Disappeared Argentine Submarine

[Enthalpy]

Hello everyone!

The Argentine submarine ARA San Juan last reported on November 15.

On November 23, the Navy published that two hydrophone stations operated by the CTCBO, meant to detect nuclear explosions, heard a non-nuclear explosion near the possible position of the submarine, suggesting a total loss of the ship. My information isn't at the source, alas - data from Twitter, and so on.

Signals, positions of the hydrophones, timescales
https://twitter.com/SinaZerbo/status/933745155399708674/photo/1
do you understand too that the three blue-to-red histograms are strongly amplified, hence the scale does not apply? I suppose the blue histogram maybe fits the scale in dB ref µPa²/Hz, the others not.

How do you understand the several replicas after 90s? I can only image an artefact from signal processing. An echo would need a reflector >70km away, and then the echo couldn't have an amplitude similar to the first sound.

Do you know if the hydrophones on Tristan da Cunha were active? And if yes, why didn't they pick the noise? They were nearer than the ones at Ascension and Crozet that picked it
https://www.ctbto.org/verification-regime/featured-stations/types/hydroacoustic/ha09-tristan-da-cunhaunited-kingdom/
https://www.ctbto.org/verification-regime/featured-stations/types/hydroacoustic/ha09-tristan-da-cunhaunited-kingdom/page-1-ha09/
https://pbs.twimg.com/media/DPVIXa_W4AEyAcF.jpg
and from the sensitivity map (look at the shadows by the islands), those on Tristan da Cunha seem as efficient as the others, to the West too
https://twitter.com/ferencdv/status/933737271748050944
they were put into service before 2010.

And if the hydrophones' sensitivity at the inferred loss location wasn't worse than 1t TNT or 4.2GJ (see map), it corresponds to 7MPa (700m depth to crush the hull) times 600m³, or 1/6^th the vessel's volume (D=8.2m L=65m), so at least this would be consistent. It's consistent with other potential sources too.

Thank you!

Edited November 24, 2017 by Enthalpy

[swansont]

Multiple events could be different parts of the hull collapsing (in an emergency, the water-tight doors would have been closed), or an explosion and then hull collapse. I think that something similar was reported when the USS Scorpion was lost in '68.

[Moontanman]

Very sad event, being a submariner has to take cojones...

[Endy0816]

15 hours ago, Moontanman said:

Very sad event, being a submariner has to take cojones...

They're normally safe from most threats. When things do go wrong you can easily lose the whole crew though.

 

Probably was like Swansont said, another event coming right after. There's seperate compartments, tanks and several peices of equipment that don't care for seawater.

I was thinking seawater density variations, sea floor and sea mounts might be a possibility as well.

Edited November 25, 2017 by Endy0816

[swansont]

43 minutes ago, Endy0816 said:

They're normally safe from most threats. When things do go wrong you can easily lose the whole crew though.

That's the issue on subs, and on ships to a somewhat lesser extent. It's one reason why they have redundant safety measures, and why they run lots of drills.

It also takes a certain mental strength to be locked up in a tin can for months at a time — even more so for the nuke subs, who do not surface to recharge batteries and ventilate.

43 minutes ago, Endy0816 said:

Probably was like Swansont said, another event coming right after. There's seperate compartments, tanks and several peices of equipment that don't care for seawater.

I was thinking seawater density variations, sea floor and sea mounts might be a possibility as well.

It's interesting that the report is of an explosion, rather than implosion. I don't know if that's sloppy reporting or if there is a distinction in the acoustic signature.

[Endy0816]

17 hours ago, swansont said:

That's the issue on subs, and on ships to a somewhat lesser extent. It's one reason why they have redundant safety measures, and why they run lots of drills.

It also takes a certain mental strength to be locked up in a tin can for months at a time — even more so for the nuke subs, who do not surface to recharge batteries and ventilate.

It's interesting that the report is of an explosion, rather than implosion. I don't know if that's sloppy reporting or if there is a distinction in the acoustic signature.

I wish I felt drills were effective, but many of the major incidents are a result of one-off events.

Honestly, underway is very relaxed. Lot of downtime. Did miss seeing the Sun and being able to readily communicate.

 

Not sure on sound profiles. Feel bad for the sailors either way. Hopefully investigation can give families closure.

