958 Decommissioned and scrapped 1973
R-7 Opunake 1956 1956 1958 1959 Decommissioned and scrapped 1974
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