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Rebreather Question from a non-rebreather user

Discussion in 'Rebreather Diving' started by maranda1389, Nov 6, 2010.

  1. Gill Envy

    Gill Envy Rebreather Pilot

    # of Dives: 500 - 999
    Location: Seattle, WA
    I hear ya, the first couple dry suit dives with the 5D this summer were a total cluster, I mean to the point of embarrassing. I've considered turning down the screw a little so the ADV works a little, though I have found the addition of the MAV block to be very handy... it puts all gas addition at a very convenient location... really should be standard on mCCR's, IMHO.
  2. bigblue_hi

    bigblue_hi Registered

    # of Dives: 100 - 199
    Location: Honolulu, Hawaii, United States
    What does "safe" mean anyway? People always want things to be safe but they don't quantify that. I think it's a stupid question to ask if something is safe.

    Eating many foods is not safe. Drinking alcohol is not safe. Are knives safe? What about my hammers? Are they safe? I gouged my foot the other day ripping up ceramic floor tile with the claw-end of my hammer. No big deal - but does that mean the hammer was unsafe? No it just means I was using it improperly and had not taken adequate safety precautions.

    Familiarity breeds complacency and acceptance of risks. Rushing means we skip checks assuming "it will be fine" - and it usually is.. except when it's not. Most rebreather deaths spring from these two causes.

    Driving is incredibly dangerous - we let all sorts of people get behind the wheel of a vehicle that may weigh several tons and can go over 100mph easily and routinely 60+. Can you kill someone with a car? Yes. Can you kill yourself? yes.

    Do most people operate these safely most of the time? Yes. And we trade the benefits for the risk.

    It's the same with diving. There are risks inherent to any venture. I'm tired of people asking if this or that is "safe". Everything has risk. It's up to you decide which voluntary ones are within your comfort zone. Don't want any risk when diving? Don't do it! Just means you'll die another way.

    A properly setup and operated rebreather is safer than a complacent OC diver. I think the biggest risk factor for rebreather diving is that is too easy to get comfortable. The equipment does it all for you! And does such a great job most of the time! But nothing is perfect.. so be vigilant. You can stay down for hours on pretty much any unit without any special configuration. You can get yourself in a lot more trouble during that time than the typical single AL80 OC diver. They are also much less forgiving of a rushed/poor setup. OC diving basically involves connecting a regulator to a hose and sticking it in your mouth. I'll spend more time parking than anything else while diving OC.

    However this isn't the fault of the unit - it's the people involved. You see the same sorts of things looking at hikers versus snowmobiles/ATVs. Any idiot can get one and drive off into the middle of nowhere and flip it. Getting far away from civilization on foot takes a heck of a lot of perseverance.

    Equipment is dangerous when it takes the individual well beyond the limit they can recover from themselves.. were it to fail.

    So if you're not the type of person that can handle the additional complexity and responsibility for the rewards - then it is not for you. Doesn't make you a bad person or anything. Just...

    Know your limits.

    PS: This isn't really targeted at you Gill, just happened to reply to your bit of the thread.
  3. JDostal

    JDostal Divemaster

    # of Dives: 500 - 999
    Location: Wisconsin
    Yep, you can use a rebreather at any depth. I've got a few two hour practice dives at 20 feet deep on my ccr in the logbook. Just need to be vigilant.
  4. caveseeker7

    caveseeker7 Rebreather Pilot

    Has your question been answered or are you wondering more than when you posted the question?
    I'll give it a shot.

    First off, not every rebreather can be used at any depth. Different types of rebreathers were developed for different needs.

    The O2 rebreathers used by combat swimmers are a tool for moving stealthily below the surface. For that they work well, and are also used by researchers, film makers etc for shallow water diving. Shallow water being 6 meters/18 feet or less. And before some jumps in and argues that they're taken much deeper than that by the military its simply a matter of training and taking chances. When the alternative is getting shot at or captured, the risk of O2 toxicity becomes a much more viable option.

    In general it is, IMHO, not a good idea to equal military and civilian rebreather use. Military use of rebreathers is restricted to very specialized assignments, may it be EOD work or moving about unseen, and both the quality and the quantity of the training don't compare to civilian rebreather classes. Most importantly, the state of mind and level of discipline don't quite compare in most cases I believe. Last but not least, the diving protocol for mixed gas rebreathers is on a very different level in the military compared to the average CCR outing.

    Rebreathers developed for using only pre-mixed gas or gases can be operated in the depth range(s) of the respective gases, same as open circuit. Those are usually semi-closed rebreathers, their purpose range from recreational (like the Dolphin or UBS 40) to extreme deep cave exploration.

    Mixed-gas rebreathers are, as the name replies, gas mixing machines carried along by the diver. Depth range depends on the gases used, for recreational diving depths usually O2 and air (= nitrox), for deeper dives trimix or heliox.

    Within those ranges rebreathers can be used. If your "SAFELY" is supposed to mean failsafe, I'm afraid none of them is. Neither are the divers using them. A fatality with a rebreather for "recreational" diving has occurred in a pool, with a "deep cave exploration" unit in less than 10 feet of water. Victims of fatal rebreather accidents have ranged from more or less untrained, uncertified, to well trained and highly experienced on their respective units.

    As I said, rebreathers can fail, and so can their divers.
    Something rebreather diving shares with open circuit diving, actually.

    Hope that helps.
  5. novicediver

    novicediver Solo Diver

    Is the diver fatality rate for CCR's significantly different between the very experienced user vs the more moderate user? I have not seen any numbers nor am I an experienced enough diver to render an opinion either way. At one point on a thread, a poster stated that CCR's are analogous to flying a plane in that you have to use a written checklist every time and that no steps be skipped. I would suspect the fatality rate for very experienced users is due to complacency.

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