Arihant Class SSBN: News & Discussion

[uddu]

^^^ Yes, this is S4. But two names are floating around - Arisudan and Arijit. Let's see which one gets assigned or perhaps a whole other name!

Arisudan (or Arisudana) is a Sanskrit name meaning "killer of enemies," "destroyer of demons" or "protector."

Arijit is a popular Indian male name of Sanskrit origin, meaning "one who has conquered his enemies" or a "victorious conqueror."

Yes Sir. The names are apt and powerful. I was just pointing out the error in the tweet that wrongly mentioned S4* as S4. People think its S1, S2, S3, S4 while the S1 is land based and the remaining S2, S3, S4 and S4* being the numbers. Yes as you know S4 and S4* being the elongated Arihant.

Wrong thread but mentioning one more news that came out, is the name given to ATAGS is Amogh. Google search for baby names Amogh suggest these
"The epitome of perfection– One who is blessed by divine grace."
The rare and special masculine given name Amogh is of Indian origin and finds its roots in the Telugu language. The name, when translated into Sanskrit, means ‘invincible’ and ‘unerring.’ Amogh is also associated with Lord Ganesha, revered as the Lord of all Wealth and Wisdom.

[SSridhar]

Indian Navy likely to commission third indigenous N-powered submarine by April-May - ToI

India’s sea-based nuclear deterrent will be strengthened soon as the country’s third indigenous Arihant-class nuclear-powered ballistic missile submarine (SSBN), INS Aridhaman (designated S4), is likely to be commissioned by April-May. “The commissioning of INS Aridhaman is expected by this summer as the submarine is currently in the final stages of sea trial,” a defence source told TOI.

Last Dec, Navy chief Admiral D K Tripathi had said that INS Aridhaman would be commissioned this year.INS Aridhaman, built under the Advanced Technology Vessel (ATV) project at the Ship Building Centre in Visakhapatnam, will be larger (7,000 tonne) than predecessors INS Arihant and INS Arighaat (6,000 tonne), featuring enhanced capability to carry long-range K-4 missiles.

INS Aridhaman will be armed with 24 K-15 Sagarika SLBMs (750 km range) and eight K-4 SLBMs (3,500 km range), which are capable of reaching most parts of Asia.

Once it enters service, India will have three operational ballistic missile submarines under the Strategic Forces Command (SFC) at sea for the first time, moving the country closer to achieving ‘Continuous At-Sea Deterrence’, a strategic defence policy where a nation maintains at least one SSBN on patrol 365 days a year.

As a stealthy underwater platform, INS Aridhaman boosts India’s “second-strike” capability—the ability to retaliate after a nuclear attack. It is designed to carry more long-range nuclear-tipped missiles than its predecessors INS Arihant and INS Arighaat.

In addition to INS Aridhaman, the Indian Navy is securing an Akula-class SSN nuclear-powered attack submarine from Russia, commonly referred to as “Chakra III”, with expected delivery by 2027 or early 2028. Besides these submarine projects, India and Germany are in the final stages of negotiating a $8-10 billion Project-75(I) deal to build six advanced, conventional diesel-electric submarines equipped with Air-Independent Propulsion (AIP) technology.

The new submarine acquisitions are timely as Pakistan is acquiring eight advanced Hangor-class diesel-electric attack submarines from China under a $5 billion 2015 deal to bolster its naval capabilities.

INS Aridhaman is equipped with an 83 MW pressurised water reactor and advanced sonar suites, possesses indigenous USHUS and Panchendriya sonar systems for better target detection and has improved acoustic damping with anechoic tiles to reduce noise, making it harder to detect. Once operational, it will be based at Project Varsha, a high-security facility with underground pens near Visakhapatnam.

[S_Madhukar]

What’s the point of loading K15 when K4 is available… I thought the option was there as they are proportionate in size as 2:1 …so K4 or 2X as many K15?

