January 31, 2018

Submarine ARA San Juan only had a Weak Hull (eg. 100 Meter Operating Depth)

From November 18, 2017 to December 1, 2018 Submarine Matters reported many aspects of the loss of the Argentine submarine ARA San Juan. San Juan remains lost without a trace, even though several countries continue to look for it.

On January 30, 2017 International Business Times reported  :

" The ARA San Juan was “’limited’ in its operational depth at 100 meters...because at greater depth [it] could not ‘guarantee its watertightness’, according to the document" [the document may be from the Comprehensive-Nuclear-Test-Ban-Treaty-Organization (CTBTO) or US Naval Intelligence (?)]

The new internal document may be able to shed light on what happened to the ARA San Juan. Officials still had not determined the cause of the submarine’s disappearance, though a report released in January by SaveTheRoyalNavy(dot)org said it was likely that all crew on board died from an explosion on the vessel.

An acoustic signal was detected the day the submarine disappeared that authorities said was consistent with the sound of an implosion of pressure inside the ship at a depth of 388 meters... The report stated the explosion was equivalent to 5,669 kilograms of TNT which would have destroyed the hull in 40 milliseconds." [this is according to a CTBTO and/or US Naval Intelligence report]

COMMENT

By setting a safe operating depth of 100 meters the Argentine naval authorities must have decided that San Juan had a severely weakened pressure hullOnly a 100 meter safe operating depth is surprisingly shallow. Even German Type XXI submarines built in 1943 had "Test" (ie. operating) depths of 240 meters (see sidebar). A weak pressure hull may be due to one or several factors including:

-  age (San Juan was completed 35 years ago in 1983). A 25 to 30 year operating life for a well
   maintained submarine is considered standard.
-  age in conjunction with too many deep immersion cycles (repeated deep diving, then surfacing
   gradually causes metal fatigue in the pressure hull over a number of years).
-  the Argentine Navy is notorious for poor maintenance
-  extensive and/or improper hull cutting for engine maintenance (cutting or welding pressure hulls
   weakens them) and/or
-  too much rust and saltwater corrosion of the pressure hull shell and of strengtheners.

In general the newer the submarine the stronger its steel alloy pressure hull and the deeper it can safely dive (see here and here). Titanium alloy permits much deeper diving (eg. Russian Alfa class submarines) but titanium is more expensive to process, weld, use in construction and repair.

Pete

10 comments:

Anonymous said...

Hi Pete

Severe adhesion of marine organisms which results in loss of ship speed is obserbed in the bow of San Juan submarine proving poor maintainance [1].

[1] http://www.abc.net.au/news/2017-11-24/undated-photo-of-san-juan-submarine/9187032

Regards

Peter Coates said...

Thanks Anonymous

The photo you provided - at http://www.abc.net.au/news/2017-11-24/undated-photo-of-san-juan-submarine/9187032 - certainly shows those organisms, called barnacles https://en.wikipedia.org/wiki/Barnacle .

Those barnacles may have made San Juan heavier. This may have made the crew's job more difficilt in maintaining depth.

Regards

Pete

Anonymous said...

Looks like the Argentines are getting desperate to find the lost sub:


Psychic hired to find missing Argentine submarine that vanished with 44 people on board:

https://www.mirror.co.uk/news/world-news/psychic-hired-find-missing-argentine-11933222

Anonymous said...

Hi Pete

Since use of organotin tributyltin (TBT), which is very effective to prevent from biofouling but provides serious environmental damage, is prohibited [1], organotin free anti-biofouling coating which is recognized by Classification Society [2] is applied for submarine.

[1] https://en.wikipedia.org/wiki/International_Convention_on_the_Control_of_Harmful_Anti-fouling_Systems_on_Ships
[2] https://en.wikipedia.org/wiki/Classification_society

Regards

Anonymous said...

Dear Pete,
in my opinion the pressure hull itself is not the main problem. I guess all the pipes running through the hull to the inside are much more a problem.

A broken pipe flooding the submarine is a plausible explanation for what has happened. Main engine is not required to surface a submarine. Just blow out the ballast tanks. That works in case the submarine is without additional seawater ballast inside the hull.

Regards,
MHalblaub

Peter Coates said...

Hi MHalblaub

With regard to "Just blow out the ballast tanks. That works in case the submarine is without additional seawater ballast inside the hull."

Information of 31st January 2018 at https://www.dailystar.co.uk/news/latest-news/678498/missing-Argentine-submarine-monitor-British-nuke-sub-near-Falklands is very signicant:

"The Argentine media also reported that, before its disappearance, the ARA San Juan only had 14 of the 100 canisters of oxygen it was supposed to carry for emergencies."

If San Juan was lacking most of the canisters to blow out water ballast it may not have been able to surface as much as usual, ie. it was unsafe.

Alternatively if some or all 14 canisters were for the crew to continue to breathe this may also have contributed to the San Juan disaster.

Regards

Pete

Anonymous said...

Dear Pete,

I think there is a difference between canisters for emergency oxygen supply and pressure cylinders for compressed air to blow out the tanks. On the other side maybe something was lost in translation.

The whole article shows the submarine was in bad shape.

Regards,
MHalblaub

Peter Coates said...

Hi MHalblaub [at 3/2/18 10:04 PM]

Yes the Argentinians were unclear. But if they definitely meant "oxygen" instead of air [to blow out water ballast tanks] then it does indeed mean emergency oxygen to keep the crew breathing longer if ARA San Juan was intact but on the seafloor.

Even if San Juan had the standard 100 oxygen tanks (enough for 48 hours) the 48 hours expired with the conclusion all died.

Regards

Pete

Shawn C said...

Dear Pete,

FYI - you not have caught this video, but back in late Nov 2017 an ex-USN bubblehead (LA Attack boats) now live-streaming gamer analysed the sonogram of the San Juan implosion. His conclusion is at 51:30 and sounds plausible though different from that of Bruce Rule.

https://youtu.be/bc39NVy1v20

Peter Coates said...

Thanks very much Shawn C [at 3/4/18 3:04 AM] on what a probable true expert says happened to ARA San Juan using sound analysis.

In line along Sub Matters' independent hunches on battery gas fire, then explosion
from http://gentleseas.blogspot.com.au/2017/11/argentinian-submarine-san-juan-likely.html
of November 18, 2017 to
http://gentleseas.blogspot.com.au/2017/11/wide-search-area-for-san-juan-may-take.html November 28, 2017

I looked at https://youtu.be/bc39NVy1v20 and, to cut a long description short, 1 hour 21 minutes 30 seconds in (1:21:30) the ex USN analyst concludes that:

a Battery gas Fire

led to a gas Explosion

followed "by a minute and 15 seconds of the crew reacting" to the explosion

crew conducted an Emergency [high pressure oxygen tanks "flasks"] Blow for 20 seconds [to try to get San Juan to the surface]

followed by the San Juan "foundering" ie. uncontrollably sinking over the next minute

where it eventually makes another sound, followed by two more sounds

each diminishing in [distant hydrophone detected "loudness"]

Thus https://youtu.be/bc39NVy1v20 is a very intricatly argued account of "the death" of San Juan.

Pete