Saphir-class submarine (1928)

The Saphir-class submarines were 6 submarines built in France between 1926 and 1935 for the French Navy. Most saw action during World War II for the Vichy French Navy or the Free French Naval Forces. Three were captured by Italian forces but not used.

Design
66 m long, with a beam of 7.1 m and a draught of 4.3 m, Saphir-class submarines could dive up to 80 m. The submarine had a surfaced displacement of 670 t and a submerged displacement of 925 t. Propulsion while surfaced was provided by one 1300 hp diesel motor built by the Swiss manufacturer Sulzer and two 1100 hp electric motors. The submarines' electrical propulsion allowed it to attain speeds of 9 kn while submerged. Their surfaced range was 7000 nmi at 7.5 kn, and 4000 nmi at 12 kn, with a submerged range of 80 nmi at 4 kn.

The Saphir-class submarines were constructed to be able to launch torpedoes and lay mines without surfacing. The moored contact mines they used contained 220 kg of TNT and operated at up to 200 meters of depth. They were attached to the submarine's exterior under a hydrodynamic protection and were jettisoned with compressed air. The Saphir-class submarines also featured an automatic depth regulator that automatically flooded ballast tanks after mines were dropped to prevent the risk of the submarine surfacing in the middle of enemy waters.