[1] For surface running, the boats were powered by a single 12-cylinder[2] 600-brake-horsepower (447 kW) Vickers petrol engine that drove one propeller shaft.

On the surface, the C class had a range of 910 nautical miles (1,690 km; 1,050 mi) at 12 knots (22 km/h; 14 mph).

They could carry a pair of reload torpedoes, but generally did not as they would have to remove an equal weight of fuel in compensation.

HMS C27 along with the trawler Princess Louise (ex-Princess Marie Jose) sank U-23 in the Fair Isle Channel between Orkney and Shetland on 20 July 1915 using the U-boat trap tactic.

The boat was scuttled on 5 April 1918 outside Helsingfors (now Helsinki) south of the Harmaja Light (Gråhara) to avoid seizure by advancing German forces.