The Peral was the first electric battery powered submarine. Its operational abilities has led some to call it the first U-boat

U-boat

U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

.

Conception

The Peral submarine was first conceived on 20 September 1884, when Lieutenant Isaac Peral

Isaac Peral

Isaac Peral y Caballero , was a Spanish engineer, sailor and designer of the Peral Submarine .-Career:...

 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 called Peral to Madrid

Madrid

Madrid is the capital and largest city of Spain. The population of the city is roughly 3.3 million and the entire population of the Madrid metropolitan area is calculated to be 6.271 million. It is the third largest city in the European Union, after London and Berlin, and its metropolitan...

 to have a personal interview with him. After the interview Pezuela y Lobo agreed to finance Peral's preliminary studies in Cádiz

Cádiz

Cadiz is a city and port in southwestern Spain. It is the capital of the homonymous province, one of eight which make up the autonomous community of Andalusia....

 with an initial budget of 5,000 pesetas

Spanish peseta

The peseta was the currency of Spain between 1869 and 2002. Along with the French franc, it was also a de facto currency used in Andorra .- Etymology :...

, before launching a program to build a full-scale submarine boat.

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

Actuator

An actuator is a type of motor for moving or controlling a mechanism or system. It is operated by a source of energy, usually in the form of an electric current, hydraulic fluid pressure or pneumatic pressure, and converts that energy into some kind of motion. An actuator is the mechanism by which...

 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 electric motor for a single shaft. The submarine Peral began 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 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 engine, which passed the air through a Sodium Hydroxide purifier to eliminated 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 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

Periscope

A periscope is an instrument for observation from a concealed position. In its simplest form it consists of a tube with mirrors at each end set parallel to each other at a 45-degree angle....

, 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 (9.2 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 (21.4 km/h). The range of the boat again depended on battery charge level; Peral calculated his original submarine could reach 132 nautical miles (244.5 km) at a speed of 6 knots (11.8 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

Gymnote

The Gymnote was one of the world's first all-electric submarines.Launched on 24 September 1888, she was developed in France following early experiments by Dupuy de Lôme, and, after his death, by Gustave Zédé and Arthur Krebs, who completed the project...

. On 6 March 1889 the Perals 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.

On 25 June that year the Peral made two simulated engagements on the cruiser Colón

Spanish cruiser Cristobal Colon (1887)

Cristóbal Colón was a Velasco-class unprotected cruiser of the Spanish Navy.-Technical Characteristics:Cristóbal Colón was built at La Carraca shipyard, Cadiz, Spain. Her keel was laid in 1883. She had one rather tall funnel. She had an iron hull and was rigged as a barque...

, one at day and other at night. At the daylight trial the submarine was unable to attack the cruiser, as the optical turret was spotted less than 1000 yards (914.4 m) away from the cruiser, which had 200 civilian and military guests who obviously expected to see the submarine, a fact that angered Isaac Peral. The simulated night attack was successful. The staff that evaluated the trials of the submarine submitted a report, considering its speed and range insufficient, and being especially critical about the failure of the submarine during the daylight attack and its electric motors. However, overall the report was positive, and a second submarine was ordered, again under the direction of Isaac Peral but also managed by several naval departments. Peral designed a 30-meter submarine of 130 tons, under the condition of choosing the yard where the submarine would be built and the choosing the team to build it. These conditions were not accepted by the authorities, who considered this a refusal by Peral to build the submarine. Finally they ordered Peral to return the submarine to the La Carraca yard where it was built. On 11 November 1890 a decree set the end of the projects of underwater navigation in the Spanish navy.

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

Cartagena, Spain

Cartagena is a Spanish city and a major naval station located in the Region of Murcia, by the Mediterranean coast, south-eastern Spain. As of January 2011, it has a population of 218,210 inhabitants being the Region’s second largest municipality and the country’s 6th non-Province capital...

, 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.