Gessler
ACCESS: Confidential
- Joined
- 30 June 2026
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Starting a thread to track this project. The current program calls for a 6-boat fleet, funding for the first 2 of which was granted in October 2024 (~$4.8 billion).
A bit of background: It probably serves to know that India's Arihant-class SSBN (pursued under the Advanced Technology Vessel or ATV program) originally started off as a project meant to build SSNs. It was only later that the decision was made to convert the program into an SSBN effort, following the 1998 nuclear tests and subsequent full-fledged weaponization of the nuclear capability that was initially demonstrated back in 1974 but kept in a dormant/non-weaponized state till the late 1990s, when it became clear that Pakistan was on the brink of weaponizing its own. A second-strike capability delivered via SSBN was seriously considered at that point, and took precedence over an SSN, which would have primarily been an instrument of sea-denial.
Now with 3 Arihant-class SSBNs operational (including one of a larger sub-class unofficially referred to Arihant Stretch), the SSN program is back at the fore. But it's not the same boat as once thought.
Cabinet Committee on Security (CCS) originally granted approval for the program (then known as Project-75A) in 2015, at that point the vessel was described as a 6,000-ton design (unclear if talking about surfaced or submerged displacement, but likely surfaced). A lot has changed between then and the funding grant in 2024, possibly reflecting in the program designation changing to Project-77.
This tweet summarizes what is known about the program (as of mid-2026), I've pasted the text below just in case it's deleted later:
View: https://x.com/Parthu_Potluri/status/2067512983241244782?s=20
What is CONFIRMED by reliable sources so far:
1. It will indeed displace around 10,000 tons (one figure quoted by an older source states a very specific 9,800-ton figure). So very much in the league of Russia's Yasen, China's future Type-095 & upcoming SSN-AUKUS boats, and significantly bigger than UK's Astute, France's Suffren or the earlier blocks of US' Virginia-class boats.
2. It will be powered by a 190-200 megawatt PWR known as CLWR-B2. A shore-based prototype of which is known to have been in existence at least as of 2018. (Comment: This will be the same reactor that goes on the S-5 class SSBNs as well).
3. It will have VLS capability. Described as having "close to a dozen" VLS cells of the 'large' variety, so would be capable of launching likes of BrahMos/future Scramjet-based Hypersonics & possible ASBMs/HGVs.
4. It will be a double-hulled design, similar in that regard to Russia's design philosophies.
What has NOT BEEN CONFIRMED so far:
5. Whether it will have an X-form rudder or conventional cross-form rudder/tail planes.
6. Whether Nuclear-Electric Propulsion (NEP), aka Turbo-Electric Drive will be implemented or not.
7. Whether the boat will have a Pump-Jet Propulsor (PJP) or not. The PJP & NEP implementations might be tied to each other, and will have implications on whether we follow the Russian operational doctrine of speed over stealth or if we choose to go with Western doctrine. This is the most interesting part to look forward to as Pumpjet & NEP are much more likely to find application on the S-5 SSBN program, which is in a much more advanced stage than the SSN (first 2 boats already in construction). So we can be relatively certain that whether we put it on the SSN or not might come down to doctrinal choices.
What has not been confirmed, but is EXTREMELY LIKELY nevertheless:
8. It will make use of conformal sonars. Especially a Conformal Bow Array (CBA) along with flank arrays integrated into the hull. Provision of towed array will anyway be there.
9. It will make use of non-hull penetrating optronic & other radiofrequency masts, a technology we've already commercialized for production.
A bit of background: It probably serves to know that India's Arihant-class SSBN (pursued under the Advanced Technology Vessel or ATV program) originally started off as a project meant to build SSNs. It was only later that the decision was made to convert the program into an SSBN effort, following the 1998 nuclear tests and subsequent full-fledged weaponization of the nuclear capability that was initially demonstrated back in 1974 but kept in a dormant/non-weaponized state till the late 1990s, when it became clear that Pakistan was on the brink of weaponizing its own. A second-strike capability delivered via SSBN was seriously considered at that point, and took precedence over an SSN, which would have primarily been an instrument of sea-denial.
Now with 3 Arihant-class SSBNs operational (including one of a larger sub-class unofficially referred to Arihant Stretch), the SSN program is back at the fore. But it's not the same boat as once thought.
Cabinet Committee on Security (CCS) originally granted approval for the program (then known as Project-75A) in 2015, at that point the vessel was described as a 6,000-ton design (unclear if talking about surfaced or submerged displacement, but likely surfaced). A lot has changed between then and the funding grant in 2024, possibly reflecting in the program designation changing to Project-77.
This tweet summarizes what is known about the program (as of mid-2026), I've pasted the text below just in case it's deleted later:
View: https://x.com/Parthu_Potluri/status/2067512983241244782?s=20
What is CONFIRMED by reliable sources so far:
1. It will indeed displace around 10,000 tons (one figure quoted by an older source states a very specific 9,800-ton figure). So very much in the league of Russia's Yasen, China's future Type-095 & upcoming SSN-AUKUS boats, and significantly bigger than UK's Astute, France's Suffren or the earlier blocks of US' Virginia-class boats.
2. It will be powered by a 190-200 megawatt PWR known as CLWR-B2. A shore-based prototype of which is known to have been in existence at least as of 2018. (Comment: This will be the same reactor that goes on the S-5 class SSBNs as well).
3. It will have VLS capability. Described as having "close to a dozen" VLS cells of the 'large' variety, so would be capable of launching likes of BrahMos/future Scramjet-based Hypersonics & possible ASBMs/HGVs.
4. It will be a double-hulled design, similar in that regard to Russia's design philosophies.
What has NOT BEEN CONFIRMED so far:
5. Whether it will have an X-form rudder or conventional cross-form rudder/tail planes.
6. Whether Nuclear-Electric Propulsion (NEP), aka Turbo-Electric Drive will be implemented or not.
7. Whether the boat will have a Pump-Jet Propulsor (PJP) or not. The PJP & NEP implementations might be tied to each other, and will have implications on whether we follow the Russian operational doctrine of speed over stealth or if we choose to go with Western doctrine. This is the most interesting part to look forward to as Pumpjet & NEP are much more likely to find application on the S-5 SSBN program, which is in a much more advanced stage than the SSN (first 2 boats already in construction). So we can be relatively certain that whether we put it on the SSN or not might come down to doctrinal choices.
What has not been confirmed, but is EXTREMELY LIKELY nevertheless:
8. It will make use of conformal sonars. Especially a Conformal Bow Array (CBA) along with flank arrays integrated into the hull. Provision of towed array will anyway be there.
9. It will make use of non-hull penetrating optronic & other radiofrequency masts, a technology we've already commercialized for production.
