Argentinian Submarine Lost? News?

[HalcyonDaze]

Is it a good idea to keep operating/diving the sub with a known hull water penetration ?

Was going to post a reply, but Bob covered it far better than I did. USS Cochino's loss was also the example going through my mind; reading that report it seems the sea conditions paled in comparison to what the search vessels looking for the ARA San Juan have been dealing with (10-meter waves and 100-knot winds)

 

[Akimbo]

Was going to post a reply, but Bob covered it far better than I did.

I agree, @Bob DBF's post was excellent and provided a lot of practical insight. This may also give some insight into the complexities involved with submarine disasters. The USS Thresher (SSN-593) was the first US nuclear sub the was lost. There is also relatively a lot known about the cause because she was on sea trials, was closely being monitored by Submarine Rescue vessel, and the debris field was surveyed. The likely cause was a seawater leak near the max working depth that happened to hit critical electrical control systems which shut down the reactor. That left her virtually dead in the water and she sank to crush depth. This is an over-simplification; no question it was much more complex than that and the entire crew was engaged in damage control to the end.

Once you see the complexity and compactness inside a sub you can appreciate how difficult (or impossible) it can be for designers and crew to anticipate every possible failure, even before factoring in battle damage. Short of gross negligence or criminal intent, the probability is incompletely-informed judgements combined with one or more systems failure conspired to kill the boat.

 

[Bob DBF]

The likely cause was a seawater leak near the max working depth that happened to hit critical electrical control systems which shut down the reactor. That left her virtually dead in the water and she sank to crush depth. This is a simplification; no question it was much more complex than that and the entire crew was engaged in damage control to the end.

That was what caused the casualty, what killed the boat was reactor recovery procedures, there was no way, at that time, to shorten the startup time or draw steam for power, before the reactor was started. This left an emergency blow, one or more of the valves iced and froze shut which not only robs it of lift, but will also change the trim and possibly spill air out of other ballast tanks through the free flooding areas.

Over time, these problems were addressed, however the crew, 12 Officers and 96 men, 4 shipyard officers and 17 civilian technicians perished for the knowledge. My uncle was bumped off that trip by his boss who was lost with the boat. I still lived the dream and joined the Navy two years later and volunteered for submarines and served on them.

...the probability is incompletely-informed judgements combined with one or more systems failure conspired to kill the boat.

The big problem is that there a lot of areas that can't actually be inspected directly. You have to use secondary clues and those may be wrong initially if there are multiple casualties. The battery well is small and sealed to keep seawater out and direct H2 gas so it can be properly dissipated, there is no way to see if it is flooding untill it's too late if there is no alarm, which may happen in an electrical casualty.

I keep coming back to batteries as they are the most dangerous piece of equipment in the boat. With the report that three of the four batteries were off line due to problems, it puts a lot more stress on the operational battery, and a question mark on what is actually happening with with the other three.


Bob

 

[Steve_C]

Listening to this discussion of making difficult decisions with limited knowledge I recall a discussion with my brother who was a petroleum engineer on an offshore oil platform. He said that sometimes you could see the mud level rising. I asked what that meant. He said either there was a gas bubble coming up and you needed to add more mud or you were adding mud too fast and you needed to add it more slowly.

 

[Norwegian Cave Diver]

I'm not a submarine guy - but here is my question...
CNN is reporting that the sub reported taking on water thru the snorkel tube. This suggests it was at the surface running the desiel engines and charging its batteries. Too much water goes down the snorkel and floods a battery compartment. They report a fire and have switched to a different set of batteries. Also reported is that would have caused them to run underwater at half speed. Would it be standard protocol at that point to head for shallower water? Presuming the water they were in was deeper than their crush depth?

 

[Akimbo]

Would it be standard protocol at that point to head for shallower water? Presuming the water they were in was deeper than their crush depth?

Logical but the actual protocol is totally dependent on the Argentine Navy, probably with input from the yard the built the boat. Unfortunately, it is overly speculative to get too specific on technical or operational questions about much of anything based on news reports. Taking on water can mean anything from a slow leak to a flood, or be completely wrong in the first place. It is even more difficult since it appears to be a small German-made sub that very few people in the world have direct knowledge of. At best we can provide some general insight that may or may not apply in this case.

 

[HalcyonDaze]

Logical but the actual protocol is totally dependent on the Argentine Navy, probably with input from the yard the built the boat. Unfortunately, it is overly speculative to get too specific on technical or operational questions about much of anything based on news reports. Taking on water can mean anything from a slow leak to a flood, or be completely wrong in the first place. It is even more difficult since it appears to be a small German-made sub that very few people in the world have direct knowledge of. At best we can provide some general insight that may or may not apply in this case.

There's also the issue that, based on what we've heard so far, the sub is running on reduced battery capacity and can't surface to use the diesel engines. I doubt she was running at "half speed;" modern diesel-electric subs can do 20-25 knots submerged but that will run the batteries flat in a matter of hours. I don't see the submerged endurance figures for the Thyssen TR-1700 listed, but another common German design of similar tonnage, the Type 209, has a reported submerged range of 400 nmi at a speed of 4 knots. Odds are more likely that she was crawling along at her best sustained cruising speed and trying to head straight for home port.

As far as the batteries - the information on Wikipedia says the TR-1700s were built with eight 120-cell batteries, which I presume would be split between the fore and aft compartments.

One of the other arguments against running on the surface, especially in bad weather, is that even on the surface it's not easy to spot a sub in poor visibility. More than a few subs have been mowed down by a passing ship while surfaced or at periscope depth.

 

[Bob DBF]

Taking water through the snorkel means it's f'n rough out and, if the system is similar to others, the head valve, which closes to prevent flooding when the snorkel goes under, is having problems. The drain for the snorkel is substantial but can't handle a major flood, which on a boat I was on wiped out some fans and electrical equipment when it overflowed the drain.

I doubt if any flooding from the snorkel made it into the battery. Batteries are well protected and if flooded would be producing chlorine gas, which the skipper would have reported. The report said battery system, which means switches, wireing, and controllers which have been known to overload and burn. The battery compartments are marginally larger than the battery, it is used to keep the batteries in place and has barely enough room between the battery and overhead for a man to crawl to check gravities on the cells.

If the skipper was concerned that the boat was in any imminent danger, he would head for shallower water, but what was reported would be a day at the office on a diesel boat in bad weather. Things go wrong on submarines, you evaluate the problem, solve it, and move on. Sometimes you can't see the big picture untill it's too late. Fortunately, most of the time submariners bring back the boat dispite adversity.

Reducing the speed conserves the battery, and considering the weather, they probably did not want to be on the surface untill it calmed to do a charge. Also it gives time to make repairs and possibly get the other batteries on line.



Bob

 

[Bubblesong]

So this:

Argentina ends missing sub rescue mission

 

[emoreira]

So this:

Argentina ends missing sub rescue mission

With this the Argentine Navy declared that all members of the crew are death. The operation goes on but trying to find the rests of the sub without any hope to find any one alive. Now it's a recovery mission.