Time at Deepstop

I read an article today, saying that the 'newest' research shows that a short (1 min) deepstop (at half max depth) actually increases bubble formation, whereas the optimal of 2,5 min deepstop virtually eliminates level 3-4 bubbles. However, the computers (mine & others) normally stipulates a deepstop of 1 min? (sorry if been covered in a thread and didn't find).

Do you have a link to the article? Maybe I am misunderstanding, but if bubble formation is increasing during a minute stop, what would change if it were extended to 2.5 minutes? I would think that would just be one and a half extra minutes of bubble formation. Ignoring saturation, bubble formation is a function of depth, not time.

My guess is they are saying 1 minute deep stop shows increased bubble formation on the surface compared to the 2.5 minute deep stop. I too would like to see the article (although I've seen the 2.5 minutes mentioned elsewhere, so it may be an older article)

But bubble formation is also a function of time. Spending more time at shallower gradients (deeper depths) will allow decompression of the fast tissues before the bubbles are formed, while slow tissues are still being loaded. So the questions is what depth and for how long is most beneficial.

The Maroni study just moved 1 mins from the typical 3min 15ft safety stop down to deeper depths and left the remaining 2 mins at 15ft.

The longer stops worked better because they were, duh longer! Given the chance, lengthening your overall ascent time into a roughly asymptotic shape is the best way to reduce post dive bubbling - based on the principle that every dive is a deco dive to some extent. So from an 80ft, 30 min, air dive you might do a 5 to 8 min ascent with (e.g.) 1 min at 40ft, 2 @ 30ft, 2 @ 20ft, and 3 @ 10ft.

Go by how you feel afterwards. Achy, tired, falling asleep on the boat, try lengthing the ascent time. Just don't overstay too long at the deeper depths.

albertvw:

I read an article today, saying that the 'newest' research shows that a short (1 min) deepstop (at half max depth) actually increases bubble formation, whereas the optimal of 2,5 min deepstop virtually eliminates level 3-4 bubbles. However, the computers (mine & others) normally stipulates a deepstop of 1 min? (sorry if been covered in a thread and didn't find).

Click to expand...

When you describe an article in a thread, it helps if you identify the article, or the author, and provide a citation and link to the article in the thread.

Believe it or not, there are numerous articles out there, and not all of them are by reputable or peer-reviewed researchers.

Not only that, but many studies are "N of 1" studies, or low-N studies, where the results may be valid as far as they go, but they don't go very far because they cannot be generalized to a broader population.

Moreover, to be able to compare findings, you'd need to be able to discuss methodology - how the bubbles were measured afterwards, etc., and definitions of terms.

Lots of different variables plausibly impact the formation of bubbles - it would be difficult to isolate variables to the point that a researcher could definitively state that "a difference of 1 minute" at a specified depth CAUSED a specific outcome e.g. "more bubbles". It is difficult to consistently and repetitively "hold all other variables equal" to do that, unless you're in a laboratory environment...which is possible. I also would like to know which article you are referring to.

Best,

Doc

I believe this is the paper that was referenced. Note the disclaimer.
Rubicon Research Repository: Item 123456789/7901

cwkline:

I believe this is the paper that was referenced. Note the disclaimer.
Rubicon Research Repository: Item 123456789/7901

Click to expand...

Thank you, cwkline.

I appreciate your effort.

This paper illustrates one of the items I mentioned above - 'definition of terms' - they are defining a 'deep stop' as, respectively, 50 fsw and 82 fsw.

Let me look around and see if I can find the original Richard Pyle article simply to compare his dive parameters.

Edit:

Yup, here it is:
http://www.bishopmuseum.org/research/treks/palautz97/deepstops.html

Note how Pyle defines 'deep stops' as a variable, dependent on both the curve and his deepest depth, but for the purposes of basic description he's talking about 125 fsw on a relatively consistent basis.

While neither article links conclusions to a broader population (pertaining specifically to mixed gas diving), the point is that when comparing one research paper to another it is helpful to first ascertain that you're not comparing apples to oranges.

Thanks again to cwkline for the citation, and to albertvw for bringing the topic up!

Regards,

Doc

Whats important to note, I think, is that paper used 82' as its bottom depth which is well within recreational limits. also the first stop depth was at 50' which is less than half way to the surface. IMO deep stops have to be tailored to the depth, sometimes 80% max and sometimes 50% max or whatever. There are to many variables for such a short paper to provide good reference. Of course if you dive to 82' every time then maybe its useful, otherwise you need to be well informed and tailor deep stops to your comfort level IMHO.

My guess is that the article albertvw read was a write-up in the latest edition of Submerge Magazine). Verna van Schaik writes an interesting and somewhat technical article on preventing bubbles. She doesn't mention what specific article or research this conclusion is drawn from but here is what she wrote, and note the last point she makes:

The research on which the new extended deep stop is based re-affirms the original 2:1 ratio theory. It indicates that a 2.5 minute deep stop (for their 25m dive) often completely eliminated type 3 and 4 bubbles - bubbles were graded as follows: 0 (none), 0.5 (sporadic), 1(15 bubbles over one minute with bubble showers), 2 (30 bubbles), 2.5 (>30 bubbles with showers), 3 (virtually continuous bubbling), 3.5 (continuous bubbling) and 4 (continuous bubbling with continuous showers). They had some other interesting findings.
Finding one - After a 2.5 min deep stop, decreasing the shallow stop time from five minutes to one minute made no significant difference to bubbling. [more text omitted]
Finding two - Without a deep stop, increasing the shallow stop time did not give you the same effect as a profile with a deep stop. [more text omitted]
Finding three - If a deep stop is used and you stay for less than 2.5 minutes you ACTUALLY INCREASE YOUR BUBBLING as compared to not having the deep stop at all. So basically either do not do the deep stop or do it properly spending at least 2.5 minutes, otherwise you are making it worse.

Click to expand...

That (Submerge Mag) is where I read the article as quoted by Deefstes. So the simple confusion: Article shows 'error' of 1 min deepstop vs computers which advise 1 min deepstops?