K8 displaced 1800LT when at the surface and 2600LT while submerged. It had a total length of 338feet, a beam of 26feet, and a draught of 20feet. The submarine was powered by two oil-fired Yarrow Shipbuilders boilers each supplying one geared Brown-Curtis or Parsons steam turbine; this developed 10,500 ship horsepower (7,800 kW) to drive two 7inchesft6inchesin (ftin) screws. Submerged power came from four electric motors each producing 350to. It was also had an 800hp diesel engine to be used when steam was being raised, or instead of raising steam.[1]
The submarine had a maximum surface speed of 24kn and a submerged speed of 9to.[2] It could operate at depths of 150feet at 2kn for 80nmi. K8 was armed with ten 18inches torpedo tubes, two 4inches deck guns, and a 3inches anti-aircraft gun. Its torpedo tubes were four in the bows, four in the midship section firing to the sides, and two were mounted on the deck in a rotating mounting. Its complement was fifty-nine crew members.[2]