[swansont]

6 hours ago, Endy0816 said:

I wish I felt drills were effective, but many of the major incidents are a result of one-off events.

That the "routine" emergencies are not the cause could mean that drills are indeed effective. You know how to react, so if the magnitude of the problem is small enough, there is minimal impact.

[Enthalpy]

I read that there are no compartments with pressure-proof separations in the too small TR-1700 type of submarine. The source wasn't reliable and I don't find it again. At least, these drawings show no internal wall capable of resisting 70bar to make successive bangs:
http://www.diariojornada.com.ar/200791/paismundo/confirman_que_el_ara_san_juan_sufrio_un_cortocircuito_antes_de_perder_contacto/
http://www.elsnorkel.com/2011/09/el-casco-del-s-42-ara-san-juan.html
Only the front of the pressure hull, at the rear of the torpedo tubes, is round. Successive collapses would have been the most likely explanation for me too.

Implosion versus explosion: at small distance it can be told, but at 6,000km I don't think so, because the distortions are too big. If the blue histogram is unprocessed, then the sound peaks at 10Hz with only 2.5Hz bandwidth, so it has several periods, and telling an overpressure from an underpressure is impossible. Looks like Cbcto told "explosion" and later it was deformed, including in wrong senses.

The (processed) signal from Ascension shows at least three peaks at the event and none right before nor after. They are too many for one own torpedo explosion followed by one hull collapse. I don't imagine neither the hull  nor the other own torpedoes resisting the explosion of one own torpedo - but I could be quite wrong since these warheads are designed for underwater effects and they would have been in air.

Successive heard bangs being echoes on different water layers: 90s delay need 135km distance difference so they can't result from reflections at 3km seabed depth. Propagation through different layers? This would need several times 2% celerity difference. That's about the difference between -800m (1479m/s minimum) and -3000m (1506m/s in mean Ocean water). How would the sound stay in a faster medium? I don't know Ocean acoustics well enough.

Multiple paths through different longitudes are hard to imagine. 135km more than 6000km need the sound to go 627km to the East or West on the first 3000km, then turn somehow to reach the listening station with almost the same strength. On the Cbcto's sensitivity map, shadows by islands are clearer than that, over long distances.

Did you see the signal received at Crozet? Have a link maybe?

Did you read if Tristan da Cunha received a signal? They should have, but I've read only about Ascension and Crozet.

Edited November 26, 2017 by Enthalpy

[Enthalpy]

Enrique Balbi, spokesperson of the Argentine Navy, excluded today that the own weapons could destroy the ARA San Juan, because the submarine didn't carry combat torpedoes:
http://www.laprensa.com.ar/459901-La-Armada-dijo-que-sigue-sin-ser-detectado-el-ARA-San-Juan-y-suman-medios-a-la-busqueda.note.aspx
Además, descartó que esa explosión o implosión pueda haber sido causada por armamento propio, ya que el San Juan "no tenía torpedos de combate".

Single pressure-resisting volume too, if I read the drawings properly.

This makes more desirable an explanation of the multiple bangs heard at Ascension. And more wanted, the records at Tristan da Cunha (if any) and at Crozet.

It would help quench alternative explanation attempts, which include even an attack:
Consultado sobre versiones que circulan en redes sociales, el portavoz naval subrayó que "ningún indicio" indica que "haya habido un ataque exterior al submarino ARA San Juan".

[DrP]

On ‎24‎/‎11‎/‎2017 at 6:38 PM, Moontanman said:

Very sad event, being a submariner has to take cojones...

I believe it does. My Uncle was in a submarine for the whole of WW2 - he had some amazing stories. Being honest it sounded pretty hellish.

[Enthalpy]

The CTCBO has published a better estimate of the location of the explosion. Still nothing about a detection by their station on Tristan da Cunha, but they used the signals recorded by their seismic stations in Argentina and on the Falklands instead of the hydro-acoustic stations. In part because these stations are nearer to the source, the combed area is now much smaller.
https://twitter.com/sinazerbo?lang=en
https://www.clarin.com/sociedad/submarino-ara-san-juan-nuevos-datos-lugar-explosion-reducen-radio-busqueda_0_ryz0ouieG.html

By the way, what I had called "hydrophones" are on the ground and they pick the ground movements created by Oceanic acoustic waves. The CTCBO distinguishes them from seismic stations, I don't understand the difference. Maybe a matter of frequency and of position nearer to the Ocean.

