The modern Italian Navy still makes use of the Cold War-era Sauro-class diesel-electric attack submarines as part of its undersea fleet. The group consisted of eight total boats at peak usage with the final four boats built still in operation (as of November 2017) and the first four having been retired. The class entered service in 1980 and succeeded the mixed collection of Toti-, Tang- and Tench-class boats. They, themselves, were eventually succeeded by the Todaro-class (the joint German-Italian Type 212-based group).
Boats of the Sauro-class included lead ship Nazario Sauro (S-518), Carlo Feccia di Cossato (S-519), Leonardo da Vinci (S-520), Guglielmo Marconi (S-521), Salvatore Pelosi (S-522), Giuliano Prini (S-523), Primo Longobardo (S-524) and Gianfranco Gazzana Priaroggia (S-525). Sauro and Cossato were Batch I boats while da Vinci and Marconi were Batch II boats. Pelosi and Prini made up Batch III and Longobardo and Priaroggia were the two Batch IV boats.
The class was commissioned from 1979 (Cossato) until 1993 (Priaroggia). Nazario Sauro was laid down on June 26th, 1974 and launched on October 9th, 1976. She was not commissioned until March 1st of 1980, allowing Cossato to be commissioned first on November 5th, 1979.
The Sauro-class was manufactured in four batches (I, II, III and IV) with three being more distinct (I, III and IV). Batches I and II were given displacements of 1,456 tons surfaced and 1,641 tons submerged. Batch III followed with 1,476 tons surfaced and 1,662 tons submerged. Batch IV had a 1,653 ton surface weight and 1,862 submerged weight. Lengths varied between the three as well with batches I and II being 63.85 meters long, Batch III following with a 64.3 meter length and Batch IV having a 66 meter length. Beams measured 6.8 meters for all of the class. Draught was increased progressively between the three from 5.3 meters to 5.6 meters and, ultimately, 6.3 meters.
Its design included a rounded, yet blunt, bow section. The sail was positioned near midships. The sides of the hull bulged and the hull as a whole tapered to the rear where the tailplanes and propellers were featured. One of the more interesting physical assets of the boat was its use of three dive planes - one fitted at the bow, the other on the sides of the sail and the other at the aft section. Aboard were a crew of seven officers and forty-four enlisted personnel arranged in shifts. The Batch I and II boats carried SMA SPS-704 series radar and the Elsag-USEA IPD70/S sonar system. Batch III and IV introduced the SMA MM/BPS 704-V2 radar fit and the STN Atlas Elektronik-ISUS 90-20 series sonar fit. All of the series carried electronic warfare and decoy equipment common to attack submarines.
All the boats were powered by a diesel-electric propulsion scheme headlined by a Grandi Motori Trieste (GMT) diesel unit. Batches I, II and III all carried a Magneti Marelli 2,686 kiloWatt electric motor and Batch IV was completed with an ABB electric motor. In either case, the boats could expect to make headway at 12 knots when surfaced and up to 19 knots when submerged (not particularly fast by modern standards). Range was out to 2,500 nautical miles (2,900 miles) and the hulls were tested to depths of 300 meters.
Armament of all the batches was 6 x 533mm torpedo tubes with 12 reloads carried and provision for up to 24 naval mines (the latter in lieu of torpedoes). Batches I and II relied on the Whitehead A-184 torpedo series while batches III and IV used the upgraded Whitehead A-184 Mod 3 series torpedoes.
As of November 2017, the four boats of the class still in commission were Pelosi, Prini, Longobardo and Priaroggia.