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Thread: Raid

  1. #41
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    Re: Raid

    Quote Originally Posted by Steve Schultz  View Original Post

    Dumbing down rebreather training for the average diver is not a good idea.
    A thorough training course and lots of experience is what will save a diver when problems arise.

    I have never dumbed down the training. one must rely that the training material and the certified instructors is sufficient to train divers on these machines. But people here seems very reluctant to even try to look over the horizon of their own world. I totally agree that thorough training and loads of experience will save a diver.

  2. #42
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    Re: Raid

    Quote Originally Posted by Jeppe_E  View Original Post
    I have never dumbed down the training. one must rely that the training material and the certified instructors is sufficient to train divers on these machines. But people here seems very reluctant to even try to look over the horizon of their own world. I totally agree that thorough training and loads of experience will save a diver.
    Sorry, didn't mean to imply that you or any specific instructor isn't teaching the material well or within standards. I was referring to the actual course material. From what I can see, RAID takes someone with considerably less experience than the other agencies require and teaches them less theory and practical skills than the other agencies do. That sets off warning bells.

    I guess what I'm saying is that just because the operation of a specific rebreather is very simple, I don't think that the training should learn less or that the diver prerequisites be any less than for more involved rebreathers.

  3. #43
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    Re: Raid

    Quote Originally Posted by Steve Schultz  View Original Post
    Sorry, didn't mean to imply that you or any specific instructor isn't teaching the material well or within standards. I was referring to the actual course material. From what I can see, RAID takes someone with considerably less experience than the other agencies require and teaches them less theory and practical skills than the other agencies do. That sets off warning bells.

    I guess what I'm saying is that just because the operation of a specific rebreather is very simple, I don't think that the training should learn less or that the diver prerequisites be any less than for more involved rebreathers.

    Yes, I agree, and I cannot say about the RAID Course, since I am doing it under PADI. Problem here is that it is hard to compare it with other agencies, since they mostly train divers with Type T rebreathers, In these courses it is imparative that you understands and can control your pO2. On the Typ R Rebreather you also need to understand it, but you cannot control it. So its like two different educations. I think that this is a part where many are having difficulties to see the difference.

    And you are correct about the warning bells, if it had been a Type T rebreather course. I am fully aware that it sounds like I am defending these courses, but its more like I am defending the Type R CCR and are at the same time open minded about the other more technical RB. One must fully understand the concept to be able to understand the requirements. But I agree that step 1 on the RAID course seems a bit low.

    So what you are saying is that you should really take (using PADI here) the AOW with an EANx certification, just to be able to dive 10 meters on your local reef? OW is not good enough.

    Ok, maybe not that drastic, but I guess you see my point.
    Last edited by Jeppe_E; 12th January 2012 at 18:38.

  4. #44
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    Re: Raid

    Holy Crapola!
    15 is the age limit on a CCR ? Thats crazy Talk,

    Jeppe e - I think the sum of the counter arguments you see by us "technical rebreather divers" Is that they believe the inherent complexity of a rebreather is too technical for a simple recreational course.
    A fine example. I was privvy to a conversation on an open water course (cause this course is the CCr equivalent to OW) where during a tables excercise, the student asked the instructor.. what happens if we exceed the NDL and accidentaly go into decompression? the instructors reply was
    " you will die"
    So my guess was the instructor was unsure or uneducated about deco theory and hadnt read the emergency deco part on erpdml. Point being, this student now, doesnt know why he cant exceed it, he just knows he'll die if he does. I'd hate to see his state of mind if he ever did end up in that situation...
    So I can see the questions and answers now " what happens if I exceed my 1.2 ppo2? "you will die"
    What is channeling? " the MK6 cant suffer channeling cause a machine packed the scrubber"
    Or a diver descends over the side of the wreck from 15m to 25m and having advanced open water level boyancy ocntrol.. descends fast to see the next part of the wreck.. the PPo2 spikes... the machine says "Bailout You're gunna die!" he bails out and wastes a dive, possibly runs out of DIL, or gets bent on the 18mpm ascent, or sufaces into a boat (cause he hasnt been shown how to float a bag and dont have ime on the 3L cyl) -- all because he dont understand whats goin on , and the comuter decided that its all gunna end

  5. #45
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    Re: Raid

    Quote Originally Posted by Jeppe_E  View Original Post
    So what you are saying is that you should really take (using PADI here) the AOW with an EANx certification, just to be able to dive 10 meters on your local reef? OW is not good enough.
    No... OC is really really simple.
    Failures are intuitive and obvious.
    A simple OC reef dive can be done by someone fresh off a course with very little risk.
    I don't think there's much point in me continuing the discussion if you don't see the difference between a 10m dive on OC and a 10m dive on a rebreather.

