~4,100 tonnes surfaced
~4,600 tonnes submerged.
4 x 6400 hp steam turbines for ~25 knots surfaced, 2 x 2400 hp electric motors for ~9.5 knots submerged. 2 x 500 hp diesel generators for battery charging.
10 x 550mm torpedo tubes, 20 reloads.
4 x 140mm SP guns w/2500 rounds.
2 x 84mm AA guns w/300 rounds.
Test depth 90m.
Range of 25,000 km @ 10 knots surfaced, 130 km @ 4.5 knots submerged.
Upper hull armoured against destroyer-calibre gunfire w/90mm plating.
One specially designed watertight semi-submersible cutter carried in a pocket forward, able to be launched with boarding party already aboard while at periscope depth. One floatplane carried disassembled.
Crew of 109 officers and enlisted.
A follow on from the 1913 Vickers-Kaurna project for a steam powered submarine, (the Artemisiya), these much improved versions kept the high surface speed of the class, but fitted their boilers inside separate pressure hulls, permitting free-flooding of the boiler rooms, as well as keeping the crew safer from dangerous heat-buildups in the tropics. Two flotillas were built in the early 1920's, only to fall victim to the First London Naval Treaty's ban on large submarines.