My pop was a missle fire control guy for the subs for developing early Polaris and Posieden missles. It wasn’t until he retired that he actually sailed on them for sea trials out of Groton. We worried for him . Sadness for the bubbleheads that did not return this past week. Best of the best sailors Our heart goes out to their loved ones.
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Not surprisingly, age becomes a question:
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Absolutely Bug.
Interesting images in the article.
Fueled by a morbid fascination, I have been looking up pictures of submarine wrecks that have undergone crush. Having seen pictures of contact mine damage to a pressure hull, I rather naively believed they’d be squished flat, somewhat like if you stepped on an empty coke can, but it turns out that real life is far more chaotic than that.
They end up blown apart and fragmented, with damage reminiscent of some great internal explosion. The one common denominator seems to be flattened pipes in the debris field. As for just how ambiguous the wreckage turns out, witness the internal dispute in the USN over wether the USS Scorpion was blown up from an internal explosion, an external torpedo hit, or simply fell below crush depth.
I don’t really understand how this happens, but suspect that it has to do with the inertia of water that is forced in through the initial breach.
Submarine hull life is estimated by submergence cycles, each time a submarine submerges and goes deep it shortens its hull life.
This explains a lot. I wonder whether they were aware of this…
Question:
What happens to a submarine when it goes beyond its maximum depth?
Answer:
Kevin McAllister Retired U.S.Navy Submariner, Golden Shellback:
Unfortunately this is not a cut and dry answer. Because it depends on how much the submarine exceeded its max depth. Also it depends on the age of the submarine. Submarine hull life is estimated by submergence cycles, each time a submarine submerges and goes deep it shortens its hull life. Exceeding test depth dramatically reduces hull life, it then becomes a matter of it being economical to keep the submarine active.
Submarines actually have several significant depth numbers, test depth, the depth that a is submarine expected to operationally achieve without any ill effects, when testing and certifying submarine systems exposed to sea pressure it is to this pressure that systems are tested to. So test depth is the pressure that the submarine is tested to.
Then there is the design depth, that is the depth that the submarine has been designed to be able to reach. Next is crush depth this is the depth that it is calculated that the submarine structure and mechanical systems will begin to fail and the submarine be crushed. It is conceivable but unlikely that a submarine could reach this depth and not explosively implode. In WW2 when material science was not as advanced, there were instances of submarines descending to this depth and surviving. Now days I would consider this more unlikely.
Jeffrey Knight, qualified on 4 different classes of U.S. Submarines
All organics will be crushed into fishfood in less then a second…
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The same for aircrafts with the compression-decompression cycles of the body; there may be fatigue cracking of the fuselage too. However, the aircraft will not implode but explode.
Probably a cause for the in-flight transformation of the Aloha B737 into an open-top cabriolet, 33 years ago. This aircraft was always used as island-hopper, with a high cycle number and very short flights.
https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243
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IN MEMORIAM
The Navy Chief of Indonesia officially announced the submarine from submiss to subsunk. They found traces of the wreckage of the submarine within 10 km of the crash site, including parts of torpedo tubes, grease cans, and jainamaz. He confirmed that the wreckage had started floating on the surface as the submarine had completely collapsed due to excessive water pressure. Thoughts and respect go out to these brave sailors, families and fellow Naval comrades. Fair winds and following seas. Rest In Paradise, brothers.
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This seems a bit backwards unless they mean the old time subs were like DC-3s where they were not quite sure exactly how strong to make them and erred on the side of more metal. I guess now if your sub is rated to implode at 754 feet, then they calculated that really well and are not kidding and 753 feet is one foot from death.
The Oberon class submarine HMAS Onslow was taken to near its crush depth by a crew member. Following this she was withdrawn from service and you can go onboard her at the Sydney Maritime Museum. The Oberon class were conventional diesel electric and in their day a very formidable submarine being very quiet.
To a degree, yes. The old fleet subs were made of mild steel and had fairly shallow depth ratings in the neighborhood of 300 or 400 feet. Toward the end of the war they built boats with higher yield steel (HY80 if memory serves) but they were overbuilt by today’s standards. Modern boats are built with HY100 and even in some cases, titanium. Weight is a big issue as is yield strength. A strong heavy hull can’t manage much load but can dive deep but a lighter hull can maneuver quickly and carry a larger load for its size. Just like in aircraft, it’s all a compromise.
