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Thread: Fascinating lecture on Decompression by Dr. Simon Mitchell

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    RBW Member Tekkie is an unknown quantity at this point Tekkie's Avatar
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    Re: Fascinating lecture on Decompression by Dr. Simon Mitchell

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    Cool Re: Fascinating lecture on Decompression by Dr. Simon Mitchell

    Quote Originally Posted by decostanza  View Original Post
    Thank you Dr. Mitchell for sharing this fascinating and very thought provoking information!
    Don
    yes i agree ,it's very very instructif ,a Book as that cannot end in a wheelbarrow :)


    Franc

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    Re: Fascinating lecture on Decompression by Dr. Simon Mitchell

    Quote Originally Posted by Tekkie  View Original Post
    Page not found...
    Hi Tekkie, here is the youtube link (to what I believe is the lecture):
    https://www.youtube.com/watch?v=UY61E49lyos

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    Re: Fascinating lecture on Decompression by Dr. Simon Mitchell

    Quote Originally Posted by shaggy  View Original Post
    Hi Tekkie, here is the youtube link (to what I believe is the lecture):
    https://www.youtube.com/watch?v=UY61E49lyos

    caveat emptor...

    Then take a read of this, or this, and see what happened to this diver, when he followed Dr. Simon Mitchell's new advice. The truth is, in some dives the deeper stops are essential.

    Pioneer divers 20+ years ago, learned these lessons the hard way, and corrected for them with deeper stops, which led to the models we use today.

    The theoretical improvements Simon claims in that video, do not translate to actual benefits. I could list a dozen invalid interpretations and false assumptions that are used or shown in his youtube presentation. But we have done that argument numerous times.

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    Re: Fascinating lecture on Decompression by Dr. Simon Mitchell

    Roosh, you need to make sure to differentate between deep stops (as defined as half way from the bottom to your first deco stop) and deeper initial deco stop.

    Even though you are using my DCS hit as an example, I still do not think deep stops are valid or even needed for that matter. A deeper inital deco stop could have been a valid Argument though and I will be implementing that.

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  6. #26
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    Re: Fascinating lecture on Decompression by Dr. Simon Mitchell

    Quote Originally Posted by rossh  View Original Post
    caveat emptor...

    Then take a read of this, or this, and see what happened to this diver, when he followed Dr. Simon Mitchell's new advice. The truth is, in some dives the deeper stops are essential.

    Pioneer divers 20+ years ago, learned these lessons the hard way, and corrected for them with deeper stops, which led to the models we use today.

    The theoretical improvements Simon claims in that video, do not translate to actual benefits. I could list a dozen invalid interpretations and false assumptions that are used or shown in his youtube presentation. But we have done that argument numerous times.

    .

    I still can not see how you manage to use that incident as proofing your arguments.
    There are many factors and a lot of what Don had described was not optimal. So one must not jump top the conclusion that the hit was related to the relatively shallow first stop.
    I had already mentioned it in the other forum what much more likely was (also!) a contributing factor was the fast ascent rate until first stop (exceeded all recommendations that exist completely independently from which model used for choosing the decompression approach by a factor of 2), not optimal choice of gas, tracking of PO2, physical excertion, temperature etc. etc.


    You make yourself less and less credible with the way you are acting ross.. While in the argument about the NEDU study you had been insisting that the fact of temperature was not properly reflected now you try to ignore other factors that can easily contribute to a hit and try to point it towards one single issue.
    You now contradict yourself. You really try to push your agenda by any means necessary..



    As for the statement look what happened, following Simons advice..
    Did Simon advice to dive a GF 60/90 whith hi content He mix and an ascent rate of 60'/min until first stop??
    Most certainly not! In fact he always said that folks should be very careful in going shallower with the first stop and said there was indication that it might be beneficial and deepstops or starting shallower might have less beneficial aspect than prior NEDU study anticipated..


    So stay real!