In order to improve the accuracy of the seismic method and double-check it, it might be possible to create sound at a few locations near  to the target and identify finely how it propagates to both ground stations. It doesn't need to be an explosion; anything with a broad band fits, and duration can compensate intensity. The propagation time will be known more accurately, the frequency response compared with the spectrum of the picked explosion sound would give additional information, and maybe echoes (if the received frequencies aren't too low) would tell more about the distance to the surface and the sea's bottom, the distance to the continental shelve. A helicopter-borne sonar can be there rather quickly: I don't know how flexibly they can choose an emitted signal. When used to communicate with submarines, they can emit for longer than a ping.

Some active sonars are already in the search area, so if they can emit also in the frequency band picked by the seismic stations, it's the most immediate method to identify the propagation.

Oil and gas exploration boats have sound sources too. Some years ago they were repetitive sudden gas expansions, that is, mini explosions. This would include the frequency band of the seismic stations. Maybe such means are available at the Falklands presently, or somewhere in the region.

Edited November 29, 2017 by Enthalpy

[Endy0816]

On 11/26/2017 at 6:52 AM, swansont said:

That the "routine" emergencies are not the cause could mean that drills are indeed effective. You know how to react, so if the magnitude of the problem is small enough, there is minimal impact.

More like those particular scenarios have become themselves less common. Two of about nine incidents were something we'd trained for. Not less training, but diversified training would have been useful IMO.

On 11/28/2017 at 5:31 AM, DrP said:

I believe it does. My Uncle was in a submarine for the whole of WW2 - he had some amazing stories. Being honest it sounded pretty hellish.

Been awhile. There's still some negative aspects but there have also been steady quality of life improvements.

On 11/27/2017 at 3:57 PM, Enthalpy said:

Enrique Balbi, spokesperson of the Argentine Navy, excluded today that the own weapons could destroy the ARA San Juan, because the submarine didn't carry combat torpedoes:
http://www.laprensa.com.ar/459901-La-Armada-dijo-que-sigue-sin-ser-detectado-el-ARA-San-Juan-y-suman-medios-a-la-busqueda.note.aspx
Además, descartó que esa explosión o implosión pueda haber sido causada por armamento propio, ya que el San Juan "no tenía torpedos de combate".

Single pressure-resisting volume too, if I read the drawings properly.

This makes more desirable an explanation of the multiple bangs heard at Ascension. And more wanted, the records at Tristan da Cunha (if any) and at Crozet.

It would help quench alternative explanation attempts, which include even an attack:
Consultado sobre versiones que circulan en redes sociales, el portavoz naval subrayó que "ningún indicio" indica que "haya habido un ataque exterior al submarino ARA San Juan".

They are only showing the crew areas. Probably out of concern for the sister ship. They'd have some kind of air tanks onboard as well.

Don't know if it was that though.

 

Any updates otherwise?

[Enthalpy]

Updates yes, but not nice ones... The Navy told after two weeks that hope to find survivors had vanished, so the Government changed the operation to a search of the boat without rescue. The rescue means and teams have left, the ones for search continue, including international ones. Half a dozen potential objects were noticed, about three have been visited and were not the Ara San Juan, the others must wait for better weather.

100kg of explosives were detonated at 40m depth in the search zone to calibrate the seismic sensors that registered the previous explosion, as suggested on November 29 in the present discussion.
https://www.clarin.com/sociedad/submarino-ara-san-juan-detonaron-dinamita-agua-comparar-dimension-explosion_0_HkOVtPm-f.html
The newspaper tells "to compare the size of the explosion", which is already interesting to know. I suppose the experiment also let calibrate the propagation times and determine more accurately where the November 15 explosion happened. The newspaper doesn't report that, which would be a bit technical for the public.

[mistermack]

I seem to remember that the sub radioed about problems before the event, and then that the problems were resolved and they were proceeding to a base.

If that's true, it pretty much rules out the remote possibility of an attack sinking the sub. North Korea is the only country I can think of that would be in the frame for that, and they are a long way away.

I just checked wikipedia, and it doesn't make much of the report. It says that the day before, the sub leaked water into the forward storage batteries, igniting a fire. The crew put the fire out, and the sub continued on it's way, using the rear batteries. I would say that that has to be a major candidate for the cause of the loss, and that there is more that they aren't saying. 

