The Nistar class is a series of two diving support vessels being built by Hindustan Shipyard (HSL) for the Indian Navy.^[2] The deal was signed on 20 September 2018 with the delivery of the ships is scheduled to commence from July 2023. The primary role of the vessels to support the Indian Navy's submarine fleet and meet various operational requirements such as submarine rescue, deep sea diving operations, sustained patrolling, non combatant evacuation operations and search and rescue (SAR).^[1]

Quick Facts Class overview, General characteristics ...

Nistar at launch ceremony
Class overview
Builders	Hindustan Shipyard (HSL)
Operators	Indian Navy
Cost	₹2,392.94 crore (equivalent to ₹32 billion or US$400 million in 2023) ₹1,196.47 crore (equivalent to ₹16 billion or US$200 million in 2023) per unit (FY 2018)
Planned	2
Completed	2
General characteristics
Type	Diving support vessel
Displacement	9,350 t (9,202 long tons)[1]
Length	118.4 m (388 ft 5 in)[1]
Beam	22.8 m (74 ft 10 in)[1]
Propulsion	2 x diesel engine
Complement	1 x Deep-submergence rescue vehicle[1]
Sensors and processing systems	Navigation radar 2 x BEL Lynx-U2 2 x EOIRST
Electronic warfare & decoys	1 x EW Suite
Armament	2 × 30 mm/65 AK-630 CIWS
Aircraft carried	1 × 15 t (15 long tons) helicopter.

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The Nistar-class project is a series of two diving support vessels being built to support Indian Navy's expanding submarine fleet. These ships will act as a mother ship to the recently acquired deep-submergence rescue vehicle (DSRV) for rescuing and aiding submarines in need. To aid in its submarine operation, the Indian Navy signed a contract with the Hindustan Shipyard (HSL) to indigenously design, develop and manufacture these ships on 20 September 2018.^[3] Initially, the design of the vessel was limited to 7,650 t (7,529 long tons) which later increased to 9,350 t (9,202 long tons).^[4][5][6]

The deal that was signed in September 2018 had a value of ₹2,392.94 crore (equivalent to ₹32 billion or US$400 million in 2023). The aim was to deliver the first vessel within 36 months of signing the deal. However, there was considerable delay due to the COVID-19 pandemic with the launching of the ships done in September 2022 and the first delivery expected in July 2023, this tantamount to a delay of two years.^[7]

The project was awarded to HSL on a nomination basis to improve the financial standing of the shipyard. HSL began construction activities for the project in 2019.^[8]

HSL started the construction activities months after signing the deal. The beleaguered shipyard won this project on a nomination basis to bolster its financial position.^[8] The first ship (Yard-11190) was laid down on 28 December 2019, a year after signing the deal whilst the keel of the second ship (Yard-11191) was laid down three months later on 23 March 2020.^[9]

The contract obligated the shipyard to deliver the ships within 36 months from signing the deal but there has been considerably delays owing to the COVID-19 pandemic and subsequent lock down in India. Both the ships were concurrently launched on 22 September 2022.^[1]

A minimum delay of a year was expected with the first ship, which is expected to be delivered in July 2023 while the second ship will be delivered six months later, around January 2024. Owing to this delay, the Indian Navy has released a Request for Information (RFI) to lease a mother ship to operate their deep-submergence rescue vehicle (DSRV).^[10]

The ship will have at least 80% indigenous content contributing significantly to the Atmanirbhar Bharat mission of the Government of India and further bolstered the Indian economy.^[11]

As of December 2022, 46% of the physical construction has been complete on both the ships with deliveries expected to be completed by 2024.^[12]

The ships will have a displacement of 9,350 t (9,202 long tons) which has considerably increased from the contracted weight of 7,650 tonnes (7,529 long tons). The reason for the substantial increase in weight has not been disclosed but it can be corroborated to increased role of the ship. The length of 118.4 metres (388 ft 5 in) and a beam of 22.8 m (74 ft 10 in). The diving support vessels (DSVs) are first of the kind ship, indigenously designed and built at HSL for the Indian Navy.^[1]

The ship has been designed by HSL with design consultancy from Vik-Sandvik design similar to the INS Dhruv, another specialty ship manufactured by HSL.^[13][14][15]

These ships will be able to perform carry out submarine rescue, deep sea diving operations along with search and rescue missions, sustained patrolling and helicopter operations at the sea.^[16]

• Future of the Indian Navy