Brazil prepares two Tupi-class submarines as targets for future SINKEX sinking exercise.

The Brazilian Navy plans to use two retired Tupi-class submarines, Timbira (S32) and Tapajó (S33), as naval targets in a future SINKEX sinking exercise.

The Brazilian Navy is preparing two decommissioned Tupi-class submarines, Timbira (S32) and Tapajó (S33), for use as naval targets in a future SINKEX sinking exercise. The Timbira and Tapajo are currently moored at the Arsenal de Marinha do Rio de Janeiro, and show visual markings consistent with previous Brazilian vessels targeted during such exercises.
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The Tupi-class is based on the German Type 209/1400 submarine, and includes four boats: the Tupi (S30), the Tamoio (S31), the Timbira (S32), decommissioned on February 17, 2023, and the Tapajó (S33), withdrawn on August 11, 2023. (Picture source: Brazilian Navy)

On March 8, 2026, Poder Naval indicated that the Brazilian Navy is preparing two retired Tupi-class submarines, Timbira (S32) and Tapajó (S33), for use as naval targets in a future SINKEX exercise. Both hulls are currently moored at the Arsenal de Marinha do Rio de Janeiro (AMRJ), near the shipyard infrastructure where they were originally constructed for the Brazilian submarine force. During early 2026, the submarines began to display highly visible markings, consisting of a yellow-painted bow and a red-painted stern, a color pattern previously used on Brazilian naval vessels selected for live-fire sinking exercises, such as the frigate Greenhalgh (F46).

The two submarines have remained at the AMRJ pier since leaving the Almirante Jardim dry dock in mid-2025 after the Brazilian Navy removed reusable equipment to sustain operational submarines still in service. The preparation of the submarines suggests that Brazil intends to conduct a SINKEX involving former underwater combatants rather than a surface ship alone. A SINKEX, short for sinking exercise, is a naval live-fire training activity in which a decommissioned vessel is deliberately destroyed using operational weapons such as anti-ship missiles, torpedoes, air-launched munitions, or naval gunfire.

The objective is to provide realistic combat conditions for naval crews while simultaneously observing the structural response of a real warship under attack. Because submarines possess thick pressure hulls, internal watertight compartments, and dense equipment arrangements, they represent a different structural target than surface combatants and therefore generate distinct damage patterns during weapon impact. Using retired submarines as targets can therefore support weapon evaluation, crew training, and tactical development for anti-submarine or anti-ship engagements. 

The first of the two Type 209 derivatives, the Timbira (S32), served as the third submarine of the Tupi-class and was formally decommissioned on February 17, 2023, after 27 years of service. The submarine was built at the Arsenal de Marinha do Rio de Janeiro, laid down on September 15, 1987, launched on January 5, 1996, and commissioned on December 16, 1996. The boat displaced 1,170 tons when surfaced and 1,460 tons when submerged, measured 61.2 meters in length with a beam of 6.25 meters and a draft of 5.5 meters, and carried a crew of about 30 personnel. Its operational tasks included maritime surveillance, anti-surface warfare, and intelligence missions within Brazil’s extensive maritime jurisdiction along the Atlantic coastline.

The Tapajó (S33), the fourth and final submarine of the same class, followed a similar operational trajectory within the Brazilian fleet. Built at the same Rio de Janeiro naval shipyard, the Tapajó entered service on December 21, 1999, after its construction under Brazil’s domestic submarine assembly program. The submarine remained active for more than two decades and was officially withdrawn from operational service in August 2023. Its retirement occurred several months after Timbira left the fleet, reflecting a broader restructuring of the Brazilian submarine inventory. Both vessels were subsequently stripped of equipment and spare parts that could be reused to maintain the operational availability of the Tupi (S30) and the Tikuna (S34).

The latter submarine, although categorized as a separate class, incorporates multiple design similarities that allow certain systems and components to remain compatible with earlier boats. The Tupi-class itself is a Brazilian subvariant of the German Type 209/1400 diesel-electric submarine, a widely exported submarine family developed by the German shipbuilder Howaldtswerke Deutsche Werft. The class entered Brazilian service between 1989 and 1999 with four submarines: Tupi (S30), Tamoio (S31), Timbira (S32), and Tapajó (S33). The first boat, the Tupi, was built in Kiel, Germany, and commissioned in May 1989, while the remaining three submarines were constructed in Rio de Janeiro as part of a technology transfer process that expanded Brazilian shipbuilding capabilities.

This program required significant industrial adaptation within the Arsenal de Marinha do Rio de Janeiro, including specialized assembly halls, updated workshops, and a floating dock to support submarine construction and integration. Pressure hull sections were manufactured domestically by Nuclebrás Equipamentos Pesados and transported to the naval shipyard for final assembly. The Tupi-class submarines measure 61.2 meters in length with a beam of 6.2 meters and a draft of 5.5 meters. Surface displacement ranges between 1,170 and 1,260 tons, increasing to about 1,440 tons when submerged.

The boats are powered by a diesel-electric propulsion system composed of four MTU 12V493 TY60 diesel engines rated at about 800 hp each, coupled to generators and a single electric propulsion motor producing roughly 5,000 hp. Propulsion is transmitted through one shaft connected to a multi-bladed propeller. This arrangement allows the submarines to reach speeds of about 11 knots while surfaced or snorkeling and up to 21.5 knots while submerged. Operational endurance reaches roughly 50 days, while cruising range can reach 8,200 nautical miles at an economical speed of 8 knots on the surface. The maximum diving depth is about 250 meters, providing adequate operational flexibility for patrol missions in deep Atlantic waters.

The combat system of the Tupi-class centers on eight 533 mm torpedo tubes located in the bow section. These tubes can launch up to 16 torpedoes, typically the Marconi Mk 24 Tigerfish wire-guided torpedoes designed for anti-ship and anti-submarine engagements. The Tigerfish uses acoustic homing guidance, carries a warhead weighing 134 kilograms, and operates at speeds ranging from 25 knots in passive mode to as much as 50 knots in active seeker mode. The submarines can alternatively carry naval mines instead of torpedoes, depending on mission requirements. Onboard sensors include the Atlas Elektronik CSU-83/1 sonar system capable of both passive and active search modes, providing 360-degree underwater detection coverage.

Additional systems include the Thomson-CSF Calypso III navigation radar, the DR-4000 electronic support measures receiver, and the Ferranti KAFS-A10 weapon control system responsible for managing torpedo launches and sensor integration. A SINKEX exercise involving these submarines would follow a structured preparation and execution process typical of naval live-fire sinking events. Before being used as targets, retired vessels undergo extensive environmental preparation during which fuels, oils, electrical equipment, and hazardous materials are removed to reduce environmental impact.

The stripped hull is then towed to a designated area at sea located far from commercial shipping routes and coastal waters. Regulations typically require deep water locations exceeding 1,000 fathoms, equivalent to roughly 6,000 feet, and distances of at least 50 nautical miles from land. Once the target reaches the designated zone, naval forces engage it using operational weapons until the vessel sinks. Aircraft, surface combatants, and submarines may participate simultaneously or sequentially, allowing forces to practice coordinated strikes under realistic combat conditions.

Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.