The C class was essentially a repeat of the preceding B class, albeit with better performance underwater. The submarine had a length of 142feet overall, a beam of 13feet and a mean draft of 11feet. They displaced 287LT on the surface and 316LT submerged. The C-class submarines had a crew of two officers and fourteen ratings.[1]
For surface running, the boats were powered by a single 16-cylinder 6000NaN0 Vickers petrol engine that drove one propeller shaft. When submerged the propeller was driven by a 300hp electric motor.[1] They could reach 12kn on the surface and underwater. On the surface, the C class had a range of 910nmi at .[2]
The boats were armed with two 18-inch (45 cm) torpedo tubes in the bow. 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]
C15 was laid down on 7 December 1906 by Vickers at their Barrow-in-Furness shipyard, launched on 21 January 1908, and completed on 1 April. During World War I, the boat was generally used for coastal defence and training in home waters. The boat torpedoed in the English Channel on 3 November 1917. She was sold for scrap on 28 February 1922.