Submarine question

[joe123321]

Can you get the bends in a submarine? say your in a sub that the inside is normal atmospheric pressure, down at a depth of 400 meters and the ship surfaces very quickly, will you get bent?

 

[Oldsarge]

Can you get the bends in a submarine? say your in a sub that the inside is normal atmospheric pressure, down at a depth of 400 meters and the ship surfaces very quickly, will you get bent?

Nope. The inside of the sub is, as you say, at normal atmospheric pressure so the nitrogen can't be driven into your bloodstream. If it isn't driven in, it can't bubble out.

 

[joe123321]

Ok cool

Say the sub is at 50 meters and you try to leave the sub and swim to the surface would you get it then? Would the huge pressure change kill you?

 

[apneaboy]

Go to the SETT in Gosport, they do training drills from 30 metres to simulate that potential problem (well actually i don't think they do exactly that now)

The best thing to do if your thinking about getting your own sub is don't drive it too fast and don't get out of it.

Laters

 

[Lazuli]

Have a look at this book extract. It seems that the bends and air embolism are serious hazards associated with escape from a disabled (or possibly functional) submarine at depth. There are many variables it seems.

 

[Lazuli]

Check out this homebuilt submarine.

 

[spaghetti]

Coltri Sub in Italy (a pretty famous scuba gear manufacturer) makes custom submarines.
They cost about 20 k euro (cheaper than a Ford Mondeo!).
It's out of catalogue, made only on demand, but you may contact Aerotecnica Coltri and make an order with your own specifications (I don't think they make it with leather armchairs and champagne coolers, but then why not?). Pic attached:

 

[apneaboy]

Coltri Sub in Italy (a pretty famous scuba gear manufacturer) makes custom submarines.
They cost about 20 k euro (cheaper than a Ford Mondeo!).
Pic attached:

I bet it would be easier to find a parking space than a Mondeo too.

 

[Old Man Dave]

Ok cool

Say the sub is at 50 meters and you try to leave the sub and swim to the surface would you get it then? Would the huge pressure change kill you?

Inside the sub is normal surface pressure and the hull of the sub protects you. If it broke open at 50 metres and you were suddenly outside you'd be f*cked. The pressure would crush your lungs and other air chambers. However you could escape from a sub at 50 metres using its air lock.

You go in the air lock. The air lock is pressurised to 50 metres water pressure. The outer door opens and you go up. As your lungs etc are pressurised to the depth of water no crushing. However you would need to equalise your lung pressure to the water depth as you go up. If you were wearing beathing aparatus you'd be okay. No bends and no embolism. If you were heading up on one breath its theoretically possible to breath out slowly and release your lung pressure but most likely you'd get an embolism or suffer anoxia and black out. You might make it up alive but not in too good a state of health - no bends though unless you'd sat in the pressurised air lock too long.

Lots of ifs and buts with this question although the basic physics are fairly well known.

Assume you're not a scuba diver as if you were you really need to understand the physics of pressure and depth. I'm afraid too many scubbies don't.

Dave.

 

[azapa]

good answer Dave, i posted that question (escape from a sub at about 30/40m) a while back here and was puzzled by the lack of clear answers. where were you that week?

 

[joe123321]

Inside the sub is normal surface pressure and the hull of the sub protects you. If it broke open at 50 metres and you were suddenly outside you'd be f*cked. The pressure would crush your lungs and other air chambers. However you could escape from a sub at 50 metres using its air lock.

You go in the air lock. The air lock is pressurised to 50 metres water pressure. The outer door opens and you go up. As your lungs etc are pressurised to the depth of water no crushing. However you would need to equalise your lung pressure to the water depth as you go up. If you were wearing beathing aparatus you'd be okay. No bends and no embolism. If you were heading up on one breath its theoretically possible to breath out slowly and release your lung pressure but most likely you'd get an embolism or suffer anoxia and black out. You might make it up alive but not in too good a state of health - no bends though unless you'd sat in the pressurised air lock too long.

Lots of ifs and buts with this question although the basic physics are fairly well known.

Assume you're not a scuba diver as if you were you really need to understand the physics of pressure and depth. I'm afraid too many scubbies don't.

Dave.

Thanks for all the answers everyone

So, the pressure in your lungs would not be able to counter the outside pressure if you were suddenly thrown out into the water... But then How is it possible to take a breath on the surface and dive down to 50 meters? is it just that the change is gradual so you body adjusts?

 

[trux]

So, the pressure in your lungs would not be able to counter the outside pressure if you were suddenly thrown out into the water... But then How is it possible to take a breath on the surface and dive down to 50 meters? is it just that the change is gradual so you body adjusts?

You are not thrown out suddenly from a submarine. Either it breaks, and the water penetrates inside compressing the available air to ambient pressure, or you go to the escape lock, which will be pressurized to the ambient pressure too before opening. Hence you start your escape with air under high pressure in your lungs. Assuming you escape from 50m, it is 6 bars. That's also why you have to exhale all way up, otherwise the pressure will cause embolism and/or rip your lungs apart.

