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Thread: Pure O2 CCR Dive Time and Depth limits.

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    New Member Lure_Angler is an unknown quantity at this point Lure_Angler's Avatar
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    Pure O2 CCR Dive Time and Depth limits.

    Dear all,

    I've been reading the US Navy Diving manual and at the same time cross referencing it with Britsh (1964. BR 2806) and Australian (1966. ABR 155) Navy Diving manuals.

    In the US manual, they have somethng called single depth limits. Some of the max dive time and depth limits it suggested are as follows:

    25 ft --> 240 minutes
    30 ft --> 80 minutes
    35 ft --> 25 minutes
    40 ft --> 15 minutes

    However, the Britsh and Aussie manuals mentioned nothing about such limites. The only thing they mentioned was the 25 feet maximum depth limit. No mention about maximum dive time at that depth.

    My question is: Are the times and depth limits as sugested by the US navy accurate and safe? Why is it that the other navies don't have them? I am particular interested in the validity of the 25 feet/240min and 30 feet/80min limits.

    My theory is this: I think they are safe if the US navy (which is published more recently , I suppose) have the equipment and capability to extensively test the limits which was not available to the other older navy diving manuals.

    TC

  2. #2
    Decodiver
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    Re: Pure O2 CCR Dive Time and Depth limits.

    Hi TC,

    What you need to bear in mind with military diving manuals, is that when the military break a diver they just ask stores to send them another one.

    Please be vey careful with applying military dive solutions to the civilian diving world.

    Rarely will you have the kind of support that the USN have for their operations and as such any slip-up you have will not be managed as quickly nor, I respectfully suggest, as thoroughly.

    If you want to see the reasoning behing my advice I suggest you secure a copy of Oxygen and the Diver, by Kenneth Donald.

    Military exposures are often in extremis for good clear operational need, ie we were cleared for one 45 second exposure to a maximium of 40 metres in extreme circumstances.

    I for one, would not agree that the times given are accurate or safe and I would caution that you will find it hard to get someone on this forum to confirm that for liability reasons.

    My advice would be never to run an exposure of 1.6ata on O2 for more than 45 minutes, as is widely accepted by most training agencies, for good reason.

    Oxygen will kill you if you turn your back on it underwater.

    Dive-safe and take care.

    Cheers,

    Dave Cooper.

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    Banned MB is an unknown quantity at this point MB's Avatar
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    Re: Pure O2 CCR Dive Time and Depth limits.

    Quote Originally Posted by Decodiver  View Original Post
    Hi TC,

    What you need to bear in mind with military diving manuals, is that when the military break a diver they just ask stores to send them another one.
    .


    And I can say, with * a personal high level of experience in the safety culture of the US Navy* that they will do ***anything*** to prevent risk to a diver, thus I must respctfully say that the above statement is not in keeping with my own experiences. USN protocols tend to be VERY conservative, not the other way around. 130 feet maximum depth on a Mark-15 is an example....


    1.6 for 45 minutes is good advice though as is the rest of what was written.



    Dave ******

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    RBW Member jcolley is on a distinguished road jcolley is on a distinguished road jcolley's Avatar
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    Re: Pure O2 CCR Dive Time and Depth limits.

    Although not a Navy diver myself, I have a couple of good friends who are Master Divers and teach at the Panama City facility. I work with Navy Divers on a regular basis in my line of work and compound the safety concerns of commercial type diving with potential ratiation exposure concerns. I can tell you that from my experience, I have never met a more safety conscious organazation with the possible exception of the submarine force. Navy dive and salvage units frequently lose bids for contracts because the civilian contractors can get the job done because they are willing to take certain risks that the Navy diving community will not.

    I can not speak with any experience about any other country's military diving programs, but I can say that from many recreational dives with my Navy buddies, they are usually far less comfortable taking any chances with anything on a dive than I am myself and I don't consider myself to be reckless by any means. I would absolutely put faith in the their manuals and the research behind it.

    If the diving community's procedures are written anything like my own community's, there are many thumbrules that are used and although they may not list the actual basis for some of them, they are generally quite conservative.

    Just my $0.02...