[Cybaru]

What’s the point of loading K15 when K4 is available… I thought the option was there as they are proportionate in size as 2:1 …so K4 or 2X as many K15?

sound less threatening in press to everyone. Load outs are always dependent on mission.

[uddu]

What’s the point of loading K15 when K4 is available… I thought the option was there as they are proportionate in size as 2:1 …so K4 or 2X as many K15?

These are assumption by the press. What used to be on Arihant, they are calculating and mentioning the same to tell us how many K15's it can have. Not that IN will be using the K15'S.

[Prem Kumar]

Aridhaman has 8 VLS tubes. So, it should be 24 K-15s or 8 K-4s (not *and*)

[vera_k]

Or 6 and 6. Understandable typo I think.

[bala]

INS Arihant: How India Built the Impossible

Only five nations have ever built a nuclear-powered ballistic missile submarine. In 2009, India became the sixth. This is the complete engineering breakdown of INS Arihant — from a miniaturized nuclear reactor to underwater missile launches to the crisis that nearly destroyed it all.

Key specs covered:
• 83MW compact pressurized water reactor (CLWR-B1)
• K-15 SLBM (750km range) & K-4 SLBM (3,500km range)
• Panchendriya 5-mode sonar system
• 600-tonne titanium acoustic isolation shell
• Anechoic tile stealth coating
• 2017 flooding incident & recovery

0:00 — The Impossible Machine
0:32 — The Heart: Nuclear Reactor
1:18 — The Weapons: Missile Launch System
2:02 — The Ghost: Stealth & Silence
2:45 — The Crisis: Near Destruction
3:18 — The Fleet: Deterrent Patrol

[uddu]

INS Arihant: How India Built the Impossible
• 2017 flooding incident & recovery
2:45 — The Crisis: Near Destruction

This is a fake news peddled by Pakistani channels at that time to express their jealousy. Usually in any test at berth, it's not done like some war diving scenario. There are total monitoring from Inside and outside and the process is very slow and controlled diving at the dock. If a hatch is opened, it will be visible to so many eyes at the dock standing outside. Such a submerge test at a dock must take 10's of minutes if not an hour plus rather than emergency dive in an ocean. The story is as fake as it sounds.

A video to demonstrate how it will look at the berth and how the slow process is even to submerge or to surface by pumping in/out the water. And the number of people watching such an event. Video could be A.I. but this is how it works.

Witness the mighty submarine docking!



Here you could see the timelapse, the submerging also takes almost similar amount of time as floating them.

Nuclear Submarine Dry Docks Inside Floating Dry Dock - Time-lapse Video



For better animations try these even though these are of SSN videos of US subs and Typhoon SSBN

Submarine Nuclear Power | Engineering behind it Nuclear Reactor How it Works



US Navy & Submarine Destroyed Iran's Fleet | Explained



How does a Submarine work? / Typhoon-class submarine // The worlds largest submarine ever built.

[uddu]

Third Arihant class sub to be commissioned soon. The last of the class INS Arisudan to be inducted in 2027. Undergoing sea trials from 2025.

India's Sea-Based Nuclear Deterrent That Can Reach China From The Indian Ocean | Watch

India's nuclear submarine programme has crossed from ambition to operational reality. Two Arihant-class SSBNs are currently on active deep-sea deterrence patrols. A third, INS Aridhaman, featuring eight missile tubes, double the firepower of its predecessors, and compatibility with the future K-5 missile, is set for induction in 2026. A fourth, INS Arisudan, is in sea trials. India is on the verge of becoming one of very few nations with four nuclear ballistic missile submarines active simultaneously. The K-4 missile test-fired from INS Arighaat in November 2024 confirmed India can hold targets on China's eastern seaboard from submerged positions in the Indian Ocean. India's nuclear triad is no longer theoretical. It is at sea.

