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Old 28th February 2012, 07:21   #1 (permalink)
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Does a Full Face Mask Represent a Major Jump in Safety on CCR?

I've been certified on my Inspiration for about 3 years and I've only done about 40-50 dives on it, primarily because it scares the sh*t out of me. I've done extensive certification from fabulous instructors through CCR Trimix. I know there's a lot of back-and-forth about risk studies, but I'm just about convinced that the odds of dying on my Inspo (if dived regularly for several decades) approach one-in-ten. Please don't ask how I arrived at that number because I'm sure it's debatable and because I'd love to gather some wisdom about full face masks. Let's just say CCR is way, way, way more dangerous than recreational OC.

I'm wondering if a full face mask represents a significant jump in safety given my particular dive profile. Here's the profile -- and I very rarely stray from it. My buddies and I dive Hawaii at shallow depths almost never exceeding 200 feet and we never dive vertical real estate ('cause it's nowhere to be found where we dive.) I always dive with several buddies in buddy pairs. I usually dive with Trimix. I always carry sufficient bailout. I dive an OCB, which I would hook up to my off-board bailout in case of an FFM.

My thinking: the greatest jump in risk from recreational OC to CCR is the much-heightened risk of passing out which equals expelling the mouthpiece which equals drowning. Passing out may be from CO2 buildup, O2 toxicity or hypoxia. In any case, especially in the first two cases, if a buddy finds me passed-out before several minutes has passed -- which would happen 100% of the time in my case -- that buddy could flip me to my bailout and start ascending with me. That seems like a huge jump in safety over expelling my mouthpiece and drowning.

If I'm right, then why wouldn't everyone use a FFM?

The newest FFMs are designed to minimize the chance of CO2 buildup in the mask space. Plus, the addition of comms, and the addition of a comm on my boat, would radically reduce the practical risks of DCS. More frequently than I like to admit, my OC buddies (diving deco) run themselves out of deco gas due to poor dive discipline and someone has to make a run to the surface to call down more gas, after we've buddy breathed for a while. (Yes, I know. Sometimes these are the same dudes I'd be counting on to find my unconscious body in the scenario above.) With comms, we can call for deco air, tell the boat when we get blown off our spot, etc..

What am I missing here? What's the jump in safety, if any, in diving CCR on a FFM in my case?

Thank you for sharing.
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Old 28th February 2012, 07:40   #2 (permalink)
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Re: Does a Full Face Mask Represent a Major Jump in Safety on CCR?

If you'll bear with me, I'll be a little more specific. ASSUMING that the potential injury/death rate is 1-in-10 over 30 years (and I'm positive that there's a hellacious debate that could surround that question) but just holding that assumption as a theoretical baseline, let's divide that risk:

50% heart attack or stroke (which could happen anyway)
40% failure to maintain and/or prep my CCR (that would lead to one of the following)
10% mechanical failure

And direct cause of death (before drowning) of the last 50% above:

14% CO2 buildup
14% Hyperoxia
14% Hypoxia
4% CO poisoning (from bad air)
3% Caustic Cocktail (I don't even know how you die from this directly)
1% Vampires, Aliens and/or Politicians Attacking

CO2 buildup: I'm pretty sure that it takes hours of CO2 buildup to become permanently damaging, though it does take a while to get out of your system. If someone flips me to air in a few minutes, it seems like this risk is virtually eliminated as a cause of death.

Hyperoxia: since O2 toxicity is virtually harmless unless you drown, it seems like a switch to bailout (and reduction in workload) would 100% resuscitate a convulsing diver -- unless the FFM got knocked off in the process of convulsing.

Hypoxia: low levels of O2, of course, will kill, but there is between 3 and 5 minutes grace even if the O2 level is zero. With low O2, the grace period should be much longer. Again, the FFM should largely eliminate this risk.

CO Poisoning: again, unconsciousness leading to eventual death. If I don't drift into much deeper water, it seems like a CO buildup would be survivable so long as I didn't drown. Once again, the FFM seems like a solution.

