Is DCS possible under 20fsw, or 100% impossible?

[Nitrox_DiverNY]

ScubaBoard is very lucky to have a noted and very prominent DCS research doctor (amongst many here). You might want to ask for links to some of his recommended articles he's written to explain the basics of how DCS works. He's @Dr Simon Mitchell

Thank you I will send him a PM for the links, safe diving!

 

[Nitrox_DiverNY]

Hi @Will_

Your question got me interested. First I looked up the NDLs on the DSAT and PZ+ tables. The tables start at 30 feet. On air, the NDLs are 4:20 for DSAT and 3:17 for PZ+

So, I went to MultiDeco. I could not find a deco dive at even 24 hours until I lowered the GF high to 60, then you get a whopping 7 min of deco. So the practical answer to your question is no to being able to exceed the NDL. Does not answer the question about being able to have an episode of DCS, but that is likely no also. I don't know about you, but I could only make a little under 2 hours at 20 feet with an AL80

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very cool, thanks for input, including that dive plan! safe diving!

 

[Nitrox_DiverNY]

We just finished a mammoth thread nearly the same topic. It finally came to an end with research on shallow saturation divers. It was found that shallower then 20 feet, a saturated diver could go directly to the surface. Deeper than 20 feet, the potential for DCS started to rise sharply. That means that, yes, you can dive shallower than 20 feet for as long as you wish.

very interesting, Ill try to look that thread up. so theoretically one could "live" at 20ft in one of those underwater research domes and ascend to the surface without any incidence of DCS

 

[Wibble]

very interesting, Ill try to look that thread up. so theoretically one could "live" at 20ft in one of those underwater research domes and ascend to the surface without any incidence of DCS

No.

You would be diving beyond Non-Deco Limits and be fully saturated, i.e. Saturation Diving. You would probably need to decompress from 20'/6m.

 

[Nitrox_DiverNY]

Most DCs I've seen don't even start computing No Deco time until they get below 30 feet deep. As others have stated, you would need to intentionally have to stay at 20 feet for an extremely long time before getting a DCS hit. And we're talking many, many tanks of air for quite a number of hours.

thanks for the input! and yes lots and lots and lots of AL80s....haha

 

[Nitrox_DiverNY]

Nitrox for shallow water artifact diving??

This is the study from which the quote was taken: https://www.researchgate.net/public...n_humans_DCS_risk_and_evidence_of_a_threshold

nice ill check it out, thanks!

 

[Nitrox_DiverNY]

DCS - Decompression Sickness. Does this include burst lung (as it was in old money), or are we just talking about 'bends'?

Rapidly bolting to the surface from 20'/6m is pretty dangerous even though the likelihood of a "bend" through absorbed gases coming out of solution is highly unlikely (if within no-deco limits).

just DCS, and I agree bolting to the surface is likely unsafe still at 20fsw

 

[Nitrox_DiverNY]

He was a good documentarian: red corals AND OVER 210 BAR!

nice ill check that out

 

[Nitrox_DiverNY]

In normal scuba-speak:

DCS (the topic of this thread) refers specifically to decompression sickness and is commonly called the bends.
DCI (not the topic of this thread) refers to Decompression illness, and is used to refer to both DCS and lung barotrauma, primarily because of the problem of distinguishing the symptoms of the two.

thanks!

 

[Nitrox_DiverNY]

Exactly

Decompression illness (DCI) = Decompression sickness (DCS) + Arterial gas embolism (AGE)

Decompression illness results from a reduction in the ambient pressure surrounding a person’s body. It is commonly caused by pressure changes that occur in scuba diving, a very popular sport in many parts of the world. Decompression illness includes two conditions: decompression sickness and arterial gas embolism. Decompression sickness is thought to result from bubbles growing in the tissue and causing local damage. Arterial gas embolism results from bubbles entering the circulation, collecting together and travelling through the arteries and causing tissue damage by blocking blood flow to the small vessels.

nice thanks for making it more understandable to a new diver!