  6. #46
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    Re: Raid

    Quote Originally Posted by tecdiverdude  View Original Post
    Holy Crapola!
    15 is the age limit on a CCR ? Thats crazy Talk,
    Agreed

    Quote Originally Posted by tecdiverdude  View Original Post
    A fine example. I was privvy to a conversation on an open water course (cause this course is the CCr equivalent to OW) where during a tables excercise, the student asked the instructor.. what happens if we exceed the NDL and accidentaly go into decompression? the instructors reply was
    " you will die"
    So my guess was the instructor was unsure or uneducated about deco theory and hadnt read the emergency deco part on erpdml. Point being, this student now, doesnt know why he cant exceed it, he just knows he'll die if he does. I'd hate to see his state of mind if he ever did end up in that situation...
    A course is never as good as it's instructor. I feel bad for the students that got this answer from the instructor. Thats just plain stupid anyway you slice it.

    Quote Originally Posted by tecdiverdude  View Original Post
    So I can see the questions and answers now " what happens if I exceed my 1.2 ppo2? "you will die"
    What is channeling? " the MK6 cant suffer channeling cause a machine packed the scrubber"
    Yes well, now your dumbing the course and the instructor. The correct answer should be, you might die if you dont respond to the alarm, as you would with not respondning to a high/low pO2 on your sharewater. Disregarding the fact that the machine will tell you to bail out. The discovery makes sure it can read pO2 values up to 1.6 when passing 6m
    Channeling is taught and explained very well, also a part of the startup is checking your prepacked scrubber so it is packed thoroughly.

    Quote Originally Posted by tecdiverdude  View Original Post
    Or a diver descends over the side of the wreck from 15m to 25m and having advanced open water level boyancy ocntrol.. descends fast to see the next part of the wreck.. the PPo2 spikes... the machine says "Bailout You're gunna die!" he bails out and wastes a dive, possibly runs out of DIL, or gets bent on the 18mpm ascent, or sufaces into a boat (cause he hasnt been shown how to float a bag and dont have ime on the 3L cyl) -- all because he dont understand whats goin on , and the comuter decided that its all gunna end
    As we are (or at least I) are discussing diving the Discovery, it has a Dynamic setpoint. If you have descended to 15m it has just switched to deep setpoint of 1.2, it will maintain this setpoint. Even if you drop from the surface to 25 meters it will avoid pO2 spikes by its dynamic setpoint, starting at 0.5 at the surface and moving proportional (not linear) to the depth. When diving below 18 meter you should use an offboard bail out tank, like most RB diver does.

    You are getting a bit ridiculous here and adding basic diving skills to help your argumentation ;)

    The skill to making an emergency, or even a controlled ascent in free water has little to do with a rebreather, other than you need to empty your loop as an addition. If something goes wrong, you are back on OC, preferably on a 40 cuf or even an 80 cuf.

  7. #47
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    Quote Originally Posted by Jeppe_E  View Original Post

    As we are (or at least I) are discussing diving the Discovery, it has a Dynamic setpoint. If you have descended to 15m it has just switched to deep setpoint of 1.2, it will maintain this setpoint. Even if you drop from the surface to 25 meters it will avoid pO2 spikes by its dynamic setpoint, starting at 0.5 at the surface and moving proportional (not linear) to the depth. When diving below 18 meter you should use an offboard bail out tank, like most RB diver does.

    You are getting a bit ridiculous here and adding basic diving skills to help your argumentation ;)

    .
    Please explain how the Mk VI avoids the PO2 spike that results from rapid descents?
    Cheers,

    Dave....

    www.wedivebc.com

  8. #48
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    Re: Raid

    Quote Originally Posted by Steve Schultz  View Original Post
    I don't think there's much point in me continuing the discussion if you don't see the difference between a 10m dive on OC and a 10m dive on a rebreather.

