CCR max depth?

[Bob DBF]

Everybody gets all excited about the max depth of this or that. Any dummy can take a CCR or OC to any fool depth that they want to. That is the easy part, getting your butt back up alive is where the problems generally are. The most important part of these dives is proper planning.

Back when I was serving on submarines, the standard answer to "How deep can you go?" was "All the way to the bottom."

The USS Thresher and USS Scorpion made the point as they were recent at that time.

JARED0425
Is it possible for them to deploy out of the sub at around 1000ft and make a rapid ascent to their target? I would imagine automatic deco, but for how long?

You just bring the sub up to the depth you need for the mission, then they deploy. If they have a mission at 1000', trust me, you don't want to know what they are doing.




Bob
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I have no knowledge of, nor would I discuss if I did have any knowledge of any such event, if it did in fact occur.

 

[Jared0425]

The divers whome were at 1750' used hard hats and a bell. Something tells me that dive did damage to the body.

 

[Garth]

I can imagine discipline and mental preparation are larger than the tool for the job.

 

[fjpatrum]

I can think of a lot of missions the SEALs would be doing at those kinds of depths. Well, several might not really be "a lot" but certainly I have ideas. Working in/with the military for 20+ years gives you some information you sometimes don't really want...

 

[Hatul]

David Shaw died using a rebreather at some 890 feet trying to recover a body in Bushman's Hole in South Africa. The video from his helmet mounted camera is on Youtube

The Last Dive of David Shaw - YouTube

He had some entanglement that he was not able to solve and he was having a lot of trouble breathing. It's believed he was unable to increase his minute ventilation to match the level of exertion and died of CO2 poisoning with an element of nitrogen narcosis.

Dave Shaw died from carbon dioxide black-out - Divernet

The article mentions his breathing problems related to overfilling of his rebreather. Perhaps someone can explain this.

 

[Doppler]

The article mentions his breathing problems related to overfilling of his rebreather. Perhaps someone can explain this.

Before reading the article, I had been told his scrubber may have been improperly filled (packed tightly). This would have made the work of breathing (inhaling and exhaling) difficult and could have resulted in some level of hypercapnia. Then to compound the issue, he may have suffered CO2 break-through... the scrubber could not handle the work-load.


I would caution you though. Most civilian divers and military combat divers are as far apart as a formula one driver is from a guy driving his Honda Civic down I95.

 

[Hatul]

Before reading the article, I had been told his scrubber may have been improperly filled (packed tightly). This would have made the work of breathing (inhaling and exhaling) difficult and could have resulted in some level of hypercapnia. Then to compound the issue, he may have suffered CO2 break-through... the scrubber could not handle the work-load.
.

That makes sense now. By overfilling, in the article, they must have meant overfilling the scrubber.`

 

[fjpatrum]

Before reading the article, I had been told his scrubber may have been improperly filled (packed tightly). This would have made the work of breathing (inhaling and exhaling) difficult and could have resulted in some level of hypercapnia. Then to compound the issue, he may have suffered CO2 break-through... the scrubber could not handle the work-load.


I would caution you though. Most civilian divers and military combat divers are as far apart as a formula one driver is from a guy driving his Honda Civic down I95.

Not to belittle your statement, Doppler, or the combat divers, but would you really consider someone doing a CCR dive to 890 feet for purposes of a body recovery the Honda Civic driver in that scenario? I'd dare say that's more akin to the F1 driver, with the combat divers being, perhaps, more experienced F1 drivers. Just because they are expected to be able to do such things on occasion, doesn't mean combat divers routinely do them. Even amongst the teams there are people who can do those kinds of missions and those who can't.

 

[Centrals]

Dave Shaw had been to that depth before and the unit was working fine.
How many breathers had been to that depth before him? None.
If he did not have to retrieve the body he should had gone beyond 300m by now!

 

[Doppler]

Not to belittle your statement, Doppler, or the combat divers, but would you really consider someone doing a CCR dive to 890 feet for purposes of a body recovery the Honda Civic driver in that scenario? I'd dare say that's more akin to the F1 driver, with the combat divers being, perhaps, more experienced F1 drivers. Just because they are expected to be able to do such things on occasion, doesn't mean combat divers routinely do them. Even amongst the teams there are people who can do those kinds of missions and those who can't.

My analogy was not specifically aimed at David, just a general observation. David was a bit of a wunderkind. He did some extraordinary things in a short time. And perhaps to continue the F1 theme, I wish his race engineer had been a little more firm about preserving the tires for the last few laps.


P.S. I used the term "improperly filled" to describe the packing of David's scrubber. This is exactly the term that was used to describe it to me. It is a pejorative term and I would like to modify what it conveys.

Many CCR divers whose intention is to go "deep" (and I have never been close to the depths David achieved so deep in this case is anything between 60 and 120 metres), take greater than normal care when packing sofnolime into their scrubber canister. They will attempt to remove all dust and be anal about settling the lime as much as possible. I am in the school who believe that "really" tamping the scrubber so that you can get an extra few dozen grams into it, is counter-productive. What little benefit is derived from more media for CO2 to bond to is negated by an increase in Work of Breathing. This school of thought feels that even an extra joule per litre added to the WOB is potentially dangerous... let me rephrase that... challenging.

However, it is NOT uncommon for a CCR diver to cram a little more lime in for a deep dive. "We all do it," and I am sure that if David were here, he would be amply able to present very good reasons for the way he packed his that day.