 

[joe123321]

Oh I see, thanks. But if you took a breath, then it broke and then you swam out you could do it.

 

[trux]

Oh I see, thanks. But if you took a breath, then it broke and then you swam out you could do it.

It depends what you mean by "broke". If it means that it suddenly explosively completely opens, then you would not survive it. If you mean that it starts leaking and fills with water compressing the available air, then yes, you can theroretically do it, but of course there are many other factors too, like the temperature, possible injury, time spent in the high presure, panic, sufficient opening to get out, etc.

 

[Oldsarge]

The Navy ran (and may still run) classes in submarine escape for all the undersea sailors. They involve doing just what has been described above. However, I am unaware of any submarine accident where the technique was employed and worked. The only time sunken sub crews were ever saved, they remained in the hull until a rescue craft came for them. And that, BTW, doesn't happen very often. I believe it worked once . . .


So you can add that to my claustrophobia for being a good reason to never go down in a sub!

 

[trux]

I think there were plenty of successful escapes in the history, although Oldsarge is certainly right that the success rate is rather low due to a number of factors.

One of the first recorded successful escapes (but only from 10 meters) is described in this document:
Submarine Escape from 600 ft Using Rapid Compression and Buoyant Ascent

... To understand how this system evolved, it is easiest to begin with one of the earliest successful escapes when, in 1916, HM Submarine E.41 sank after a collision. Most of the crew managed to escape through the conning tower before she foundered. In previous accidents those trapped below had usually drowned, but this submarine was one of the first to be fitted with water-tight bulkheads, and thus, aft of the flooded compartments, one man was trapped alive in the undamaged engine room. There were only 30 ft of water above him, but he was unable to open the hatch and escape as the weight of water pressing down on it was over 7 tons. He realized that the only way to escape was to flood his compartment with sea water until the internal pressure equalled -the external pressure. This he did, but each time he tried to open the hatch a bubble of air escaped and the hatch slammed shut again. After several desperate attempts, he was eventually successful and found himself floating to the surface in a bubble of air Stoker Petty Officer Brown was thus the first man of the Royal Navy to make a successful escape from a sunken submarine. His action illustrates the basic principle of all underwater escape, the need to raise the pressure of the escape compartment to that of the sea outside. It is this exposure of man to their raised environmental pressure that introduces the dangers of such methods of escape.

I also remember that there was another submarine accident in Russia, shortly after Kursk - a decommissioned submarine sank while being towed. I believe one of the guys inside the submarine managed to escape (if I remember well). I do not know though from what depth it was. Perhaps the sub was not even completely underwater yet. I cannot locate the information right now.

You can read some interesting info about submarine escape and rescue techniques for example here:
http://www.jmvh.org/upload/pdf/8a6125460193049cf9ea4f7e7980c414137d1a96.pdf
[ame="http://en.wikipedia.org/wiki/Submarine_Escape_Immersion_Equipment"]Submarine Escape Immersion Equipment - Wikipedia, the free encyclopedia[/ame]
Submarine Escape and Rescue

 

[Old Man Dave]

Thanks for all the answers everyone

So, the pressure in your lungs would not be able to counter the outside pressure if you were suddenly thrown out into the water... But then How is it possible to take a breath on the surface and dive down to 50 meters? is it just that the change is gradual so you body adjusts?

Most people can't do that. You are right that gradual compression of the lungs and air chambers of the body would enable your lungs to be compressed. However a lung full of air compressed by 30 metres of water pressure is actually equivalent to an empty lung. Beyond 30 metres of water pressure your lungs become smaller than when they are normally empty. This is possible because "empty" lungs actually contain about a quater to a third of their volume. You never normally completely deflate your lungs. So if you have a full lung of air at surface pressure you can compress it with equivalent of 30 metres water pressure and it will be like an empty lung and no damage (if done slowly). However pressure of deeper than 30 metres for a "normal" person results in lung damage. Deep divers train thair bodies especially thair lungs to compensate but bet they struggle to get life insurance.

Dave.

 

[Almostafish]

One small thing here, if the sub did " Break " you would be fried as the volume of air in the sub became affected by the water pressure and was compressed thus heating it up. Grabbing a breath is not an option! The deepest unclassified escape from a sub according to the wall at the SETT tank in Gosport is about 700ft but that was with all sorts of Gucci kit..

 

[Lazuli]

I also remember that there was another submarine accident in Russia, shortly after Kursk - a decommissioned submarine sank while being towed. I believe one of the guys inside the submarine managed to escape (if I remember well). I do not know though from what depth it was. Perhaps the sub was not even completely underwater yet. I cannot locate the information right now.http://www.subescapetraining.org

That event was very, very sad indeed. My heart goes out to the families of the nine who perished. It was the rotten hulk of the K-159 and it sank with a fuelled nuclear reactor. Crazy.