[uddu]

Mostly will be with 8 K-4 rather than K-15.

https://x.com/Varun55484761/status/2039931907971121251
@Varun55484761
Nuclear submarine INS Aridhaman Commissioned

[Rakesh]

https://x.com/rajnathsingh/status/20399 ... 94676?s=20 ---->

शब्द नहीं शक्ति है, ‘अरिदमन’!

Words are not power, ‘Aridman’!

[Rakesh]

^^^
https://x.com/SandeepUnnithan/status/20 ... 51727?s=20 --->

शब्द नही शक्ति हैं। अरिदमन।

The closest we will get to a GoI announcement. Defence Minister @rajnathsingh confirms the commissioning of the INS Aridhaman (S4) in Vizag. Third of the Arihant Class SSBNs. Armed with 8 K4 SLBMs, each with a nuclear warhead. 3,500 km range missile. India’s single most powerful defence platform. Over 80% indigenous component.

[Rakesh]

https://x.com/IamRajat_Pandit/status/20 ... 48646?s=20 ---> India commissions its third SSBN - INS Aridhaman - a nuclear powered, ballistic missile 7,000 tonne submarine. A story I did in December about its commissioning.

[Rakesh]

Bigger, Better, India’s 3rd ‘Boomer’ INS Aridhaman Enters Service
https://www.livefistdefence.com/bigger- ... s-service/
03 April 2026

[uddu]

https://x.com/rajnathsingh/status/20399 ... 94676?s=20 ---->

शब्द नहीं शक्ति है, ‘अरिदमन’!

Words are not power, ‘Aridman’!

Google translated it to
It is not a word, but a power, 'Aridaman'!

[Rakesh]

India commissions its third nuclear-powered ballistic missile submarine—INS Aridhaman
https://theprint.in/defence/india-commi ... n/2895692/
03 April 2026

[Rakesh]

VIDEO: https://x.com/ShivAroor/status/2039967499337486587?s=20 ---> With third Indian nuclear ballistic missile submarine INS Aridhaman entering service today, India’s Strategic Forces Command finally has numbers to keep at least 1 of these ‘boomers’ on deterrent patrol at all times. MAJOR boost to India’s nuclear deterrent.

VIDEO: https://x.com/sougat18/status/2039928790261080332?s=20 ---> Solid Explainer on INS Aridhaman by @SandeepUnnithan. Please do listen in.

[Rakesh]

https://x.com/RicchaDwivedi/status/2040 ... 84219?s=20 --->

2016: Arihant
2024: Arighaat
2026: Aridhaman
2027: Arisudan (expected)

The biggest takeaway is pace. What was once a single milestone is now a pipeline. Marks a major doctrinal upgrade that deepens India’s credible second-strike deterrent at sea.

https://x.com/RicchaDwivedi/status/2040 ... 87361?s=20 --->

‘Ari’ = enemy, in Sanskrit.
Arihant = Destroyer of the enemy

Arighaat, Aridhaman, and Arisudan all carry variations of the same meaning: vanquishing the enemy. MoD had ‘chosen and approved this at all levels because of its subtlety and appropriateness in conveying the resolve.’

[Rakesh]

https://x.com/CaptDKS/status/2039933482072441127?s=20 ---> 'शब्द नहीं शक्ति है, ‘अरिदमन’!' - @rajnathsingh. Your guess is as good as mine. "The Ghost at the Banquet'. Third SSBN is up & running. Well Done @indiannavy and more power to you all in providing the Gold Standard in Stability & Deterrence.

https://x.com/Aryan_warlord/status/2039 ... 09347?s=20 ---> Quiet words that hide a major strategic shift. With INS Aridaman, the third Indian Navy SSBN now officially commissioned. India can now maintain a constant SSBN deterrent at Sea with one boat at sea, one prepared to leave at quick notice & one in maintenance. Also worth noting that with Aridaman the number of "nukes" the Indian Navy can field at sea has essentially doubled, as this submarine has eight launch tubes compared to four on INS Arihant or INS Arighaat. That in itself is another strategic leap.

