Possible influences on India's future S5 SSBNs

A comment following Gessler's fine April 25, 2026 article is: 

As well as Kilo square sail characteristics influencing the Arihants, Russia's Delta SSBNs (with similar square sails side on) and hump back would influenced India's  Arihant designs. 

What INS Arihant (and Arighaat) may look like. Note square sail, planes on sail and hump back (Artwork courtesy H I Sutton at Covert Shores).
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I theorise that Russia has suffered so much financially from Ukraine war sanctions and higher tri-service defence spending that Russia may have traded accelerated SSBN and SSN design secrets to India. Unlike China (1969) India has no record of fighting Russia. So little risk for Russia that its defence tech exports to India would be used against Russia.

In return guaranteed Indian purchases of Russian oil and gas and joint energy projects have been considerable.

Its possible the now 30 year old Russian Borei/Borey SSBN design features will influence India's future full size S5 SSBNs. Also design features of the French and now German SSKs sold to India will influence India's S5 SSBNs.

 

Possible Borei/Borey SSBN design (Artwork courtesy Mike1979 Russia - Own work at Wikipedia (right sidebar).
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Overt and covert intelligence gathering (proud professions) about current UK, US, Chinese and French SSBN programs, would also influence India's S5 designs.

See previous Submarine Matters articles on the S5s HERE.

Trump Picks Well Qualified Ambassador to Australia

Pete Comment

Australia often has to put up with US Ambassadors who are shopping mall developers, golfing buddies and, most importantly, donors to US presidential campaigns.

Now Trump has shocked all by picking someone more than qualified.

Articles

Australian Associated Press (AAP) via the Canberra Times reports https://www.canberratimes.com.au/story/9234452/trump-reveals-long-awaited-pick-for-top-australia-post/ [link is behind a Paywall] April 28, 2026:

"Trump has announced his pick for the next American ambassador to Australia more than a year after [Trump's] return to the White House.

Former Virginia congressman David ["Dave"] Brat was nominated for the ambassador role, which has been vacant since 2024...

The ambassador position is yet to be finalised as the appointment needs to be ratified by the US Senate...

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Wikipedia https://en.wikipedia.org/wiki/Dave_Brat reveals Dave Brat is unusually well qualified, given: 

"Brat earned a B.A. in business administration from Hope College in 1986, a master's degree in divinity (M.Div.) from Princeton Theological Seminary in 1990 and a Ph.D. in economics from American University in 1995.^[11][12][13]

Academic career

After working for Arthur Andersen and as a consultant for the World Bank,^[14] Brat joined the faculty of Randolph–Macon College in 1996^[12] as an economics professor.^[15] For six years, Brat chaired the college's department of ethics and business.^[12] At Randolph-Macon, Brat taught courses including "Britain in the International Economy", "International Economic Development", and "Business Ethics".^[16]

From 2010 to 2012, Brat headed Randolph-Macon's BB&T Moral Foundations of Capitalism program. Endowed by the BB&T Corporation, the program was one of 60 similar programs devoted to the study of capitalism and morality in philosophy and economics departments at U.S. universities.^{[17][18][19][20]}

In 2006, Brat was appointed by Virginia governor Tim Kaine to the Governor's advisory board of Economists. He has also served on the board of directors of the Richmond Metropolitan Authority, and on the advisory board of the Virginia Public Access Project.^{[20][better source needed]}

In January 2019, following his defeat in the 2018 congressional election, Brat was named dean of the Liberty University School of Business.^[21] In May 2023, Brat became Vice Provost for Engagement and Public Relations at Liberty.^[22]"

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India Commissions 3rd SSBN 'INS Aridhaman'

On 4 April 2026, the Times of India reported that Defence Minister Rajnath Singh, alongside Chief of Naval Staff Admiral Dinesh K. Tripathi, had attended the commissioning ceremony of INS Aridhaman, which is the third of the Indian Navy’s Arihant-class nuclear-powered ballistic missile submarines (SSBNs).

In keeping with the tight lid on press releases regarding the SSBN program, not a single image has so far made it to the press from the event itself.