  7. #27
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    Re: Fascinating lecture on Decompression by Dr. Simon Mitchell

    Hit sent to early: To be fair.. sure the relatively shallow stop might have very well contributed to the hit, but that does not mean that starting extremely deep is better and also not clear at all if the hit would not have happened as well due to the other factors..

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    Re: Fascinating lecture on Decompression by Dr. Simon Mitchell

    Quote Originally Posted by rossh  View Original Post
    caveat emptor...
    Indeed.

    Quote Originally Posted by rossh  View Original Post
    Then take a read of this, or this, and see what happened to this diver, when he followed Dr. Simon Mitchell's new advice.
    Looking at a single data point as proof of anything is just kicking both science and statistics squarely in the nuts.

    This deep stop vs shallow stop discussion is starting to reek of the fanboyisms you see in Windows vs Mac vs Linux discussions and the like.

    I think everyone benefits from keeping an open mind about deep vs shallow stops. People aren't dropping like flies because they choose one method over the other. I have done my fair share of diving using both. I'm of the mindset that there are many more factors than just the planned profile that determine outcome.
    Eg:
    Was the planned profile followed precisely or was there yo-yo-ing?
    Was there lots of exertion due to current?
    Cold?
    Injured/sore joints and muscles from workouts?
    etc

    Looking at a single data point (DSix's dive) and drawing conclusions that he would have a better outcome by following deep stop profile is impossible to predict without some kind of sorcery or crystal ball.

  9. #29
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    Re: Fascinating lecture on Decompression by Dr. Simon Mitchell

    Quote Originally Posted by Steve Schultz  View Original Post
    I'm of the mindset that there are many more factors than just the planned profile that determine outcome.
    ...
    Looking at a single data point (DSix's dive) and drawing conclusions that he would have a better outcome by following deep stop profile is impossible to predict without some kind of sorcery or crystal ball.
    Well said :)

  10. #30
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    Re: Fascinating lecture on Decompression by Dr. Simon Mitchell

    Quote Originally Posted by Nitrogenius  View Original Post
    I still can not see how you manage to use that incident as proofing your arguments.
    There are many factors and a lot of what Don had described was not optimal. So one must not jump top the conclusion that the hit was related to the relatively shallow first stop.
    I had already mentioned it in the other forum what much more likely was (also!) a contributing factor was the fast ascent rate until first stop (exceeded all recommendations that exist completely independently from which model used for choosing the decompression approach by a factor of 2), not optimal choice of gas, tracking of PO2, physical excertion, temperature etc. etc.


    You make yourself less and less credible with the way you are acting ross.. While in the argument about the NEDU study you had been insisting that the fact of temperature was not properly reflected now you try to ignore other factors that can easily contribute to a hit and try to point it towards one single issue.
    You now contradict yourself. You really try to push your agenda by any means necessary..



    As for the statement look what happened, following Simons advice..
    Did Simon advice to dive a GF 60/90 whith hi content He mix and an ascent rate of 60'/min until first stop??
    Most certainly not! In fact he always said that folks should be very careful in going shallower with the first stop and said there was indication that it might be beneficial and deepstops or starting shallower might have less beneficial aspect than prior NEDU study anticipated..


    So stay real!
    Stay real??

    His actual profile was a 60/70.... (because of the inbuilt way his computer rounds up longer). i.e. exactly following the newer "more efficient" (??) planning method recommended by Dr. Simon Mitchell.

    The go slower theory was addressed in the other thread - it would have made for 13 continuous minutes of elevated supersaturation and uninterrupted tissue bubble growth - double the time - that's not an improvement.

    Remember this diver had a DCS develop in the water, in the ascent. The contributing factors are rather limited.

    This discussion is now spread other three threads here here, here. The suggested alternate theories have been discussed / shown to be n/a, in my opinion.

    Fast tissues do matter, deeper stop are beneficial, and essential in some cases.

    This injury and method is not new - pioneer divers learned this lesson before. It seems the new experts have forgotten or don't know about the past, so they / we are destined to repeat it.

    Unfortunately there will be more (avoidable) Don Six type incidents to come....


    ****

    Steve, his actual dive profile is in the other thread.
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