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    New Member Lure_Angler is an unknown quantity at this point Lure_Angler's Avatar
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    Re: Pure O2 CCR Dive Time and Depth limits.

    Dear all,

    Of course, I will restrict myself to the more conservative, widely accepted limits, until I get more exp. The purpose of asking these questions is for the worst case scenario. Should I get into shit depths, at least I know what to do. It is also for the benefit of more goons that will come in future.

    However, it seems to me, even with the simplest of all CCR designs, there are disputes about its use and the technicalities.

    Once again, I thank all "Do-That-And-You'll-Die" advice given to me.

    Now, where's the Kenneth Donald book.....

    TC

  6. #6
    Decodiver
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    Re: Pure O2 CCR Dive Time and Depth limits.

    Dave and Mr Colley,

    No insult intended towards the US Navy, I am ex-Military myself (left 14 years ago), my point is that where necessary military needs will cause divers to be exposed to danger, I know this from personal experience.

    Also todays culture of safety is somewhat different to that which was implemented a number of decades ago when a lot of this was written.

    Cheers,

    Dave Cooper.
    Last edited by Decodiver; 28th November 2006 at 13:07.

  7. #7
    Decodiver
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    Re: Pure O2 CCR Dive Time and Depth limits.

    Quote Originally Posted by Lure_Angler  View Original Post
    Now, where's the Kenneth Donald book.....
    You are gonna have fun reading it, especially his conclusion that everyone's tolerance changes constantly from day to day. It is a great read because it gives metrics for manned dry and wet, working and rest dives and gives some tremendous information on oxygen seizures, what to look out for and evidence that coming from a high O2 exposure to a low one will not stop you fitting 30 seconds later.

    It should be compulsory reading for all CCR divers.

    Cheers,

    Dave Cooper.
    Last edited by Decodiver; 28th November 2006 at 13:31.

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    RBW Member jcolley is on a distinguished road jcolley is on a distinguished road jcolley's Avatar
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    Re: Pure O2 CCR Dive Time and Depth limits.

    Dave,

    No insult taken and I don't completely disagree with you. The manual and regulations are all quite clear and written with safety as the utmost concern. As long as the manals are followed, safety is not an issue. As anyone who has served knows, there are should we say *stressful* times when a decision must be made to go outside the limits of what is provided by the manual and that is where hopefully good judgement balances the true importance of the decision to violate the procedure with the need to accomplish the task.

    I feel though that we may have hijacked this thread and provided little useful input though.

    If someone here can not answer the original question, I will call a buddy of mine who probably had a small part in writing parts of that manual and ask what the basis was for some of those limits.

    Jim

  9. #9
    Decodiver
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    Re: Pure O2 CCR Dive Time and Depth limits.

    Quote Originally Posted by jcolley  View Original Post

    If someone here can not answer the original question, I will call a buddy of mine who probably had a small part in writing parts of that manual and ask what the basis was for some of those limits.

    Jim
    Now that is a good idea Jim.....have some green:D

    Cheers,

    Dave.

  10. #10
    New Member Lure_Angler is an unknown quantity at this point Lure_Angler's Avatar
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    Re: Pure O2 CCR Dive Time and Depth limits.

    Quote Originally Posted by jcolley  View Original Post
    Dave,

    No insult taken and I don't completely disagree with you. The manual and regulations are all quite clear and written with safety as the utmost concern. As long as the manals are followed, safety is not an issue. As anyone who has served knows, there are should we say *stressful* times when a decision must be made to go outside the limits of what is provided by the manual and that is where hopefully good judgement balances the true importance of the decision to violate the procedure with the need to accomplish the task.

    I feel though that we may have hijacked this thread and provided little useful input though.

    If someone here can not answer the original question, I will call a buddy of mine who probably had a small part in writing parts of that manual and ask what the basis was for some of those limits.

    Jim
    Dear Jim and All,

    No no, I think the posts have added a lot of insight. More insight, more knowledge.

    By the way, the US Navy Diving manual I'm reading came from here. Its the first entry when I googled the words "US Navy Diving manual" :

    U.S. Navy Diving Manual
    Last edited by Decodiver; 28th November 2006 at 13:17. Reason: Formatted link

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