You would think that after a problem like that, in peace time, the safest thing would have been to continue on the surface using diesel power  and with plenty of ventilation.

[DrP]

On ‎02‎/‎12‎/‎2017 at 10:33 PM, Endy0816 said:

Been awhile. There's still some negative aspects but there have also been steady quality of life improvements.

I was thinking more about the combat situations where they had to go silent and hide....  just sat there in silence and darkness for hours on the seabed waiting for the frigates to bugger off. Depth charges exploding nearby in the water rocking the stationary sub. Big muscular men crying like scared babies and children and praying aloud in the darkness from panic.  Maybe modern warfare is different.

It is a sad situation but it looks like the sub has gone and the crew lost.  

 

[StringJunky]

2 hours ago, DrP said:

I was thinking more about the combat situations where they had to go silent and hide....  just sat there in silence and darkness for hours on the seabed waiting for the frigates to bugger off. Depth charges exploding nearby in the water rocking the stationary sub. Big muscular men crying like scared babies and children and praying aloud in the darkness from panic.  Maybe modern warfare is different.

It is a sad situation but it looks like the sub has gone and the crew lost.  

 

The BBC infographic I saw suggested there was a 5000ft depth at its last known location, which is beyond the tolerance of a sub hull if it lost bouyancy, I think.

[Endy0816]

On 12/5/2017 at 11:54 AM, Enthalpy said:

Updates yes, but not nice ones... The Navy told after two weeks that hope to find survivors had vanished, so the Government changed the operation to a search of the boat without rescue. The rescue means and teams have left, the ones for search continue, including international ones. Half a dozen potential objects were noticed, about three have been visited and were not the Ara San Juan, the others must wait for better weather.

Sad, hopefully they'll find something.

2 hours ago, DrP said:

I was thinking more about the combat situations where they had to go silent and hide....  just sat there in silence and darkness for hours on the seabed waiting for the frigates to bugger off. Depth charges exploding nearby in the water rocking the stationary sub. Big muscular men crying like scared babies and children and praying aloud in the darkness from panic.  Maybe modern warfare is different.

Subs are used more for intelligence gathering, operating as a part of a carrier group or remaining on standby with the Nukes now.

Do still rig for Ultra Quiet on occasion. About the same procedure used for night. Turn off the lights in Control, dim others nearby. Only big difference if you are not on shift(6 hours) you should be in your rack. Sleep, read, play on your devices; fond memories.

It's mostly smaller guys actually. Physical fitness standards + narrow passage ways and overhead pipes. We generally try and train not to panic though. Rapid response is more useful. Most emergencies are time critical.

 

1 hour ago, StringJunky said:

The BBC infographic I saw suggested there was a 5000ft depth at its last known location, which is beyond the tolerance of a sub hull if it lost bouyancy, I think.

Yeah, probably was beyond crush depth for that sub. If I recall correctly, subs used to do that on occasion if it was shallow enough. Think some ended up stuck or damaged as a result, so they moved away from it.

 

6 hours ago, mistermack said:

I seem to remember that the sub radioed about problems before the event, and then that the problems were resolved and they were proceeding to a base.

If that's true, it pretty much rules out the remote possibility of an attack sinking the sub. North Korea is the only country I can think of that would be in the frame for that, and they are a long way away.

I just checked wikipedia, and it doesn't make much of the report. It says that the day before, the sub leaked water into the forward storage batteries, igniting a fire. The crew put the fire out, and the sub continued on it's way, using the rear batteries. I would say that that has to be a major candidate for the cause of the loss, and that there is more that they aren't saying. 

You would think that after a problem like that, in peace time, the safest thing would have been to continue on the surface using diesel power  and with plenty of ventilation.

They do seem to be looking at the batteries as a primary cause now. Know that it wouldn't have helped matters if something else happened too though. Hydrodynamic lift and pumping water are both tied to having power. Pressurized air backups for both but if one of them wasn't working as well could end up going down.

[mistermack]

On 12/12/2017 at 10:17 PM, Endy0816 said:

They do seem to be looking at the batteries as a primary cause now. Know that it wouldn't have helped matters if something else happened too though. Hydrodynamic lift and pumping water are both tied to having power. Pressurized air backups for both but if one of them wasn't working as well could end up going down.