Modern designs, materials, and fabrication techniques allow for the incredibly accurate construction required for deep submergence. Precision of hull circularity makes a huge difference in depth capability. The diesel boats I sailed on had hulls close to an inch thick but were peppered with doublers and multiple inch thick welds on hard patches (for battery and machinery access) along with an a great number of large penetrations so precision was not exactly to modern standards. By the time those boats were retired they were rated at only 300 feet. I always thought that was amusing because it meant the boat was rated for less than its own length. Not to mention the things leaked when it rained … but when submerged the packing on the leaky penetrations would seal very well. It made for good bar stories.
After going back to the real world I worked for a company that designed, built, and operated deep diving manned submersibles for military and oil field work. The boats were rated for 2000 meters and we regularly dived very close to that while supporting a drill ship off West Africa and doing work on transatlantic cables. The hulls were made of spherical HY100 steel, machined to a very high tolerance inside and out. That design was very critical in terms of weight and we used large volumes of syntactic foam to achieve a balance between weight and the amount of hard ballast (water in depth rated tanks) to obtain neutral bouyancy at depth.
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Computers is to “blame” for some of this. Before computers became standard tool to calculate required strength of constructions a large safety factor was applied.
Back in them days (mid-1970s) I was given a guided tour of a newbuilt semi-sub at the building yard in Japan. My guide was a god ol boy that had designer the rig. (The world’s biggest at the time)
He explained his philosophy on strength calculations this way; “I let those young engineers with their fancy computer do their calculation, then I double it”.
PS> He held the title “Dr.Eng.” Some of the rigs he had been in charge of designing exist still. (Not that one)
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Finite Element Analysis - how much metal can we leave off today?
A new theory on the sinking:
The Lombok Strait between the islands of Bali and Lombok is said to be famous for generating intense internal waves on an almost fortnightly basis.
…and yet they deemed it a safe training ground?
Wow, sounds like a “standing wave”. It is hard to imagine that there are currents fast enough in that area to create the phenomenon with enough power to overcome the sub’s propulsion or efforts to stop the descent.
I don’t know how that particular class of boats managed the dive but we used a “negative tank” that when flooded, along with flooded main ballast tanks, would produce negative buoyancy and the boat would submerge. When clear of the surface and stabilized in descent the negative tank would be blown dry and the boat would achieve neutral or slightly positive buoyancy. In that condition it would take considerable force to overcome blowing main ballast and I would think that a standing wave of that strength would be highly visible on the surface.
When such waves are formed in a river the peaks are very obvious as they stand well above the normal water level. When they occur over mountain ranges due to wind flow they create lenticular clouds that are a magnet for sailplane pilots but warn of potential horror for passing powered aircraft.
I’d never heard of this phenomenon under water. This NASA photo suggests that the internal wave trains could act like an upside down lenticular cloud pushing a sub deeper.
But the very definition of a wave form is that it is comprised of peaks and troughs. You can’t have movement to the trough without movement toward the peak.
There is no upside down because the upside and downside coexist, that is what makes it a wave.
I know nothing about internal wave trains in the ocean but I think it is safe to say that a wave is a wave and if the period or frequency is low (a swell) then regardless of amplitude it sounds incredible that one could overcome any actions to counter it by the sub crew. If the frequency is high (steep breaking wave) then it doesn’t seem possible for the wave to have much time to force the boat deeper.
The idea is interesting and I hope someone with real knowledge chimes in here or there is more published to expand on the risk to a submerged vehicle.
Within a wave, individual water molecules move in circles that get smaller with depth and eventually stop altogether. Boats or bottles or other debris floating on the surface don’t go anywhere either, but simply bob up and down. The only thing waves do transmit across the sea is energy. So I do not see how a wave, also an internal wave, can pull down things whether it is a plastic bottle or a submarine.
Water molecules are moving in circles which are becoming increasingly smaller with water depth. What you need to move objects underwater is current, not waves. It is perhaps possible that under special circumstances underwater currents can exist, probably both horizontal and vertical currents.
I think it’s possible if the effect is deep enough so it doesn’t affect the surface. I was imagining the overall effect of encountering a sinking underwater wave train rather than the wave structure. Entering a lenticular cloud at a low edge on the lee side of a mountain would push an aircraft down which was the effect this sub would have encountered for it to plunge that severely. I’m visualizing the downward current to be the source of the downward force rather than by individual waves in the pattern. When you scuba dive, it’s not unusual to encounter currents different than those on the surface