of the
Agosta-class submarine (S-70). It was in service until 2020.
Galerna (S-71) is still active. In the 1980s, France began studies for the replacement of their
S-60 Daphné-class diesel submarines. The French shipyard DCNI (
Direction des Constructions Navales International) came up with an all-new design called S-80, with a
teardrop hull and new weapons and sensors, which the French government ultimately decided not to fund. DCNI then proposed a cheaper option called the S-90B, an
S-70 Agosta-class submarine with limited improvements, which was rejected by the French but exported to Pakistan. which was designated the in export markets. The same year Spain started to look again at its requirements, and in 1998 they indicated that they would buy four , This was soon overtaken by events, as the Armada (Spanish Navy) became more interested in using submarines for
power projection than static defensive role. The original deal was €1,756M to design and build four submarines, by 2010 (€553M per boat). The plan envisaged the first boat to be delivered in 2011 but government dithering over the company supplying the combat system pushed it back to 2013. Construction of S-81 began on 13 December 2007. In January 2012 the names were announced, honouring three engineers who made submarines and the first commander of Spain's submarine force respectively -
Isaac Peral (S-81),
Narciso Monturiol (S-82),
Cosme García (S-83) and Mateo García de los Reyes (S-84). By May 2013, with over of the project's US$3 billion budget for the four submarines spent, an overweight issue was discovered and eventually made public. Navantia engineers had miscalculated the weight of the submarines by some of the total 2,000 tonne mass of the submarines, more than enough to sink the submarines if not fixed. Navantia announced the issue would delay the delivery of the first submarine to the Spanish Navy until at least 2017. That date proved to be optimistic. Lengthening the submarine created additional
buoyancy. Navantia signed on the US company
General Dynamics Electric Boat to help solve the excess weight design issue. In September 2014, the overweight issue was reported to have been resolved in design changes and the construction work to be ready to resume in late October 2014. In November 2014, Navantia again reported having completed the redesign work to address the problem of overweight. In all, the hull would be lengthened by , and the displacement increased by 100 tons. , the intended delivery date of the first submarine was to be September 2022, but this was not achieved. At the time of the boat's launch in 2021 it was indicated that the plan was for the first boat to start sea trials in 2022 and be delivered in 2023.
Isaac Peral started sea trials in mid-2022, and completed its first static dive in March 2023. In January 2017, it was reported that the air-independent propulsion system would not be ready in time for the delivery of the first submarine. In November 2018 Abengoa and Tecnicas Reunidas companies stated that the test for a new-type AIP engine of the submarine were successful. The
Indian Navy considered the S-80 for its next generation of submarines under
Project-75 class- submarine. On November 30, 2023, the first unit of the class, the S-81, entered service with the Spanish Navy. The Spanish government claims that S-81 is ready to join international exercises and S-82 will float in July 2025, though a strike led by the
CSIF union could delay it. The workers complain about lower salaries than in other Navantia workplaces. Out of 2,127 companies involved in the project, around 850 are Spanish. The funding however does not necessarily end mainly abroad. == Combat systems ==