Deep stops still in use in 2014?

[kwinter]

Run tables for a dive to 250 feet using VPM and GF 30/70. You won't see a huge difference in first stop depth. The debate is mostly academic.


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[dreamdive]

Just remember: you will ongas during a deep stop and during slow ascends! You figure out the rest.
If you happen to be at BTS this year. Attend AddHelium's lecture on Gradient Factors and decompression. It will answer this and more questions!

 

[Redshift]

Several people mentioned "recent studies". Could you please provide links or titles to such studies?

Yes, slow tissues may still be on-gassing during a deep stop, but their saturation levels may also be low while the fast tissues will be much more saturated and releasing more gas. And it's for those we are trying to avoid problems. DAN studies with different ascent profiles showed that those which included stops led to less bubble formation. They are not that old (2011) DAN | News Is there anything showing the opposite?

 

[Nasser]

Several people mentioned "recent studies". Could you please provide links or titles to such studies?

Yes, slow tissues may still be on-gassing during a deep stop, but their saturation levels may also be low while the fast tissues will be much more saturated and releasing more gas. And it's for those we are trying to avoid problems. DAN studies with different ascent profiles showed that those which included stops led to less bubble formation. They are not that old (2011) DAN | News Is there anything showing the opposite?

Here's a recent DAN lecture on Youtube that explains and discusses various deco models and some of the Navy's findings and test results. Of particular interest are the results regarding deep stops presented here starting at around 26:20


RF3.0- Decompression Methods - YouTube

 

[Redshift]

Here's a recent DAN lecture on Youtube that explains and discusses various deco models and some of the Navy's findings and test results. Of particular interest are the results regarding deep stops presented here starting at around 26:20


RF3.0- Decompression Methods - YouTube

Thanks, will take a look at it.

This is all very interesting. I remember a paper (I think it was available on Rubicon) that even showed dives with shorter total ascent time causing less bubbles...

 

[dreamdive]

Yes, because you load less. Slower ascents are not necessarily better.

 

[kwinter]

Yes, because you load less. Slower ascents are not necessarily better.

As you know, I'm not convinced on this part. Just because you may still be ongassing a little in slow compartments does not necessarily mean more likely to bubble. There may be other factors here. I wish Neal Pollack was going to be at BTS too, but you and Peter will have to do. See you Friday.


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[dreamdive]

As you know, I'm not convinced on this part. Just because you may still be ongassing a little in slow compartments does not necessarily mean more likely to bubble. There may be other factors here. I wish Neal Pollack was going to be at BTS too, but you and Peter will have to do. See you


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Looking forward seeing you there

 

[Nirvana]

Run tables for a dive to 250 feet using VPM and GF 30/70. You won't see a huge difference in first stop depth. The debate is mostly academic.


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I'm sorry, but the example given just shows that GF 30/70 is similar to VPM (at least using certain settings for VPM).

My take in the deep stops debate is that the issue is whether it would be better to set GF(Lo) closer to 20 or closer to 80, so to speak. VPM-B gives out profiles that approximates those offered by different GF(Lo/Hi) combinations. At least this is what I understood from what I've read, including some of the posts by Simon Mitchel and David Doolette on the Rebreather Forum thread mentioned before.

Fot my part, in my admittedly short 'career' doing technical dives, I've used VMP-B, usually in +4 conservatism.

 

[Ste Wart]

For a 50m dive I'd do 9mpm up to 80% of the Ata, then 6mpm to the first switch at 21m.

Not a really a deep stop, effectively the run time would be similar if I stopped there for a minute and then continued at 9mpm to 21m.

From an anecdotal point of view, I've been finding this method leaves me fresher after a dive as opposed to cutting a table using a deco program.

EDIT:

I shape the curve using Ratio Deco from 21m