    Of course I see and understands the difference between an OC and an Rebreather dive. But what we where discussing is the need for excessive training. Again, I am all for knowledge, but somewhere down the line one must say, this is what you need to know, and I believe that the PADI material together with the instructor has provided me with that knowledge. Then, as I strive for more knowledge, I improve my understanding for rebreather diving, But this is no more necessary than an EANx course for an OW diver who dives to 10 meters would be.

    But hey, thats my way of looking at it. As long as we all feel safe and enjoy our dives. Cheers

  9. #49
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    Re: Raid

    Quote Originally Posted by wedivebc  View Original Post
    Please explain how the Mk VI avoids the PO2 spike that results from rapid descents?
    The MkVI incorporates a dynamic PO2 setpoint value, which means the setpoint changes depending on depth and decompression status. Two setpoint settings control what the range of setpoint values will be during the dive. A “surface” setpoint value (default 0.5 bar / atm) establishes the PO2 setpoint when at the surface, and a “deep” setpoint (default 1.2 bar / atm) establishes the PO2 setpoint when at a depth greater than of 15 m / 50 feet. Between these two depths, the setpoint changes in small increments between these two values. Thus, when the depth is less than 15 m / 50 ft, the setpoint will be some value between the “surface” setpoint and the “deep” setpoint, proportional (but not linearly so) to current depth. This dynamic setpoint method helps prevent excessive PO2 “spikes” during descent, and excessive oxygen wastage during ascents from no-decompression dives.

    There are two exceptions to the dynamic setpoint method described above. The first is that whenever a decompression ceiling exists, the setpoint will not drop below 0.9 bar / atm during ascent. The second involves the Hyperoxic Linearity test on the primary oxygen sensor, as described below.

    One of the important new features in the MkVI Discovery is the Hyperoxic Linearity test. When the oxygen sensors are calibrated during the pre-dive routine (Chapter 2), the linearity of the oxygen sensor response is only validated up to a PO2 value of 1.0 bar / atm (i.e., 100% oxygen at sea level). Most rebreathers assume that the sensor response remains linear at higher values (operational PO2 setpoint values often exceed 1.0 bar / atm). However, in certain situations the sensors may not be linear above 1.0 bar / atm, which can lead to a very dangerous situation. For example, if the sensor is not capable of responding to PO2 values greater than 1.2 bar / atm, and the PO2 setpoint is 1.4 bar / atm, the control system may flood the breathing loop with dangerously high levels of oxygen while attempting to achieve a PO2 value that the sensors are not capable of registering.

    To overcome this problem, the MkVI Discovery performs a test on the primary oxygen sensor the first time a depth of 6 m / 20 ft is achieved. The test injects a short burst of oxygen directly onto the primary sensor to ensure the sensor response is linear up to a PO2 value of 1.6 bar / atm. If the test passes, then the dynamic setpoint performs as described previously (i.e., using up to the “deep” PO2 setpoint value when the depth exceeds 15 m / 50 ft.). However, if the Hyperoxic Linearity test fails, then the maximum allowable setpoint is set at 1.0 bar / atm. The reason for this is that the primary oxygen sensor is known to be linear to at least 1.0 bar / atm, based on the successful completion of the pre-dive calibration process. Thus, as long as the PO2 does not exceed 1.0 bar / atm, the response value is known with confidence.
    Using the default “surface” and “deep” PO2 setpoint values, a setpoint of 1.0 is not achieved until the depth exceeds 6 m / 20 ft, so there is no consequence on dives shallower than this depth, even if the Hyperoxic Linearity test is never performed. However, if the “surface” and/or “deep” setpoint values have been altered using the PC software, it is possible that a PO2 setpoint value can be established for depths less than 6 m / 20 ft. However, such higher setpoint values will not be allowed until after the diver achieves a depth of 6 m / 20 ft at least once during the dive, and the Hyperoxic Linearity test passes successfully. Until such time, the PO2 setpoint value will be limited to 1.0 bar / atm.


    You could probably get it to fail, if you provoke it by bombing down overweighted, but to be fair, who dives like that?
    Last edited by Jeppe_E; 12th January 2012 at 21:22.

  10. #50
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
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    That's all very good but most RB divers know that O2 spikes are a function of rapidly increasing of the partial pressure already in the loop and have nothing to do with setpoint control.
    Cheers,

    Dave....

    www.wedivebc.com

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