Navantia begins AIP system testing on Spanish Navy’s S-83 submarine

June 18, 2026, by Fatima Bahtić

Spanish shipbuilding company Navantia has begun testing of the air-independent propulsion system (AIP) incorporated into the section of the Spanish Navy’s submarine S-83 Cosme García, the third unit in the S80 series.

The section of S83 carrying the AIP is located in a special test facility at the Cartagena shipyard, known as IPS3, where a multidisciplinary task force from the Submarine Business has carried out all the necessary checks to begin testing.

These final tests are starting after all prior installation work on the various pieces of equipment required for their proper execution has been completed.

According to Navantia, the tests will make it possible to carry out the necessary adjustments to the system in its actual location before joining the 12-meter-long, approximately 400-ton section to the rest of the submarine’s pressure hull.

Testing of the AIP in its section has begun with the first loading of liquid oxygen and bioethanol, from which the system produces hydrogen to fuel its hydrogen fuel cell and propel the submarine while submerged. It is therefore a third-generation AIP system, that is, it does not carry stored hydrogen, but generates it on demand from a liquid fuel.

Navantia noted that air-independent propulsion will give the S80 submarines the ability to operate submerged for weeks rather than days, the period for which current conventional submarines equipped with lead-acid batteries can remain underwater.

The AIP will undergo the checks set out in the program’s systems engineering manual on a unique test bench capable of simulating both the bow and stern of the submarine as well as real operating conditions, including diving depth and the submarine’s forward speed.

This will make it possible to carry out functional adjustments and demonstrations, including power generation with the AIP under various operating conditions, helping to optimize the planned schedule for testing the system in the harbour.

The testing process on board the S83 section represents a new milestone for the AIP, with S82 undergoing harbour trials and S83 and S84, the next two units, under construction at the Cartagena shipyard.

Spanish Navy’s second S-80 submarine Narciso Monturiol hits the water

Vessels

Navantia’s S-80 program involves the construction of four next-generation submarines for the Spanish Navy.

Thanks to the air-independent propulsion system (AIP), these vessels can generate electrical power while submerged, using oxygen and bioethanol stored on board, enabling them to operate for extended periods without surfacing.