Deep Stops Increases DCS

[PfcAJ]

You obviously haven't read the study. Tell me how padded a 30/70 profile is compared to the deep stops version run in this study.

Did you just say that Dr Mitchell hasn't read the study?

 

[tomfcrist]

i'm pretty sure Dr. Mitchell has read the study...

Did you just say that Dr Mitchell hasn't read the study?

Considering the text of the NEDU study directly contests his assertions....yup.. I said it.

 

[nadwidny]

Are deep stops effective if used properly? Absolutely, show me one piece of evidence to the contrary.

Well there is the study you're trying unsuccessfully to discount...

 

[PfcAJ]

Considering the text of the NEDU study directly contests his assertions....yup.. I said it.

Take a look at the man's CV. You're off the mark here.

 

[tomfcrist]

Well there is the study you're trying unsuccessfully to discount...

You obviously missed the part where I said "Properly" used...Vice this study, which decided to add 15 minutes or so to each deep stop. We all know that slow tissues are still ongassing at 80, 70 60 whatever feet....the idea is to slow the ascent enough to allow fast tissues a chance to offgas while limiting the amount that you ongas slow tissues. By staying at 70' for 12 minutes followed by 60' for 17, 50 for 15 and another 18 minutes at 40 feet, you are deliberately stacking the odds against the deep stop ideology. There is no possible outcome from this profile that would support starting deco earlier because they designed it that way.

---------- Post added December 22nd, 2014 at 11:52 AM ----------

Take a look at the man's CV. You're off the mark here.

AJ, Read what he wrote....I bolded it for you.

Sorry to be long winded, but my point is that for all you know the DCS rates for profiles in general technical diving might be very similar to those in the studies if the data were gathered in the same way, the case definitions were the same, and the profiles were genuinely dived to the letter with no padding or other strategies that might increase safety. There seems little basis for dismissing these studies merely because the reported rates of DCS are higher than you perceive is normal for technical diving.

What he is asserting is an oxymoron. The profiles in the study were NOT dived to the letter. They were ****ed with deliberately to increase the likelihood of a DCS event. All things are not created equal.

This is straight from the study...."Results indicate that slower tissue gas washout or continued gas uptake offsets the benefits ofreduced bubble growth at deep stops."

The study acknowledges that deep stops help reduce bubble growth, however under the parameters of this study the continued gas uptake offsets the benefit. Do you think that may be because they are doing a 174 minute total ascent from this dive?....that's over double the US Navy dive table, ZHL16....or whatever algorithm you want to throw at this dive. The results are valid, but the conclusion is based off of staying at the deep stops for damn near 20 minutes in some cases....Who is diving this profile? How often? Let me answer that for you....only the folks that were participating in this EXPERIMENT have ever willingly dove these EXPERIMENTAL profiles. Doolette has admitted that his job is to come up with off the wall **** and test it to see if it works.....in this case, neither profile worked very well.

I also find it interesting that up until 60 dives or so, the incidence of DCS was very much the same between the two profiles. In fact the first bent diver was diving the "shallow" first stop profile. The graph on page 8 shows the deep stops model maintaining a predictable incidence of DCS, while the Shallow model is very much inconsistent(3 bent divers very quickly, followed by 0 bent divers for the rest of the study).

Take it as you wish, but this study has very little to do with the type of diving 99.9% of tech divers are doing, and it applies to even less to Recreational "no stop" divers.

 

[PfcAJ]

in this case, neither profile worked very well.

And the deep stops one worked even worse than the shallow one.

The researches controlled for every variable they could control for, measured DCS rate in an objective manner, the ascent schedule was performed to the letter.

Dr Mitchell is right, you really DON'T know what the DCS rate is for a given profile, to include the ones you dive.

 

[tomfcrist]

That's funny, because niether do you by your logic.

 

[PfcAJ]

I don't know the rate. You're correct. I've never argued that I do.

 

[tomfcrist]

However I can assume you can do basic division...hell I bet there is a calculator laying around you can use.

Take 10 random dive buddys, and find out how many times they have been bent collectively. Divide that by their collective dive count(just deco).....I'll bet it's less than 3.4%...

 

[LiteHedded]

However I can assume you can do basic division...hell I bet there is a calculator laying around you can use.

Take 10 random dive buddys, and find out how many times they have been bent collectively. Divide that by their collective dive count(just deco).....I'll bet it's less than 3.4%...

you really have this science thing down and a firm grasp on the ins and outs of the NEDU study. I can't understand why Dr. Doolette hasn't stopped by to debate this issue with you.
he really should've consulted with you when he designed his study.