Annotated 3D model of an Arihant Stretch-class SSBN. Sourced via Reddit.
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As written on SubMatts earlier, the INS Aridhaman, also known by its hull number ‘S4’ (and presumed pennant number SSBN-82) is the first of the ‘Arihant Stretch’ sub-class, which has 8 missile launch-tubes and is estimated to be about 130 meters long as opposed to the first two boats which were about 110 meters long and only had 4 missile tubes. The displacement figures are also estimated to have gone up from about 6,000 tons surfaced (possibly ~8,000 tons submerged) to around 7,000 tons surfaced (and ~9,000 tons submerged) on the Stretch.

While the S4 boat, just like the previous two, retains the flexibility to carry either a single K-4 intermediate-range submarine-launched ballistic missile (SLBM) per launch tube or up to 3 x K-15 short-range SLBMs in a triple-packed configuration in each tube (for a total of either 8 x K-4s or up to 24 x K-15s, or any combination in between), it is my opinion that both S3 and S4 would only carry the K-4 SLBMs, due to reasons I mentioned in a previous article of mine.

The Fourth (and presumed last) boat, only known so far by its hull number ‘S4*’ (pronounced S4 Star) and widely anticipated to be named INS Arisudan, is also a ‘Stretched’ boat.

Comparison of Arihant & Arihant Stretch sub-class. Artwork by H.I. Sutton of Covert Shores.
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I had previously written about the launch ceremony of the S4* which had happened in October 2024. I had speculated then, based on reasoning mentioned within that article, that the Fourth boat could be commissioned by 2028 or thereabout, which would then mark the end of the Arihant-class build program.

It is widely believed that every Arihant/Arihant Stretch-class boat since the S3 (INS Arighaat) has an 'improved' Pressurized Water Reactor or PWR, which I had designated as the 'CLWR-B1v2' in the absence of any official literature on what the improved variant should be called. It's not known for sure as to what all went into the improved reactor and how it differs from the base variant that powered the first-of-class INS Arihant (hull S2).

1. Anzac Day songs 2. My Grandfather at Gallipoli

 Two songs by Eric Bogle, in Remembrance:

Greenfields of France (also called No Man's Land and Willie McBride)

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The Band Played Waltzing Matilda (above) also by Eric Bogle, which is more to do with Gallipoli and the repatriation of a crippled Digger.

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My Grandfather, Staff Sergeant Leo Coates (above standing) in 1915. He worked at the 1st Australian "Stationary" Hospital (but still a field hospital). This was situated at Mudros, on the Mediterranean island of Lemnos, near Gallipoli. Here Leo's doing an X-ray - looking for a bullet in a wounded Anzac's leg. (The photo was donated by the Royal Australasian College of Surgeons - Photo courtesy oof the Australian War Memorial Archive).

Leo then shifted to Gallipoli later in 1915, where the field hospital was shelled by the Turks - because the Turks knew the Aussies were hiding ammunition in some of the hospital tents!  

Leo Coates was involved in early mobile X-ray machine development. Then, after he returned to Australia, he helped develop and operate permanent veterans' hospital X-ray machines. 

Australia orders three Upgraded Mogami frigates from Japan

Following the Japanese Ministry of Defense award of a contract to Mitsubishi Heavy Industries (MHI) to build three upgraded Mogami-class (06FFM) under the Japanese FY2025 defense budget (see page 31), Australia immediately signed the “Mogami Memorandum” - the expected deal with the Japanese government for the first batch of three Upgraded Mogami-class frigates, the first of which is scheduled for delivery in December 2029.

Upgraded Mogami Model displayed by MHI at Indo Pacific 2025. Image: navalnews.
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The following chart, provided by Navalnews.com to highlight the rise in cost for the upgraded Mogami, also indicates that FY2025 is the first year three hulls have been ordered. As an upgraded Mogami takes three years from hull laying to launch, this should indicate that the ‘third’ FY2025 hull is the first Australian ship to meet Australia's tight delivery timeline.

We have discussed the 06FFM when the class was selected by the Royal Australian Navy (RAN) to fulfil its General Purpose frigate program (project SEA 3000) in August 2025, but it is surprising how fast Australia is moving forward with this AUD$20-25 billion dollar program, with the remaining 8 hulls will be built at the Austal Henderson Australia facility, now a very busy shipyard as Austal is ramping up for construction of eighteen Landing Craft Medium (LCM) and eight Damen LST1000 Landing Craft Heavy (LCH). All 18 LCMs are scheduled for delivery by 2032, while all LCH are to be delivered by 2038.

