Naïade-class submarine

The Naïade class was designed by Gaston Romazotti, an early French submarine engineer and director of the Arsenal de Cherbourg to a specification for a small coastal-defense submarine. They were of a single-hull design, derived from the first French submarine, Gymnote, but with a Diesel–electric powertrain.^[2] The hull was constructed of Roma-bronze, a copper alloy devised by Romazotti to resist corrosion better than steel.^[3] The submarines had a surfaced displacement of 70 long tons (71 t) and 74 long tons (75 t) submerged. They measured 23.7 metres (77 ft 9 in) long overall with a beam of 2.3 metres (7 ft 7 in) and draught of 2.6 metres (8 ft 6 in). The crew numbered nine men.^[4]

The Naïade's were equipped with a variable-pitch propeller and two auxiliary side-thrusting propellers (French: hélices auxiliaires évolueurs). On the surface, the propeller shaft was driven by two dynamos powered either by the Panhard et Levassor four-cycle benzol engine designed to produce 65 brake horsepower (48 kW) or the batteries used underwater. Speeds attained during the boats' sea trials reached up to 8.2 knots (15.2 km/h; 9.4 mph) from 104 bhp (78 kW). Underwater power for the Naïades was provided by a Société Éclairage Électrique electric motor rated at 70 shaft horsepower (52 kW) and intended to give them a maximum speed of 6 knots (11 km/h; 6.9 mph). Speeds during their sea trials were disappointing at only 5.3 knots (9.8 km/h; 6.1 mph) from 92 shp (69 kW). They were designed to have a range of 30 nautical miles (56 km; 35 mi) at 4.1 knots (7.6 km/h; 4.7 mph) submerged and 200 nautical miles (370 km; 230 mi) at 5.5 knots (10.2 km/h; 6.3 mph) on the surface. The Naïade class were armed with two single 450 millimetres (17.7 in) torpedoes located externally in Drzewiecki drop collars.^[4]

The Naïades were smaller than Romazotti's previous Morse and Français-class submarines, smaller in fact than any French submarine to that date except the pioneering Gymnote. However the Naïades had an adequate armament (two torpedoes, carried externally) and a good performance, with a better range than Romazotti's previous designs or the contemporary Farfadet class, though not as good as Narval and Sirène class.^{[citation needed]} They were considered good surface boats, with good maneuverability but erratic when submerged.^[1]