Science of the Deep submarine show

[Foo]

Hi,
I hope this is the right place to put this thread. If not, I sincerely apologize. I was just wondering if anyone else happened to catch the Science of the Deep show this weekend on the Science channel? There was an episode about submarines that I actually just happened to turn to in time to see something really interesting: on a military sub, this guy was put into a air lock chamber, where he put a noseclip on and zipped himself into what looked like an orange body bag on his torso. Water was then let into the chamber, it was opened, and the guy shot up to the surface in the bag, finning and breathing normally. The bag was completely inflated when he reached the surface of the training tube/silo. They didn't say how many feet he ascended, but I think it was at least 60 or more, by the markings on the silo as he ascended. They rescued him from the water, unzipped him, and checked for cognition- then i presume they whisked him off to a decompression chamber? The bags are used for emergency/ or attack ascents from depths as much as SIX HUNDRED feet. (!) This may be old news to you, everyone may have a dozen of them at home... But I thought it was very interesting and was wondering if anyone else saw it? I'm wondering what I missed by way of explanation of the dangers to the individual doing this rapid ascent out of a submarine.
Foo

 

[archman]

As I understood it military submarines (maybe all of 'em) operate at sea level atmospheric pressures, hence you can just crank the hatch open when the things surface. So decompression wouldn't be a problem. Neither would embolism, since the air in the sub is already expanded to sea level norms.

I guess a submariner on this board could answer this better than me. I'm not clear about the depth restrictions on these big bags (why they are what they are).

 

[Genesis]

Sounds to me like a way to allow you to breathe on the way up!

Consider this - you're at 1 ATA. They zip you in this bag with a goodly amount of air, then flood the tube. The air collapses (and you had better equalize your ears and FAST!) and then the hatch is opened.

As you rise, the gas expands again, of course. You can breathe for a while, until the air in the case becomes hypoxic. If there is a bleed cylinder in there it could last a while, since the exhaled gas is not lost to the surrounding water.

 

[DA Aquamaster]

I think the training tank is 100 ft deep although there are locks at 25' and 60' so that the trainees can work up to the 100 ft depth.

Historically, escape hatches on subs have used a skirt that is either fixed in place or telescopes down and allows the compartment to flood until the pressure of the trapped air in the upper part of the compartment is equal to the water pressure outside. The crew then go under the skirt, out the hatch, and up along an ascent line. So during an escape the crew is exposed ambient pressure for a minute or two before they start ascending.

At 600 ft this would seem to present some serious oxygen toxicity risks, nitrogen narcosis problems, as well as concerns for DCI following the ascent even with a breif exposure. An airlock could be used but this would require a substantial amount of time to evacuate the entire crew, would require an operable high pressure pump or a substantial air supply to clear the lock for the next set of escapees, and would not reduce the exposure time or narcosis issues substantially at 19 ATA. It really makes me wonder what they use for a breathing mix or whether the advertised 600' max depth is a little on the optimistic side. 300' sounds a lot more realistic.

 

[diverbrian]

As a person who served on a 688 class submarine, I know that those were our "emergency exits" if the worst was to happen. I believe that you are referring to "Steinke Hoods".

Basically you entered the escape truck at 1 ATA. The escape trunk would be sealed behind you and you would "blow and go" into to hood on ascent after the escape trunk was flooded. Remember, the minute that you take a breath at depth, you have to keep breathing or Boyle's Law will be demonstrated with the air embolism. We could launch a life raft the same way. Decompression illness would not be much of an issue as you spent most of your time at 1 ATA. There is a slight pressure change inside the sub as evidenced by ears popping, but it is similar to the pressurized cabin of an airplane. You are not going to restrict your ascent rate to 30 ft./min for this, LOL. But the minute that the escape trunk is flooded you will be at whatever ambient pressure is for that depth, so I would imagine that all of the ear pain issues that we notice when diving would be in full effect. Also, what little decompression issues that you may have would be minor compared to dying of lack of air on a crippled sub

In any event, this was a last-ditch way out of the sub. The guys who went through sub school practiced this in a tower before reporting to the sub. I came in from a different pipeline and didn't get the "joy" of having to go to sub school.

One of the other submariners on this board can correct me if my memory is too rusty, but that is what I remember when they showed me these things and was quickly told that it was unlikely that we would ever use them.

 

[diverbrian]

I think the training tank is 100 ft deep although there are locks at 25' and 60' so that the trainees can work up to the 100 ft depth.

Historically, escape hatches on subs have used a skirt that is either fixed in place or telescopes down and allows the compartment to flood until the pressure of the trapped air in the upper part of the compartment is equal to the water pressure outside. The crew then go under the skirt, out the hatch, and up along an ascent line. So during an escape the crew is exposed ambient pressure for a minute or two before they start ascending.

At 600 ft this would seem to present some serious oxygen toxicity risks, nitrogen narcosis problems, as well as concerns for DCI following the ascent even with a breif exposure. An airlock could be used but this would require a substantial amount of time to evacuate the entire crew, would require an operable high pressure pump or a substantial air supply to clear the lock for the next set of escapees, and would not reduce the exposure time or narcosis issues substantially at 19 ATA. It really makes me wonder what they use for a breathing mix or whether the advertised 600' max depth is a little on the optimistic side. 300' sounds a lot more realistic.

If we used that we weren't concerned about the mix. We only used those if we were going to die if stayed on the bottom. We had less family friendly nicknames for what we realistically thought of our chances for survival if we used them.

 

[DFC5343]

120ft. in New London and the tank in Coronado is 100. I did the free ascent training as part of my time at the sub base in New London. The blisters as they are called are at 25,60 and 100ft. Basicly they take you down in a diving bell. You have a special life jacket on and nose plug. You inflate at depth, 110 and free ascend to the surface. Its called a blow and go due to your exhaling all the way. If insuffecient amount of air is not leaving your mouth, instructors at various depths yank you into on of the blisters and lecture you on the effects of gas embolism. If you make it to the surface you are a human rocket and come out of the water to about your ankles. Awesome ride. The orange suit you saw is the latest version of the once called Momson Lung/Stienke Hood which gave you a chance if your sub became distressed. It also works as an exposure suit for coldwater.

 

[DA Aquamaster]

I know the US Navy is replacing the Steinke hoods with the full body suit to offer better thermal protection in the water and on the surface. The full body suit is also supposed to have it's own built in life raft.

I remember a news article a few years ago about a soviet sailor who survived a deep water escape then spent a couple months in hyberbaric treatment as he was badly bent during the escape.

I think a deep water escape like that would definitely be a last resort.

 

[Genesis]

Kinda like taking a hit of a 50% bottle at 150' - you know it may nail you, but the alternative is that you die for sure......

 

[diverbrian]

Kinda like taking a hit of a 50% bottle at 150' - you know it may nail you, but the alternative is that you die for sure......

For once, Genesis, you and I are in complete agreement!