Austal will start the build programs for 8 landing craft heavy (LCH) (artwork above) and 18 landing craft medium (LCM) in 2026. Image: Austal
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The urgency and speed at which the SEA 3000 project has moved is due to the Surface Fleet Review that the Australian government commissioned in 2023, where the failure of the Arafura OPV program (mainly due to changing specifications) and the delays and cost growth in the Hunter-class saw the Australian government slash both programs in early 2024. With the RAN’s workhorse Anzac-class frigates now approaching 30 years of age and due for retirement, a near Military off-the-shelf (MOTS) solution was sought - the first batch of Australian 06FFM frigates should be delivered with few changes - it was confirmed in November 2025 that they will be equipped with SeaRAM and NSM, and will likely use the RAN's standard CEAFAR AESA radar system.

Setting up the Henderson Precinct as a major military shipbuilding hub has major domestic political bonuses for the ruling Australian Labour Party (ALP), but with Japan relaxing military export rules, Australia has now positioned itself as a big military-industrial partner to Japan.

India's oil/gas import situation improving: eg. from Russia & Iran

As a followup to Gessler’s - comments of March 17, 2026 – my friend Gessler offline, on April 16, 2026, further explained the oil/gas situation in India:

"The situation in India is fine at the moment, in fact it has gotten better in some areas.

Earlier, the government had restricted commercial users (factories and such) to a liquid petroleum gas (LPG)/liquid natural gas (LNG) quota of only 20% of their average gas requirement, so as to ensure that household users (for cooking mostly) get the maximum supply possible.

But now it seems India has succeeded in tapping alternative sources of gas (US, Russia, others), and as a result the quota for commercial users was first increased to 40%, and recently up to 70% of their average requirement. This has happened without the supply to households being effected so it appears the supply situation has gotten somewhat better on the gas front. They're also encouraging more and more people to switch to a piped natural gas (PNG) connection as LNG is not as supply-limited as LPG due to sizeable domestic deposits of natural gas.

Regarding oil and its derivatives (petrol, diesel), the situation was never as much of a concern as gas. This is because many alternative sources exist and the large refinery industry in India holds ample stocks itself. This is without even having to tap into the Strategic Petroleum Reserves, which many countries have already released into the market. But India hasn't felt the need to, yet. The prices of regular petrol/diesel (barring some specialized, high-octane versions [like 97 to 99 RON -see reference to India ] used in expensive sports cars and the like) have remained at pre-war levels. Although I suspect they might have to consider some increases if the situation persists.

While the availability of Aviation Turbine Fuel (ATF), aka jet fuel, remains assured (again, thanks to the local refinery industry), the prices of it have increased. So flight tickets have gotten costlier. The government has also increased the export tariffs on ATF so as to ensure most of what is produced here remains here.

I hope the conflict is resolved and the situation goes back to normal as soon as possible, but things look like they could go either way."

Pete Comment - Russia and Iran

One reason India's situation has gotten better in some area is because on March 13, 2026, to help deal with the economic costs of the Iran war, the US temporarily lifted restrictions on the sale of Russian oil exports - with India a major customer. 

India’s top oil suppliers in 2024. by country, were https://en.wikipedia.org/wiki/Oil_and_gas_industry_in_India#Oil_imports_by_source_country  US$51.3 Billion from Russia, $28.6 Billion from Iraq, $19.3 Billion from Saudi Arabia, $13.7 Billion from the UAE, and $5 Billion from the US.

India has long been a significant importer of Iranian oil and gas. 

As of April 2026, India has resumed importing Iranian oil for the first time since May 2019, following a seven-year hiatus caused by US sanctions. Driven by supply disruptions in the Strait of Hormuz due to regional conflict, India - the world's third-largest oil importer - is utilizing a temporary US sanctions waiver to secure energy, with tankers carrying Iranian crude to Indian ports. 

China is the largest crude oil importer, US second, then India.