For decades since the Cold War period (1947-1991), German shipbuilding has offered some form of diesel-electric attack submarine for export to interested parties. The line has evolved considerably from the Type 201 (Germany's first post-World War 2 submarine) of the 1960s, to the Type 214 of the 2000s. In-between was the Type 209/1100 which went on to be adopted by many foreign navies - from Argentina and Brazil to South Africa and Turkey.
India became another taker which committed to four of the type in a December 1981 agreement with Germany and has operated these under the "Shishumar-class" name. These were longer and displaced heavier than other Type 209s in the series while also having an integrated crew escape sphere. However, after some time with the boats, an option for two additional boats (though initially agreed upon in 1984) was ultimately not exercised by the Indian Navy due to changing doctrine/requirements. Instead three French-originated Scorpene-class boats were chosen for procurement in 1999.
The boats of the Shishumar-class taken into service became lead-ship INS Shishumar (S44), INS Shankush (S45), INS Shalki (S46), and INS Shankul (S47). The first two boats were built in Germany by Howaldtswerke-Deutsche Werft (of Kiel) with the last two built at the Mazagon Dock Shipbuilders Ltd shipyard in India (these from premade components delivered from Germany). All remain in active service as of this writing (January 2019) and homeport out of Mumbai.
In terms of the diesel-electric submarine classes available to the modern Indian Navy, the Shishumar-class falls behind both the newer Kalvari-class and quantitatively larger Sindhughosh-class boats (both detailed elsewhere on this site). While the Sindhughosh boats have greater displacement (3,400 tons), the Kalvari-class (2,000 tons) is of more modern design and has, on paper, directly succeeded the Shishumar-class. It represents a planned six-strong group which has seen three already completed, three under construction and one in active service (2019).
In regards to the Shishumar-class, lead boat INS Shishumar (S44) was commissioned on September 22nd, 1986. She displaces 1,450 tons surfaced and 1,850 tons submerged and has an overall length of 211 feet, a beam of 21 feet, and a draught of 20 feet. Installed power is from 4 x Diesel-electric motors outputting 2,400 horsepower each, 1 x Siemens electric motor of 4,600 horsepower output, 4 x Siemens alternators of 2,400 horsepower each, and a single shaft astern. Maximum surfaced speeds reach 11 knots while submerged travel caps at 22 knots. Range is out to a healthy 8,000 nautical miles. The hull has been tested to depths of 850 feet (260 meters) giving the boat a strong deep-water capability.
Aboard is a crew complement of forty that includes eight officers (the entire crew can escape via the integrated emergency escape sphere - which is pressure rated to the exact specifications as the hull proper, holds an 8-hour oxygen supply, and its own communications system). Armament is 8 x 533mm (21") torpedo tubes at the bow and carries six to fourteen reloads (from the German wire-guided, active-passive AEG-SUT Mod 1 torpedo family). An external mine-carrying/dispensing capability is also built-in (a standard of the German boat design series). Up to 24 naval mines can be hauled in a single sortie.
Its design is largely standard and conventional for the period. The hull is well-contoured as expected and the sail sits at midships. The tailplane arrangement is of a basic cruciform pattern with the propeller unit extended out beyond the planes. The dive planes are positioned on the hull as opposed to the sail. A single, central bulkhead is used internally.
Onboard electronics consist of the Calypso surface-search radar, the CSU 83 active/passive hull-mounted sonar, the DUUX 5 passive ranging sonar, the Librascope Mk.1 Fire-Control System (FCS), AR700/Sea Sentry ESM, and C303 acoustic decoy system.
In 1999, Shishumar began a mid-life upgrade with new French sonar and an Indian data processing suite. Sister boats followed in modernization. In September of 2018, Thyssenkrupp of Germany was awarded a $151M program to refit the Indian submarine. The class will now be able to support the American Harpoon Block II anti-ship missile series as a standard weapon fit.