India signed the agreement for these submarines with Howaldtswerke-Deutsche Werft (HDW) on 11 December 1981. The agreement called for building of two submarines in West Germany, the supply of knocked-down kits for assembling two more submarines in Mazagon Dock Limited (MDL), and training for construction and logistics services. An agreement was announced in 1984 for the construction of two additional submarines in MDL, but was subsequently cancelled due to economic crisis in the late 1980s. The four submarines that were finally built form the 10th submarine squadron based at Mumbai.
The Indian Navy awarded a $151 million contract for mid-life upgrade and certification of INS Shishumar in 2018. The refit was carried out by MDL at Mumbai with technical cooperation from ThyssenKrupp Marine Systems.[3] [4] The refit was planned to be completed by 2021 with a similar upgrade for another vessel of Shishumar-class submarine to follow. The ship was expected to be delivered by 2021 but owing to Covid-19 delays the ship will now be delivered to the Indian Navy in August 2023.[5]
Similarly, a second mid-life upgrade contract was awarded to the Mazagon Dock for refit and life certification of the 2nd submarine on 30 June 2023. The completion date of mid-life upgrade and certification is 2026. The total estimated cost to be around .[6]
Total 3 ships out of 4 will undergo mid-life refit and certification, this will extend the life of the submarine by 10–15 years.[5]
| Name | Pennant | Builder | Laid down | Launched | Commissioned | Upgrade | Homeport | Note |
|---|---|---|---|---|---|---|---|---|
| S44 | Howaldtswerke-Deutsche Werft | 1 May 1982 | 13 December 1984 | 22 September 1986 | 2018 — 2023 | [7] | ||
| S45 | 1 September 1982 | 11 May 1984 | 20 November 1986 | 2023 — 2026 | ||||
| S46 | Mazagon Dock | 5 June 1984 | 30 September 1989 | 7 February 1992 | ||||
| S47 | 3 September 1989 | 21 March 1992 | 28 May 1994 | |||||
In a July 2005 interview with NDTV, V. P. Singh said that in 1987, while he was a minister, he had received a telegram from the Indian ambassador in Germany with the information that Indian agents had received large illegal commissions in the HDW submarine deal.[8] Singh informed the then prime minister Rajiv Gandhi about this and instituted an enquiry. Subsequently, this led to differences and Singh decided to resign from the cabinet.[9]