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Thread: Deep stops debate (split from ascent rate thread)

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    Deep stops debate (split from ascent rate thread)

    You can say what you want about deep stops and VPM vs Buhlman. Nothing is conclusive. But knowing that I have a small PFO means I am going to take a more conservative ascent rate and not fly up to the shallows, even in the presence of CO2 if I can control it.
    Ken

    Quote Originally Posted by Dsix36  View Original Post
    Just remember that listening to an idiot such as myself may very well get your arse dead.

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    Re: Controlling Ascent rates

    Quote Originally Posted by kwinter  View Original Post
    You can say what you want about deep stops and VPM vs Buhlman. Nothing is conclusive. But knowing that I have a small PFO means I am going to take a more conservative ascent rate and not fly up to the shallows, even in the presence of CO2 if I can control it.
    But thats just the point

    You think your being conservitive by doing deep stops and slow ascents but didnt the test data show you were actualy doing the exact opposit and exposing your self to far greater risk of a bend?

    Persoanly i dont do 9m/min purely because I cant do it safely. I like slow progressive ascents because i feel more in control, so I put up with the resulting greatly increased shalow stops.

    Bhulman did most of the proper testing and he came up with errr Bhulman Profiles and all the recent proper testing apeares to support the concept of getting shalow faster and staying there longer.

    To the best of my knowladge there is no proper manned test data to support deep stops. If there is id like to know about it. Best i have found is anacdotal stuff by R. Pyle

    ATB

    Mark

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    Re: Controlling Ascent rates

    Mark

    Who do you know using buhlmann? Everyone I know is using GF or VPm, which keep you deep waaaaay longer than buhlmann
    Andrew Ainslie

    Buhlmann = Bend and Mend
    VPM/RGBM = Mend and Bend
    GF 35-50/70-85 = Mend and Mend

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    Re: Controlling Ascent rates

    Back to US navy A soon are we? . Dude , GF is just a padded Bhulman.

    Temperature is a factor most forget and in OW cold water we usually have warmer water on the shallow stops. Extending stops in the cold deep part of the deco might not be efficient. Plan your deco according to the environment you are in might be wise.

  5. #5
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    Re: Controlling Ascent rates

    Quote Originally Posted by aainslie  View Original Post
    Mark

    Who do you know using buhlmann? Everyone I know is using GF or VPm, which keep you deep waaaaay longer than buhlmann
    Yes. Exactly right. No one has used real Buhlmann in any correct amounts - ever. Not in the last 12 years anyway.

    Divers do what comes naturally - about an ascent rate of 5 to 7m/min. That translates into more time deeper for all models.

    Regards
    Last edited by rossh; 24th August 2013 at 00:09.
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    Re: Controlling Ascent rates

    Quote Originally Posted by Mark Chase  View Original Post
    To the best of my knowladge there is no proper manned test data to support deep stops. If there is id like to know about it. Best i have found is anacdotal stuff by R. Pyle

    ATB

    Mark
    Take a look at the 2008 UHMS Deco and Deep workshop report.

    There are test reports supporting deep stop success. There was an even split of data going both ways. In fact the consensus position was neutral, and not conclusive.

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  7. #7
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    Re: Controlling Ascent rates

    Quote Originally Posted by rossh  View Original Post
    Take a look at the 2008 UHMS Deco and Deep workshop report.

    There are test reports supporting deep stop success. There was an even split of data going both ways. In fact the consensus position was neutral, and not conclusive.

    Regards

    Yes i have looked at this report and as you correctly say in a comparison between Bhullman and Deep stop profiles the results were neutral.

    IE no evidence to support deep stops as better or worse than Bhulman

    However looking at the profiles you put up in response to discussion on this before its apparent the deep stop profile in VPM format required extended shallow stops to make up for the increased saturation incurred by the deep stops??

    Which taken on face value seems daft

    There was a great deal of discussion on this here

    "re-assessing deco profiles and deep stops", plus other bits.. - Page 10 - CCR Explorers


    What is apparent is the once popular very deep stops are now out of fashion. When I first looked at ratio deco a la GUE I commented the deep stops were apparently below the M value for off gassing. I supported your view that the fist deep stop shouldn't be 80% ATA but not less than 2ATM above max depth to avoid on gassing with no theoretical off gassing benefit (assuming M values give reasonable base line for off gassing)

    Whilst theres no doubt most tec divers are still doing GF or VPM stile deep stops, there is wide spread acceptance that the old GI3 theory of " get the deep stops right and you can forget the shallow stops" and concepts like "taking half the shallow stop time and spread it across the deep stops" have been consigned to the waste basket of half arsed ideas.