[Rakesh]

INS Aridaman: India’s Nuclear Shield Gets Stronger

India’s third nuclear submarine is now in play but what does that really change? With INS Aridaman, India may have quietly stepped into continuous at-sea deterrence, the ultimate nuclear insurance. How do these invisible submarines prevent war? Why are they called the most survivable weapons ever built? And what comes next—bigger subs, faster attack boats or underwater drone swarms?

[S_Madhukar]

https://x.com/RicchaDwivedi/status/2040 ... 84219?s=20 --->

2016: Arihant
2024: Arighaat
2026: Aridhaman
2027: Arisudan (expected)

The biggest takeaway is pace. What was once a single milestone is now a pipeline. Marks a major doctrinal upgrade that deepens India’s credible second-strike deterrent at sea.

https://x.com/RicchaDwivedi/status/2040 ... 87361?s=20 --->

‘Ari’ = enemy, in Sanskrit.
Arihant = Destroyer of the enemy

Arighaat, Aridhaman, and Arisudan all carry variations of the same meaning: vanquishing the enemy. MoD had ‘chosen and approved this at all levels because of its subtlety and appropriateness in conveying the resolve.’

These are nice saatvik names from Buddha ka Desh .. hope next ones are more tamsic names like Vidhwans, Prahar, Pralay, Vinash, Sanhaar etc

[Rakesh]

The Silent Fleet: How India Built Nuclear Submarines in Secret

In 2026, a nuclear submarine slipped beneath the Indian Ocean and disappeared. No announcement. No fanfare. Just silence — exactly as intended. This is the story of how India built the world's most secretive weapons program from scratch. It begins with humiliation: a single American aircraft carrier sailing into Indian waters to end a war. It ends with three nuclear submarines capable of surviving a first strike and retaliating from the deep. The story in between spans 56 years, $14 billion, three catastrophic failures, a secret Soviet deal, borrowed technology, and a nuclear reactor that took 27 years to build. India is now one of only six countries to complete the nuclear triad — the ability to launch atomic weapons from land, air, and sea. The submarines are the hardest piece. The most survivable. The most credible deterrent. The ones that ensure no adversary can ever believe they can win a nuclear exchange against India. This is that story.

[uddu]

First step to Nuclear Triad happened. It need made formidable with the S5's in good numbers.

[Prem Kumar]

Another leg of the triad which has strengthened its importance, is the stealth bomber. Once in the air, its impervious to interception

Its vulnerable only when its on the ground. So, if we invest in an "always X aircraft in the air" doctrine (which the US and USSR did), its a highly survivable second-strike leg

Even in a purely conventional role, these are potent kick-the-door-open SEAD platforms

Doctrinally, we seem to be blind to the importance of a stealth bomber fleet. Largely in part due to the jock-mentality of the IAF top-brass

[Manish_P]

Another leg of the triad which has strengthened its importance, is the stealth bomber. Once in the air, its impervious to interception

Its vulnerable only when its on the ground. ...

Prem Ji, I think the difficulty with regards to the Low RCS bomber is that it can be detected only at a very short range by powerful radars (both ground based and AWACS)

Hence it is used by the US only against countries which don't have powerful radars (or have them jammed/destroyed), preferably in dry weather and preferably at night.

The US also sends ELINT aircrafts before the actual air campaign so that they can map out where the enemy Radars coverage area / gaps are, the time on/off etc (Radars have down time for maintenance, especially in countries without good power supply, cooling systems etc)

But i do concur with your overall point of having a good number of low RCS bombers. Maybe we could get it developed faster than a 5th/6th gen Fighter since the speed/manouverability/altitude requirements will not be as demanding....

[uddu]

India Evaluates Building S4-Class Derivatives as SSGNs to Provide Long-Range Strike Capability Ahead of Project-77 SSNs
https://defence.in/threads/india-evalua ... sns.17399/
08 April 2026

Plans to build 4 SSGN based on the S4 design of Arihant. Minimum 5 to 7 Brahmos or ITCM missiles can be stored in each such launcher tube meant for K4 missiles. One such sub could carry about 40 to 56 missiles. So 4 such SSGN's and 3 available will give us 120 to 168 cruise missiles from underwater.

