[1] For surface running, the boats were powered by a single 16-cylinder 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.

[3] C9 was laid down on 20 January 1906 by Vickers at their Barrow-in-Furness shipyard, launched on 3 April 1907, and completed on 18 June.

During World War I, the boat was generally used for coastal defence and training in home waters.