You would think that in a system of multiple batteries, there would be plenty of backup circuits available. There would be no need to put all the eggs in one basket on vital systems. The most vital ability of any sub would be to surface in an emergency, and I can't imagine them designing a system that is anything other than foolproof, or very nearly. Of course, if something explodes and allows a serious inflow, then that would override the ability to surface.

Or, fumes might knock out the crew, and cause an uncontrolled descent. But even that could be guarded against. You could have something like a dead man's handle like they have on trains, that would cause the sub to surface if it got no input from the crew.

[swansont]

2 hours ago, mistermack said:

You would think that in a system of multiple batteries, there would be plenty of backup circuits available. There would be no need to put all the eggs in one basket on vital systems. The most vital ability of any sub would be to surface in an emergency, and I can't imagine them designing a system that is anything other than foolproof, or very nearly. Of course, if something explodes and allows a serious inflow, then that would override the ability to surface.

Redundancy of systems is an important design criterion, but it's also in competition with limits on size and weight, so there are always going to be trade-offs.

There are spaces in subs that (in some designs) if flooded past a certain point, or multiple spaces flood, it is impossible to surface.  

 

On 12/12/2017 at 5:17 PM, Endy0816 said:

It's mostly smaller guys actually. Physical fitness standards + narrow passage ways and overhead pipes. We generally try and train not to panic though. Rapid response is more useful. Most emergencies are time critical.

I'm not one of the smaller guys; my day on a sub felt quite cramped when I was in some of the spaces.

[Endy0816]

Might be able to do something based on depth/pressure. Newer subs may even have that now. Only issue would be if there is anything above(Greenville).

There is Emergency Air. I would say normally it'd take alot to incapacitate everyone near the Chicken Switch. San Fran did almost have that occur though having suffered multiple crew injuries(seamount collision).

9 hours ago, swansont said:

I'm not one of the smaller guys; my day on a sub felt quite cramped when I was in some of the spaces.

Could've been worse. You could have been a football player touring. Was the most ridiculous thing ever. They were pretty ecstatic, but definitely had to crouch and walk down the passageway sideways at times.

Captain right, Jeff Hartings and John Abrams left.

Serious have seen guys deck themselves on those pipes. Hopefully you had fun though. They are cool.

 

I do hope they find out what happened. Normally they always do but may take awhile.

[Enthalpy]

Found.

pagina12.com.ar - pagina12.com.ar
lanacion.com.ar - lanacion.com.ar
clarin.com - clarin.com - clarin.com
laprensa.com.ar - laprensa.com.ar

The pressure-resisting hull is in one part, with no significant hole, and squashed. Interpret: the boat sank from internal causes. The hull was guaranteed for 300m depth, it imploded a bit before touching the ground at 900m.

Edited November 18, 2018 by Enthalpy

[StringJunky]

15 hours ago, Enthalpy said:

Found.

pagina12.com.ar - pagina12.com.ar
lanacion.com.ar - lanacion.com.ar
clarin.com - clarin.com - clarin.com
laprensa.com.ar - laprensa.com.ar

The pressure-resisting hull is in one part, with no significant hole, and squashed. Interpret: the boat sank from internal causes. The hull was guaranteed for 300m depth, it imploded a bit before touching the ground at 900m.

That's how I see it. The boat lost its buoyancy control and the hull then failed somewhere around its absolute maximum depth limit.

Edited November 18, 2018 by StringJunky

[Enthalpy]

The control loop includes the crew, which has several means to act on the depth of a submarine. Ballasts are one means. The flaps are an other if the boat moves. At least some submarines have weights than can be dropped if everything else fails. But (all?) these need power on board and some valid crew members.

A valid explanation must tell why none of the control means brought the submarine to the surface.

[StringJunky]

40 minutes ago, Enthalpy said:

The control loop includes the crew, which has several means to act on the depth of a submarine. Ballasts are one means. The flaps are an other if the boat moves. At least some submarines have weights than can be dropped if everything else fails. But (all?) these need power on board and some valid crew members.

A valid explanation must tell why none of the control means brought the submarine to the surface.

i wouldn''t have thought it would be wise to go below periscope depth and have to use the batteries for propulsion and energy needs when water shorted a battery earlier.

Edited November 18, 2018 by StringJunky