[Rakesh]

INS Aridhaman Unleashed | Big Boost To India’s Nuclear Triad

India has commissioned its third indigenously built nuclear-powered ballistic missile submarine, INS Aridhaman. The submarine is larger and more lethal than its predecessors, INS Arihant and INS Arighat. It features eight vertical launch tubes capable of carrying long-range K-4 or K-15 missiles, significantly boosting the sea-based nuclear deterrence and second-strike capability of the country.

[Rakesh]

India inducts third indigenous nuclear sub, joins elite group
https://www.tribuneindia.com/news/top-h ... ite-group/
04 April 2026

[Rakesh]

https://x.com/Defencecore/status/204046 ... 62285?s=20 ---> Overview of Indian SSBN Program with its Indigenisation & Capability Growth.

> INS Arihant with its 55% indigenisation, covered hull, reactor integration & core systems, with some foreign inputs.
> INS Arighat raised this to 70-75% with a refined 83 MW PWR, quieter propulsion & more indigenous combat systems.
> INS Aridhaman has reportedly pushed indigenisation beyond 80% with reactor efficiency, sonar, FCS & acoustic stealth.
> INS Arijit (S4*) which is under trials & will join service by 2027 will have minor enhancements. Primarily it had ensured dockyard continuity between the S4 and the S5.
> The S5 Class will mark a major jump in capability growth with its larger size (13,500 tons) more powerful 190 MW BARC reactor, LR-SLBMs like K5, K6 & next-gen stealth capabilities.

[Rakesh]

https://x.com/lakshmishaks/status/20402 ... 33054?s=20 ---> India inducts INS Aridaman, 3rd SSBN, with higher missile capacity than INS Arighaat (2024). Commissioning adds to nuclear triad alongside INS Arihant (2016). Induction includes INS Taragiri frigate, expanding naval fleet capabilities.

[Rakesh]

https://x.com/Parthu_Potluri/status/204 ... 63089?s=20 ---> The third SSBN, INS Aridhaman, is commissioned!

As reported earlier, the S4 marks the advent of the "Arihant-Stretch" sub-class. The biggest outwardly visible change being the expansion of missile launch cells from 4 to 8, translating into an ability to carry either 8 x K4 intermediate-range SLBMs for a 3,500-km nuclear strike range or up to 24 x K15 short/medium-range SLBMs for a 750 to 1,900-km nuclear strike range. Though some say that the improved/uprated nuclear reactor (believed to output about ~100MWth as opposed to the ~83MWth of the first boat) has only come online with the S4, my opinion on this differs. I suspect that the improved reactor has in fact been operationalized on the second boat (INS Arighaat, hull S3, pennant SSBN-81) itself.

This opinion is supported by the fact that the 2nd boat in class (Arighaat) was commissioned about 8 years after the first, whereas the 3rd boat is being commissioned just ~1.5 years after the 2nd. The significantly longer time S3 took to be accepted into operational duties aligns with the possibility that they had to certify a new, uprated reactor configuration (alongside fixing any design/engineering niggles discovered during the 1st boat's operation at sea). With the additional missile compartment 'plug', along with other possible improvements, the technology-insertion program continues with the Arihant-class, each boat is more capable than the last in multiple ways!

I'd love it if the last boat in class (hull S4*) turns out with a pump-jet propulsor! Provided the technology is ready (I don't know if it is), it would make sense to de-risk some aspects of the future S5 SSBN & P77 SSN programs by proving the pump-jet on the S4*.

[S_Madhukar]

So curious if a boomer just stays on the sea bed with minimal systems on , is it stealthy enough ? If not I hope S5 and beyond keep on improving noise and stealth tech. The Chinese mapping ship is again on its way to the Indian Ocean , if it maps the bed and does signal intelligence, can they track our boomer ?

