Isaac Peral Class Submarine (S-80plus)

Isaac Peral Class Submarine (S-80plus)

The S-80 Plus class (or Isaac Peral class) is a Spanish class of four submarines in production by the Spanish company Navantia in its Cartagena shipyard for the Spanish Navy. In common with other contemporary submarines, they feature air-independent propulsion.

They are oceanic submarines of medium tonnage with the capacity to carry out long duration missions in scenarios far from their base, acting with a minimum level of indiscretion. They will have an integrated platform control system that allows operation with a reduced endowment and a high degree of automation with remote control. The characteristics of this class of ships place them at a level close to those of nuclear propulsion.

The lead ship in the class, the Isaac Peral (S-81), was planned to enter service in 2021, and the rest in 2022-24. The S-80 class has also been offered for export.

S-80 class submarines design

The cost of construction of the four submarines is expected to be €2.2bn.

The S-80 class submarines will measure 81m in length and 7.3m in diameter. The hull of the submarine will be 61.76m long.

The surface displacement of the submarines will be 3,200t, while the submerged displacement will be 3,426t. The submarine will accommodate 32 crew members and eight transport personnel.

Development history of the S-80 class

In the 1980s France began studies for the replacement of their S-60 Daphné-class diesel submarines. The French shipyard DCNI came up with an all-new design called S-80, with a teardrop hull and new weapons and sensors, which their government 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 again rejected by the French but which was exported to Pakistan. Meanwhile, Spain faced the same problem in replacing their Daphnés, known as the Delfín class in Spanish service, as part of Plan ALTAMAR. Bazán (later Izar, and then Navantia) started on a new design but when it started to look like the S-80, it was agreed to collaborate in a joint venture based on the French S-80. This joint design was shown at Le Bourget Navale in October 1990.

The end of the Cold War meant that funding dried up and the joint venture had to wait until 1997 for their first sale – to Chile – of the new design, which was designated the Scorpène class in export markets. The same year Spain started to look again at its requirements, and in 1998 they indicated that they would buy four Scorpènes, optionally with an air-independent propulsion (AIP) system for greater endurance when submerged. A staff requirement for the S-80 Scorpène variant was completed in October 2001. This was soon overtaken by events, as the Armada (navy) became more interested in using submarines for power projection than in a more static, defensive role. This shift was codified in guidance of January 2002 from the Chief of Naval Operations and in the strategic defence review of February 2003. The new requirement called for a larger submarine with better endurance and land-attack missiles, which became known as the S-80A design. This was an AIP submarine with a hull diameter of 7.3 metres (23 ft 11 in) compared to 6.2 metres (20 ft 4 in) for the Scorpène family, a submerged displacement of around 2,400 tonnes versus 1,740 tonnes, larger rudder surfaces and a different fin position.

The Spanish government approved the purchase of four S-80A submarines in September 2003 and signed a contract with Izar on 24 March 2004. The original deal was €1,756m to design and build four submarines, about €439m per boat, but by 2010 this had increased to €2,212m (553m/boat). The plan envisaged the first boat to be delivered in 2011 but government dithering over who should supply the combat system pushed it back to 2013. In 2011 Spain’s budget crisis further delayed the first delivery until 2015, with the remaining boats being delivered at one year intervals until 2018. 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).

In May 2013, Navantia announced that a serious weight imbalance design flaw had been identified which will delay the delivery of the first submarine to the Spanish Navy until possibly 2017. Lengthening the submarine created additional buoyancy. Navantia signed on the US company General Dynamics Electric Boat to help solve the excess weight. In September 2014, the detected overweight was reported to have been resolved 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 will be lengthened by seven metres, and the displacement increased by 75 tons. As of January 2018, the intended delivery date of the first submarine is September 2022. In January 2017, it was reported that the AIP system would not be ready in time for the delivery of the first submarine. In November 2018 the companies Abengoa and Tecnicas Reunidas, said they had completed in an excellent way, their tests for the revolutionary AIP engine of the submarine. The Indian Navy considered the S-80 for its next generation of submarines under Project 75I.

Sonar suite


The S-80 submarine’s sonar suite will comprise of a cylindrical array sonar, a flank array sonar, a passive ranging sonar, and a mine and obstacle detection sonar. These facilities are being provided by Lockheed Martin. The support structures and fairings for the sonars are being provided by Goodrich.

The S-80 will also be integrated with a towed array sonar system, supplied by QinetiQ, an interception positioning system and an own noise analyser.

S-80 combat and command systems

The S-80 class will be equipped with weapons handling equipment (WHE), supplied by Babcock International, and commercial off-the-shelf technologies (COTS) jointly developed by FABA and Lockheed Martin.

The submarine will carry six torpedo launchers and 18 weapons, including mines, DM2 A4 torpedoes, MK48 torpedoes, Harpoon missiles and Tomahawk cruise missiles.

It will be fitted with satellite communication systems developed by Indra and a guidance automation unit distributed intelligence (GAUDI) autopilot system developed by Avio.

The submarine will be equipped with Aries radars, Friend or Foe identification systems (IFF) and modular Pegaso defence electronic systems supplied by Indra.

The submarine will also be enhanced by integrating non-penetrating all-weather optronic imaging systems, hoistable masts and periscopes, which will be supplied by Kollmorgen Electro-Optical and Calzoni.

Propulsion details of the S-80 class submarines

The S-80 will be powered by three diesel engines rated at 1,200kW each, a 3,500kW main electric engine, and a 300kW air independent propulsion (AIP) reactor.

The electric propulsion motors used in the submarine are 20% lighter than those used in Scorpene submarines.

The electric propulsion motors used in the submarine are 20% lighter than those used in Scorpene submarines and generate about 50% more energy compared to other submarines, while operating in the same conditions. The propulsion motors are being provided by Gamesa Electric. The propulsion system will provide a speed of 12kt on surface and 19kt when submerged.

Fuel cells for the AIP reactor will be supplied by UTC Power. The fuel cells will be fed through a bioethanol processor supplied by Abengoa. The reactor will be equipped with a carbon dioxide removal system developed by Bionet.


Type: Submarine with air-independent propulsion
  • 3,200 tonnes (3,100 long tons; 3,500 short tons) surfaced
  • 3,426 tonnes (3,372 long tons; 3,777 short tons) submerged
Length: 81.05 m (265.9 ft)
Beam: 11.68 m (38.3 ft)
Draught: 6.20 m (20.3 ft)
  • 1 shaft Etanol-AIP
  • 3 bio-ethanol engines (3 × 1,200 kW)
  • 1 electric motor (3,500 kW), 1 AIP fuel cell unit (300 kW)
  • 12 kn (22 km/h; 14 mph) surfaced
  • 19 kn (35 km/h; 22 mph) submerged
Range: 8,000 km
Endurance: 30 days in immersion
Test depth: 620 m
Complement: 32 (plus 8 troops)
Armament: 6 × 533 mm torpedo tubes with DM2A4 torpedoes and Harpoon missiles
Notes: AIP reactor autonomy: 28 days

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