One dead, one missing (since found), 300 foot dive - Lake Michigan

[cerich]

yeah but subs are at ambient pressure, not diving

then how do we get out?

 

[Marie13]

If any of you want to “do something”’as a result of this tragedy, a donation to Bruce’s Legacy, the volunteer ROV operator that recovered Jim Winn,, might be something to consider.

Bruce's Legacy - Search and Recovery for Drowned Victims

 

[cerich]

I think that the point was that a CESA from a 300 foot dive would likely involve a lethal amount of decompression stress. The interior of a submarine is 1 ATA, so there is no nitrogen ongassing prior to flooding the escape chamber, right? But yes, once the escapee equalizes to ambient pressure and begins the ascent, it's basically a CESA.

yes.

The post said "If you do a CESA from 300ft you are going to die. Period. There is no other outcome.", the last part is not really true. Do I think that 99% of the time dead is the outcome? Yeah. That said,. it's possible, been done and much deeper as well.

But yeah, tech divers need to sort whatever is going on at depth.

I have personally been on the boat and had a diver bomb 240'ish and immediately loss his crap and do a uncontrolled, exceedingly rapid ride to the roof and not be bent even. He had about 3 mins on the bottom. It was OC,

 

[John the Pom]

then how do we get out?

You wriggle into a little escape chamber, which is then flooded, and you get out when the pressure equalises. For a normal escape, are only at pressure for a short time.

 

[HKGuns]

You wriggle into a little escape chamber, which is then flooded, and you get out when the pressure equalises. For a normal escape, are only at pressure for a short time.

Yep, that is exactly how it works.

 

[JohnnyC]

Guys it was rhetorical, @cerich knows the answer.....

 

[doctormike]

yes.

The post said "If you do a CESA from 300ft you are going to die. Period. There is no other outcome.", the last part is not really true. Do I think that 99% of the time dead is the outcome? Yeah. That said,. it's possible, been done and much deeper as well.

But yeah, tech divers need to sort whatever is going on at depth.

I have personally been on the boat and had a diver bomb 240'ish and immediately loss his crap and do a uncontrolled, exceedingly rapid ride to the roof and not be bent even. He had about 3 mins on the bottom. It was OC,

Yeah, exactly. I know nothing about submarines other than what I read from you guys here, but I'm assuming that N2 loading for someone escaping from a sub would only be a little bit less than someone doing a bounce dive to the same depth.

That having been said, and despite miraculous survivals, you don't need N2 loading to get decompression stress. As we discussed thoroughly in a thread a few months ago, decompression stress results from a rapid change in ambient pressure. It's more likely to cause clinical symptoms with bubbles if your tissues have more N2 in them at the start of the ascent, but that's not necessary. Right now, all of us have some inert gas loading. So escaping a distressed sub, just like a pilot experiencing an explosive cockpit depressurization, can and has caused DCS.

 

[DiveTucson]

From my rEvo diving friends. How much lead does it require if you only have the drysuit? I. E. is the unit on its own negative or positive? The ones I have played with (mini Ti and standard SS) were all noticeably negative on their own.

I would say 8-16 lbs in drysuit depending on suit and thickness of undergarments is not unreasonable.

Being that they were in extremely cold water I would guess more on the upper side of that to compensate for the thick under garments. Most are also using steel cylinders on the unit in that climate etc.

Contrast to that when I dive the unit in tropical places I can dive it with a 3MM suit and AL cylinders with no weight.

 

[cerich]

Yeah, exactly. I know nothing about submarines other than what I read from you guys here, but I'm assuming that N2 loading for someone escaping from a sub would only be a little bit less than someone doing a bounce dive to the same depth.

That having been said, and despite miraculous survivals, you don't need N2 loading to get decompression stress. As we discussed thoroughly in a thread a few months ago, decompression stress results from a rapid change in ambient pressure. It's more likely to cause clinical symptoms with bubbles if your tissues have more N2 in them at the start of the ascent, but that's not necessary. Right now, all of us have some inert gas loading. So escaping a distressed sub, just like a pilot experiencing an explosive cockpit depressurization, can and has caused DCS.

I can likely find references to send you on the escape trials the RN did on submarine escape back in the 70's. If I recall from my submarine days, it got to sub 800fsw range and one or two died and one was permanently paralyzed. The below 600 foot range is where things went from sporty to snowball in hell.

Regardless, survival often happens in really bad circumstances when the person doesn't know they are "supposed" to surely die or they continue to believe they can no matter what. I would rather believe that it's worth trying and die than submit to my fate and surely die. Some decide they are going to die and stop trying and they do die.

 

[cerich]

You wriggle into a little escape chamber, which is then flooded, and you get out when the pressure equalises. For a normal escape, are only at pressure for a short time.

The ascent rate is 6-10 ft a second. At 600 ft which is doable, that is about a 2 minutes ride to the roof. A single man tower escape takes about another 90 seconds to flood and pop the hatch.(single man tower escape you can cycle 8 pers a hour max, no matter how good the guys are at getting in the tower, it just takes time) Once you get out another few to inflate your SES.a compartment flood and depending on how many pers and you could easily be breathing ambient pressure air(and narced to the 11pm in a foreign port for a submariner level) for upwards of 10 mins. Compartment escapes are truly last resort and will end badly for most in the compartment either not getting out or on the roof bent. However better than being in a compartment without an escape tower..which most will be.