This class were designed in an attempt to improve the living conditions and hopefully with a capability of increased speed and extension of operational capabilities in all weather and also to operate with the Fleet.
This class was also the first to enter service with the 21 inch torpedo tube, though the Swordfish had been designed with them she did not enter service before the 'G' class. The G's were also fitted with Fessenden Underwater Sound Telegraphy.
840 hp electric motors
(2 bow), 2 beam. 1 x 3 inch gun.
Reloads: 2 x 21 inch , 8 x 18 inch
95 nm at 3 kts sm.