    If we do deep stops we accept we are on gassing some tissue compartments that will then require extended shallow stops to clear safely. So deep stops = extended decompression for the overall profile.

    ATB

    Mark

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    Re: Controlling Ascent rates

    Quote Originally Posted by aainslie  View Original Post
    Mark

    Who do you know using buhlmann? Everyone I know is using GF or VPm, which keep you deep waaaaay longer than buhlmann

    I agree but I have noticed a distinct shift away from very deep stops in the last few years and big questions being raised by those who follow the latest information on deco.

    I was running 10/90 GF for years but I have taken on board current thinking and moved to 35/90 to eliminate very deep stops and accelerate the rest.

    So far nothing to report apart from shorter overall deco

    Personally I didn't get bent on 10/90 and touch wood i haven't been bent on 35/90

    I was first alerted to this when the Britannic expedition decided to run VPM deep profiles with extended shallow Bhulman type stops. It raised the question in my mind and it hasn't gone away.

    ATB

    Mark
    Last edited by Mark Chase; 24th August 2013 at 05:30.

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    Re: Controlling Ascent rates

    Hi Mark, from comparing profiles, you will notice VPM-B profiles are more similar to 3O/85 protiles than 10/90.
    You need to remember straight Buhlman profiles are 100/100 and only with use of GF low deep stopps are generated. VPM-B does this out of the box. What some are doing lately with GF low arround 30 instead of smaller number is even more similar to VPM-B profiles.
    And I agree profiles with 10/90 GF have been for me always a bit unrealistic because of all 1 min stops that were inserted for me at depth where they were quite inefective. VPM does this for me better. And there was always known you must do all stops VPM generates.

    So all this days diving (VPM and GF profiles) is diving deep stop profiles.
    Only straight Buhlman is shallow stop decompression strategies diving...


    Sent from my PAP4500DUO using Tapatalk 2
    Last edited by Igor P; 24th August 2013 at 09:08.

  10. #10
    So many CCR So little etc Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase's Avatar
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    Re: Controlling Ascent rates

    Quote Originally Posted by Igor P  View Original Post
    Hi Mark, from comparing profiles, you will notice VPM-B profiles are more similar to 3O/85 protiles than 10/90.
    You need to remember straight Buhlman profiles are 100/100 and only with use of GF low deep stopps are generated. VPM-B does this out of the box. What some are doing lately with GF low arround 30 instead of smaller number is even more similar to VPM-B profiles.
    And I agree profiles with 10/90 GF have been for me always a bit unrealistic because of all 1 min stops that were inserted for me at depth where they were quite inefective. VPM does this for me better. And there was always known you must do all stops VPM generates.

    So all this days diving (VPM and GF profiles) is diving deep stop profiles.
    Only straight Buhlman is shallow stop decompression strategies diving...


    Sent from my PAP4500DUO using Tapatalk 2
    Sure but do you remember when we were all being told to take the baseline of 35/85GF and then to "smooth the curve" by redistributing the shallow stops on to the deeper ones and then adding deep stops down to 8-0% ATA?

    Thats the bit thats gone out of fashion

    I have looked at VPM as it was supposed to handle He better than Bhulman and then tried to mimic it with GFs because my Hammer Head, X1 or Sheerwater was running GF's Personally i found the profiles to be a little more aggressive on the shallow stops than 85 GF? Running VPMB2 I found them a lot more aggressive (typical dive would be CCR1.3 15/65Mix 45mins at 65-70m)

    I ended up running VPMB level 4 to get the shallow stops more in line with my requirements of 90GF

    Theres nothing wrong with that and i don't have anything against VPMB apart from the fact i don't know how to manipulate it on a dive if I need to blow off deep stops to conserve gas.

    I personally have stuck a toe in the water with 35/90GF in so far as i am not willing to abandon deep stops all together but I am very open minded to the prospect of cutting back on them possibly a lot further than 35GF

    I await far more intelligent people than me to do the necessary testing before i go further but the most up to date stuff seems to be leaning that way.

    ATB

    Mark

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