[Manish_P]

Theoretically correct that the minimum systems that are switched on and the less movement your sub does, the lower the chance of acoustical, electromagnetic, wake and thermal detection.

But given that the maximum operating depth for submarines is a few hundred metres you would need to come close to the enemy coastline to be able to be just above the sea bed (no sub likes to actually sit on the sea bed) in order to try and hide in the sonar returns clutter.

Closer distance will give the enemy lesser time to react to your missiles but it could also make it more difficult for you to get away from their counter attack.

Warmer, shallower seas with gentler gradient & good thermoclines like our coastline would be easier for subs to hide than cold oceans up north.

[uddu]

INS Aridaman: India’s Nuclear Deterrence At Sea Gets A Boost
With a cryptic tweet from Defence Minister Rajnath Singh and a silent induction, INS Aridaman joined the Indian Navy's fleet in early April 2026. The induction raised India's nuclear-powered ballistic missile submarine (SSBN) strength to three.

Joining the ranks of INS Arihant and INS Arighat, Aridaman will vastly bolster India's nuclear triad, helping establish a reliable continuous at-sea deterrence (CASD) that allows sustained deployment cycles at sea, Rear Admiral Sudarshan Shrikhande (Retd) told Editor-in-Chief Nitin A. Gokhale.

SSBNs form a major component of India's second strike capability. Aridaman's induction is an important step that elevates India's nuclear deterrence architecture to a whole new level, he added.

Compared to INS Arihant and INS Arighat, the 7,000-tonne Aridaman can carry more K-15 missiles, as well as the intermediate-range K-4 nuclear-capable submarine-launched ballistic missiles (SLBMs).

With this induction, India joins a select group of nations, including the United States, Russia, the United Kingdom and China that operate a full-fledged nuclear triad backed by nuclear-powered submarines.

[drnayar]

So curious if a boomer just stays on the sea bed with minimal systems on , is it stealthy enough ? If not I hope S5 and beyond keep on improving noise and stealth tech. The Chinese mapping ship is again on its way to the Indian Ocean , if it maps the bed and does signal intelligence, can they track our boomer ?

Most nuclear-powered submarines are generally not designed to rest on the ocean floor. Their cooling water intakes are located low on the hull, and resting in sand or silt can clog these vents, causing the reactor to overheat.Only a few "special mission" submarines, like the USS Jimmy Carter or the historical NR-1, have retractable skids or "legs" specifically designed to hold the hull above the seabed to avoid these issues.: Instead of bottoming SSBNs use advanced "hovering systems" to stay stationary at specific depths without making noise from propulsion.

Even if a submarine remains stationary on the seabed, it is still vulnerable to modern detection methods., Nuclear reactors must constantly pump coolant, creating a faint but persistent acoustic signature.Sophisticated software can now process active "pings" to see the exact physical profile of a submarine sitting on the seabed.Aircraft can detect the massive metal hull of a submarine even if it is completely silent.Plus., the heat emitted from the hull remains detectable by infrared sensors on satellites and helicopters

Role of mapping or survey ships : By mapping seabed ridges, water temperature, and salinity, China can predict how sound travels in specific zones. This allows them to identify "acoustic shadow zones" where a submarine might hide or optimize their own sonar to "see" through natural clutter.Having a high-resolution map of the ocean floor allows them to detect any "new" large metal object that wasn't there before, making it much harder for a boomer to blend into the terrain.These ships can analyse local radio frequencies and underwater signals to identify the unique "acoustic fingerprints" of foreign submarines, allowing for easier tracking in the future.

The next generation of ballistic missile submarines, including the U.S. Columbia-class and India’s S5-class, is being engineered to be the quietest in history. These vessels move beyond the mechanical limits of current fleets by replacing traditional gears and propellers with fully integrated electric and fluid-based systems.

enough said