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Thread: Mk VI fatality-Canada

  1. #81
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    Re: Mk VI fatality-Canada

    Quote Originally Posted by Nitrogenius;438586


    [I
    Interesting that coming from you Mark.. Didn't you in another thread in another world argue that diving a rebreather was safer in cave environment.. Whay would that not be the case in open water then?
    Could one not get entangled in open water in e.g. fishing lines and then use the extra commody of plenty of gas supply?
    That was the side of the argument I had raised earlier as one side of Rebreather diving being safer then OC also in "Rec conditions"..
    I am not saying that I am agreeing with the marketing that it is essentially safer in an overall perspective, but there is leeway for argumentation that it can be safer being fair enough and not deceptive and fraudulent in a marketing context..
    That's all I am saying [/I]
    Marketing will always accentuate a products advantages over its disadvantages as that is its job after all, to sell the product!! But the difference here with this specific product is that in the relatively short life span of this product a number of people - I believe 6 at the last count - who purchased this rebreather are now dead.

    That's all I am saying

    cathal

  2. #82
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    Re: Mk VI fatality-Canada

    Quote Originally Posted by Nitrogenius  View Original Post
    Fair enough.. I am also not evry happy about the rec CCR approach in general and coming along with it a training by solely profit driven organisations like PAID etc.. That is from the issues and forthcoming restrictions, limitations etc. that will follow the route of future potential bad training as it has in OC rec that proficiantly trained and responsable divers then still will have to adhere to as dive operations will not be willing to tell the difference or at least only few will..
    But that is a different story.. I just don't get the rant on the marketing, beacuse marketing stays what it is marketing and as such is always full of a tiny bit of BS..

    What I forgot to adress earlier though was:



    Interesting that coming from you Mark.. Didn't you in another thread in another world argue that diving a rebreather was safer in cave environment.. Whay would that not be the case in open water then?Could one not get entangled in open water in e.g. fishing lines and then use the extra commody of plenty of gas supply?
    That was the side of the argument I had raised earlier as one side of Rebreather diving being safer then OC also in "Rec conditions"..
    I am not saying that I am agreeing with the marketing that it is essentially safer in an overall perspective, but there is leeway for argumentation that it can be safer being fair enough and not deceptive and fraudulent in a marketing context..
    That's all I am saying
    OW recreational depth diving with limited or no restriction on direct ascent to the surface is best served by OC and a redundant pony tank

    Cave is probably the most dangerous environment for a diver. Deco is an OHE but ultimately you can take the bend option and go for the surface but in a cave your just totally screwed.

    Same is true for wreck penetration dives so I guess a long wreck penetration dive in shallow water would count but i don't know many of those.

    I dont believe CCR is as dangerous as people make out. For me its about the same risk balance as a twin set and two deco stages on multi gas decompression dives.


    Hope that makes my position clear.

    ATB

    Mark

  3. #83
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    Re: Mk VI fatality-Canada

    Quote Originally Posted by cb1  View Original Post
    Marketing will always accentuate a products advantages over its disadvantages as that is its job after all, to sell the product!! But the difference here with this specific product is that in the relatively short life span of this product a number of people - I believe 6 at the last count - who purchased this rebreather are now dead.

    That's all I am saying

    cathal
    And these sad tragedies are related to the marketing??
    Is that what you are stating?

    Please have a look at the causes.. I belive non of them are related to the unit as such.. At least a lot is caused by massive breaches of protocolls..

  4. #84
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    Re: Mk VI fatality-Canada

    "I am not saying that I am agreeing with the marketing that it is essentially safer in an overall perspective, but there is leeway for argumentation that it can be safer being fair enough and not deceptive and fraudulent in a marketing context..
    That's all I am sayin
    g"

    I referred to the fatality statistics for this unit because of your statement where you say you are not agreeing that the unit is essentially safe, but then claim there is leeway that this unit can be safer than O.C without the marketing being deceptive??

    regards

    Cathal

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    Re: Mk VI fatality-Canada

    Quote Originally Posted by cb1  View Original Post
    "I am not saying that I am agreeing with the marketing that it is essentially safer in an overall perspective, but there is leeway for argumentation that it can be safer being fair enough and not deceptive and fraudulent in a marketing context..
    That's all I am saying"

    I referred to the fatality statistics for this unit because of your statement where you say you are not agreeing that the unit is essentially safe, but then claim there is leeway that this unit can be safer than O.C without the marketing being deceptive??

    regards

    Cathal
    You are twisting my words there and take them out of context from what I had stated earlier..
    There is leeway for argumentation to support such statment and therefore adress it very positively from a marketing stance.
    This is "completely normal" marketing and thus not especially deceptive as claimed to be by Jont..
    That is my point and nothing else, so I am sick of this senseless bickering on these marketing slogans..
    The unit is what it is and of course not what marketing says about it, because no product is in any marketing!
    Get real and use common sense, that's what I am saying..

    The incidents are tragic. The incidents appear to be a lot, but as long as we do not know how many units and how many dives that remains a very subjective impression as with all other rebreather accidents..
    But in no way are these in any way linked to the marketing..
    So just take the marketing as marketing and the unit as unit and rec CCR as rec CCR these are all different pairs of shoes..

