The Peral was the first electric battery powered submarine built by the Spanish engineer and sailor, Isaac Peral, for the Spanish Navy. The first fully capable military submarine was launched on September 8, 1888. It had two torpedoes, new air systems, hull shape and propeller and cruciform external controls anticipating later designs. Its underwater speed was 3 knots (5.6 km/h) . When fully charged it was the fastest submarine yet built, with performance levels (except for range) that matched or exceeded those of First World War U-boats. In June 1890 Peral's submarine launched a torpedo under the sea. It was also the first submarine to incorporate a fully reliable underwater navigation system. However, conservatives in the Spanish naval hierarchy terminated the project despite two years of successful tests. Its operational abilities has led some to call it the first U-boat. Conception The Peral submarine was first conceived on 20 September 1884, when Lieutenant Isaac Peral y Caballero wrote a paper which would become his Proyecto de Torpedero Submarino ("Project for a submarine torpedoboat"). After several studies and experiments, and having gained support from his superiors and fellow officers, Peral exposed his idea to the Spanish navy staff. He wrote a letter to the Spanish naval minister, vice-admiral Pezuela y Lobo, the following year in September, 1885. Pezuela y Lobo

The Peral in 1888 Name: Peral Builders: Lt. Isaac Peral Operators: Spanish Navy Completed: 1888 Class & type:  Submarine Displacement: surfaced 77 tonnes submerged 85 tonnes Length: 22 m (72 ft 2 in) Beam: 2.9 m (9 ft 6 in) Draught: 2.8 m (9 ft 2 in) Propulsion: 2 x electric motors, 2 x 30 hp (22 kW), two shaft Speed - Surfaced: Submerged: 7.8 kn (14.4 km/h) 3 kn (5.6 km/h) Range -  Surfaced:  400 nmi (740 km) at 3 kn (5.6 km/h) Armament: 3 × Schwarzkopf torpedoes (14 in (360 mm)) TT (bow)

The first study consisted of human breath test in an enclosure for several hours. A room of 58 square meters was used, with an air storage cell, loaded to 79 atmospheres and a storage capacity of 0.5 m3. In addition to instruments to measure the temperature and moisture, there was a tube to re-oxygenate the air supply to the crew through a 4 mm waterproof cloak and three water buckets to maintain the moisture. Six people locked themselves inside the room; one of them had to leave an hour and quarter later, but the rest remained for a total of five hours, and the test was considered a total success.

On 21 July 1886, the new Navy Minister, rear-admiral Beranger, decided that the project would be reviewed by the Centro Técnico de la Armada (Naval Technical Center), under the responsibility of Admiral Antequera. He considered a more complete study of the actuator necessary before undertaking the construction of the hull and the electric engine. He authorized Peral to carry out all the modifications that he thought worthwhile, granting him 25,000 pesetas.

On 5 March 1887, Peral communicated that the electric motor or "depth's device", as he called it, was ready. On 17th of the same month the Commander in Chief of Cadiz, Florencio Montojo, who headed the technical committee overseeing the machine, requested budgeting for Peral's submarine.

Construction

On 25 April 1887 the submarine's construction was finally approved by the government; the keel was laid down on La Carraca on 7 October 1887, although work did not start until two weeks later. Nevertheless, the submarine had already undergone a number of modifications: Peral's original 1885 model conceived of a 61-ton submarine, 18.8 meters long, with a beam of 2.52 meters and a single 40 shp (30 kW) electric motor for a single shaft. The submarine Peral begun in 1887 had a length of more than 22 meters, a beam of 2.87 meters, a beam of 2.76 meters, two 30 shp (22 kW) electric motors geared to twin screw, and a displacement of 77 tons surfaced and 85 submerged.

Air regeneration in the interior of the submarine was accomplished by an auxiliary 6 hp (4 kW) engine, which passed the air through a Sodium Hydroxide purifier to eliminate CO2 exhaled by the crew. In addition the same pump served to inject oxygen when needed. The same engine which circulated air also drove the bailing pump.

Immersion of the submarine was obtained by means of the "depth's device" which drove two shafts of vertical axes located at both ends of the hull, moved by two 4 hp (3 kW) electrical motors to submerge or emerge the submarine and to maintain horizontal stability when immersed. The ballast tanks had a storage capacity of 8 ton, and were used to stabilize the submarine. In order to navigate, Peral used a bronze magnetic needle installed in the ceiling of the turret . The design avoided any electrical interference. He also devised a periscope, a fixed tube on the turret; and by using a series of prisms, it projected the outside world to within the submarine.

The engine-cooling system consisted of forcing compressed air stored in the submarine over the engines, and though the original project had needed 430 accumulators, the final project installed 613 with a weight of 50 kilograms. The total weight of the batteries was around 30 tons.

The top speed varied with the charge of the batteries. With one-quarter charge the submarine was able to reach 4.7 knots (8.7 km/h), with one-half 6.9 knots, with three-quarters 8.9 knots, and with the batteries completely charged the submarine was able to reach 10.9 knots (20.2 km/h). The range of the boat again depended on battery charge level; Peral calculated his original submarine could reach 132 nautical miles (244 km) at a speed of 6 knots (11 km/h).

One of the original features of the Peral was an underwater lamp, which enabled the crew to search the sea bottom. The searchlight had a range of 150 meters. 

The submarine was single-hulled, and the ballast tanks were located at the bottom of the hull, underneath the torpedo tube. This single torpedo tube was the only weapon in the submarine, with two hermetic covers on each end so the submarine could launch a torpedo submerged: firstly flooding torpedo tube, firing the torpedo, unflooding the torpedo tube, reloading, and repeating the operation. Mechanisms used for reloading were simple and fast, and the submarine had three reserves. This device, almost identical to the torpedo launchers used in submarines since then, gave the Peral the category of a strategic weapon. In order to avoid expenses, the torpedoes that the Peral launched during the trials were borrowed from torpedo boats, two from the Retamosa and one from the Barceló.

Trials The Peral was launched on 8 September 1888, sixteen days before another pioneering electric submarine, the French Gymnote. On 6 March 1889 the Peral's trials started, consisting of handling and surface navigation. On 7 August that year, the submarine submerged for the first time up to the turret; 18 days later fired the first trial torpedo (without warhead); on 5 December submerged to 7.5 m; on 25 December passed the first non-static dive test, sailing at a steady depth of 9.5 meters; and, in 1890 sailed underwater for one hour, reaching a maximum depth of 30 meters in trials.

. The Peral Submarine

Similar figures of performance were only attained about a decade later in other countries. The speed and endurance of the Peral attained WW II standards.

Preservation

In 1890 Peral was withdrawn from service, equipment removed, and the hull stored at La Carraca Arsenal. In 1913 her demolition was ordered but this was not carried out.

In 1929, Admiral Mateo García de los Reyes, first commander of the Spanish submarine forces, managed to reclaim the hull and towed it to Cartagena, putting it ashore at the submarine base. In 1965 the authorities of Cartagena succeeded in moving the hull to the Plaza de los Héroes de Cavite. It has since been restored and is now displayed at the Paseo Alfonso XII, in front of the port of Cartagena.