Indonesian navy submarine found split into three on sea bed (BBC)

[eppur_se_muova]

An Indonesian navy submarine that sank off the coast of Bali on Wednesday has been found split into three pieces on the sea bed, officials say.

All the vessel's 53 crew have been confirmed dead.

Navy officials said they had received signals from the sub's location more than 800m (2,600ft) deep early on Sunday.

An underwater rescue vehicle loaned by Singapore was sent down to get visual confirmation of the wreckage.

The KRI Nanggala disappeared after requesting permission to dive during a torpedo drill. The reason for its sinking is not yet clear.
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more: https://www.bbc.com/news/world-asia-56879933




Cause still not known, but it is now clear the failure was catastrophic.

[Arkansas Granny]

1. I hope all aboard died quickly with little suffering.

[ProfessorGAC]

2. That's Likely The Case

They are at 2,600 feet below sea level.
Every 32 feet is 14.7 pounds per square inch. That's around 80*14.7, or 1,176 psi.
Like being rolled over by a steamroller, in a split second.
The article doesn't give an estimate on how deep they were when the disaster occurred; only that they were running torpedo drills.
A 40 year old sub probably isn't bound to run drills at periscope depth.
And, the crush damage being such that the ship broke into 3 pieces suggests they were quite deep.
I think your hope that they died quickly is more likely than not.

[Irish_Dem]

3. I do too. They probably drowned quickly with that kind of massive hull breaches.

[NutmegYankee]

5. I doubt they drowned.

The method of death is usually an implosion that sends a shock wave through the ship as if the crew was standing next to a bomb. It's usually instantaneous.

[Irish_Dem]

7. That makes sense. Yes the death would have been quicker that way.

Thank goodness.

My uncle was killed in WWII on the USS Meredith. It was very heavily bombed and the ship went down quickly.
We hope he was killed right away and did not suffer.

[Irish_Dem]

4. How and why does a submarine break into three pieces?

[NutmegYankee]

8. After collapse depth, the hull cannot withstand the force of the seawater squeezing it.

The frames buckle and the seawater punches in with such a pressure increase that the air inside accelerates like in a bomb blast. The middle portion probably failed and the other compartments separated. While there can be many causes, such as an uncontrolled flooding casualty that caused the boat to get too heavy and sink, it's possible at 40 years old that metal fatigue was the cause. Every dive is a cycle of stress and like a coat hanger bent back and forth, it finally gives way.

[Irish_Dem]

9. So it probably it flooded, sank to collapse depth and broke apart?

And the flooding was most likely due to old age of the metal frame?

My father was career Air Force, so I understand a bit better about how and why planes go down.
But I am clueless about naval craft. But an aircraft could explode for similar kinds of reasons.

At any rate, I am glad the crew did not suffer.

These old subs should be destroyed at some point, not stay in active duty use.

Thank you Nutmeg for the explanation.

[NutmegYankee]

10. It might not.

A flooding casualty would add tons of seawater to the boat, causing it to sink lower in depth. The crew would try to surface as soon as possible. While surface ships always seek to maintain a positive buoyancy, submarines try to maintain a neutral buoyancy to maintain depth. Extra weight will disrupt that balance. Any flooding event has to stopped quickly or the submarine can sink past its crush depth. So that’s one possible reason.

A separate reason would be catastrophic hull failure because of fatigue. That probably would have been sudden with no hope of responding to it by the crew.

[Irish_Dem]

11. But wouldn't a hull failure mean flooding?

I think you are meaning that there is a difference between a typical flooding situation and a catastrophic hull failure?

[NutmegYankee]

12. A catastrophic failure would be an implosion.

A flooding casualty would be a pipe weld failure or a bolted joint letting go. If unstopped, it will flood and equalize the submarine interior with sea pressure and the hull would not implode. This could happen if the sub sank in shallow waters.

In deep ocean, the flooding event, if uncontrolled, would cause the sub to go below crush depth where it is then smashed by the pressure. What air remains inside is accelerated like an explosive shock wave, killing everyone instantly.


Argentina lost a sub to this a few years back. This video illustrates the sudden catastrophic failure.

[Irish_Dem]

13. OK, I finally see the difference. Unbelievable.

The implosion, good god. It is just horrific. It literally breaks the sub into pieces.

With the catastrophic failure, sailors die instantly from the shock wave.
That is the best way to go I think.

So my uncle who died on the USS Meredith could have been killed by enemy bombs or gunfire right off the bat.

The ship sank quickly, I think like in 10 minutes I read. Or he could have died by the initial flooding or by the implosion after it sank below crush depth. I don't know how long it takes a ship to sink to crush depth. I am fairly certain the ship was in deep water.

Of course I could be incorrectly extrapolating from the data you have supplied germane to submarines.

Or some of the sailors lived initially, floating in shark infested waters and got attacked by the sharks.

Thank you Nutmeg for taking the time to explain all of this to me. I was quite curious about the sub situation.
And then it took me to my uncle's death. The family always wondered how he might have died.

And as I said, my dad flew combat in three wars, so I am familiar with how and why planes go down.
But naval ships/subs, I am clueless.

Thank you for your time and valuable information!

[MissB]

6. That's so sad

Glad there is closure though.