  6. #86
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    Re: Mk VI fatality-Canada

    Quote Originally Posted by cb1  View Original Post
    Marketing will always accentuate a products advantages over its disadvantages as that is its job after all, to sell the product!! But the difference here with this specific product is that in the relatively short life span of this product a number of people - I believe 6 at the last count - who purchased this rebreather are now dead.

    That's all I am saying

    cathal

    Trying not to be disrespectful to those who has perished here... but...In terms of safety, no accident was caused by the unit. To my knowledge, where facts has been presented, was diver related accidents.

    No real facts has been presented here, but previous accidents has indicated wrong mindset, stress, unexperience, lack of understanding basic training?

    Training is there, training is solid, training will teach you how to deal with the unit, Regardless of marketing BS. Now if this is, by any reason what so ever, disregarded.... then what? We blame the unit for being unsafe?

    Really?

    I am not saying it is safe - neither is OC....

  7. #87
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    Re: Mk VI fatality-Canada

    Quote Originally Posted by Mark Chase  View Original Post

    By the by i am still baffled at how you can validate a cell on the co? cells take time to settle and multiple flushes are required to ensure the correct calibration / check gas. If they have pulled it off then great but i am still unconvinced as to just how it checks cells mid dive without significantly altering loop PP02?

    Does it have a mini chamber around the cells it isolates from the rest of the loop & flushes? If so what if the mini chamber jams shut and all you see is the PP02 in that and not on the whole loop?

    Id be very interested if someone could explain it in detail.
    I will try and get time to do a tear-down of the MkVI with some explanations around the functionality, to the best of my knowledge.

    But to quickly respond to your questions;

    The primary cell is validated continuously during the dive, it plots a reference curve. It also do the same with the secondary cell. So now the unit has a curve on how the two cell corresponds to each other. The cell value is read at an exact moment (based on temperature and temperature compensation). This has been somewhat cumbersome in the past where the reading of the cell value was not as expected due to failures in the temperature/compensation. This has lead to C1-errors (failed validation). The cells resides in a small chamber with a restriction to the breathing loop that are the size of a normal pinky finger in diameter. The gas is not injected directly onto the cell membrane, it is bouncing of the chamber wall, in a 45 degree angle. Validation does not require more gas than a couple of cc, and not altering the loop pO2 noticeable. The chamber is open, so there are no risk of a jam.

    Now, you can all have opinion of this design and you might even call it flawed. But then again, you might want to consider who is the chief engineer behind the MkVI and say to yourself.... "I have superior knowledge"

  8. #88
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    Re: Mk VI fatality-Canada

    Quote Originally Posted by Jeppe_E  View Original Post
    In terms of safety, no accident was caused by the unit.
    It doesn't matter from a statistical point of view.
    Was he wearing a rebreather when he died? Then mark it as a rebreather fatality.
    Was he wearing a MKVI when he died? Then mark it as a MKVI fatality.

    Doing anything other than that is an insult to math/statistics/science.

  9. #89
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    Re: Mk VI fatality-Canada

    Quote Originally Posted by Steve Schultz  View Original Post
    It doesn't matter from a statistical point of view.
    Was he wearing a rebreather when he died? Then mark it as a rebreather fatality.
    Was he wearing a MKVI when he died? Then mark it as a MKVI fatality.

    Doing anything other than that is an insult to math/statistics/science.

    As we all know, there are three kinds of lies...

    A white lie
    A damned lie
    Statistics

    And this discussions has nothing to do with statistics, more than it is a number. For it to be statistically relevant we need to have something to measure it against... Hell, lets run it through Minitab and do a standard deviation chart.. It will most probably tag these 6 incidents as outliers, thereby stating that the unit is "safe"

  10. #90
    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: Mk VI fatality-Canada

    Quote Originally Posted by Jeppe_E  View Original Post
    I will try and get time to do a tear-down of the MkVI with some explanations around the functionality, to the best of my knowledge.

    But to quickly respond to your questions;

    The primary cell is validated continuously during the dive, it plots a reference curve. It also do the same with the secondary cell. So now the unit has a curve on how the two cell corresponds to each other. The cell value is read at an exact moment (based on temperature and temperature compensation). This has been somewhat cumbersome in the past where the reading of the cell value was not as expected due to failures in the temperature/compensation. This has lead to C1-errors (failed validation). The cells resides in a small chamber with a restriction to the breathing loop that are the size of a normal pinky finger in diameter. The gas is not injected directly onto the cell membrane, it is bouncing of the chamber wall, in a 45 degree angle. Validation does not require more gas than a couple of cc, and not altering the loop pO2 noticeable. The chamber is open, so there are no risk of a jam.

    Now, you can all have opinion of this design and you might even call it flawed. But then again, you might want to consider who is the chief engineer behind the MkVI and say to yourself.... "I have superior knowledge"
    Thanks for taking the time to explain. It dosn't answer all my questions but it gives me a far better picture.

    ATB

    Mark

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