Caustic Cocktail: due to reluctance to abandon the mask, this risk could be slightly elevated. But how would that kill you and why wouldn't you just dump the mask, go to an OC reg and grab your backup mask? This requires another reg on your rig (which maybe doesn't work in wreck and cave) but that's no problem in our open water scenario.

It seems like the FFM eliminates most of the CCR-specific risk. What am I not seeing?

Thanks!
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Old 28th February 2012, 08:32   #3 (permalink)
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Re: Does a Full Face Mask Represent a Major Jump in Safety on CCR?

Quote: (Originally Posted by BeachMusic) View Original Post
If you'll bear with me, I'll be a little more specific. ASSUMING that the potential injury/death rate is 1-in-10 over 30 years (and I'm positive that there's a hellacious debate that could surround that question) but just holding that assumption as a theoretical baseline, let's divide that risk:

50% heart attack or stroke (which could happen anyway)
40% failure to maintain and/or prep my CCR (that would lead to one of the following)
10% mechanical failure

And direct cause of death (before drowning) of the last 50% above:

14% CO2 buildup
14% Hyperoxia
14% Hypoxia
4% CO poisoning (from bad air)
3% Caustic Cocktail (I don't even know how you die from this directly)
1% Vampires, Aliens and/or Politicians Attacking

CO2 buildup: I'm pretty sure that it takes hours of CO2 buildup to become permanently damaging, though it does take a while to get out of your system. If someone flips me to air in a few minutes, it seems like this risk is virtually eliminated as a cause of death.

Hyperoxia: since O2 toxicity is virtually harmless unless you drown, it seems like a switch to bailout (and reduction in workload) would 100% resuscitate a convulsing diver -- unless the FFM got knocked off in the process of convulsing.

Hypoxia: low levels of O2, of course, will kill, but there is between 3 and 5 minutes grace even if the O2 level is zero. With low O2, the grace period should be much longer. Again, the FFM should largely eliminate this risk.

CO Poisoning: again, unconsciousness leading to eventual death. If I don't drift into much deeper water, it seems like a CO buildup would be survivable so long as I didn't drown. Once again, the FFM seems like a solution.

Caustic Cocktail: due to reluctance to abandon the mask, this risk could be slightly elevated. But how would that kill you and why wouldn't you just dump the mask, go to an OC reg and grab your backup mask? This requires another reg on your rig (which maybe doesn't work in wreck and cave) but that's no problem in our open water scenario.

It seems like the FFM eliminates most of the CCR-specific risk. What am I not seeing?

Thanks!
Firstly, I think it is a healthy thing to have a little fear - keeps you on your toes!

Secondly, in my view, you have missed out the biggest killer - panic.

I believe that understanding one's equipment down to it's tiniest detail, removing SPOF, and above all training for various scenarios mitigates most of the issues on your list by eliminating as far as possible the panic that actually does the killing.

In the case of a FFM ( I use the panorama myself) There is no way I would want to abandon my mask unless it was physically damaged and even then because of the in internal mouthpiece, chances are I could still dive it at least until I got my shit together. Using a switch I have access to both back gas and b/out at the flick of the switch. I also have umbilical that I can unplug from one source to another on the fly and get a another source of gas.

If you dive a hybrid you have so many different options to avoid most of the other bits on the list as well. Good electronics, a HUD, redundant PO2 monitor and uncompromising pre-dive and kitting up drills I think contribute the most to one's survival. Personally, I can't understand why all electronics don't have wet switches (mine does) not that I've forgotten to turn anything on so far, it just removes one area of potential issue.

I spent an awful lot of time in the pool getting to understand my unit and making sure that changes I made actually work before going deep.

For what it's worth, I honestly can't see me diving the unit without my FFM and BOV. These are critical parts of my bail-out solution.
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Old 28th February 2012, 08:39   #4 (permalink)
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Re: Does a Full Face Mask Represent a Major Jump in Safety on CCR?

I use a FFM because
a) I feel that it does increase safety for the reasons that you mentioned (whether or not it is a Major Jump I don't know but it is a sufficient enough increase in safety for me to buy and use one).
b) because it reduces/eliminates jaw fatigue
c) reduces heat loss when diving in cold water

Regarding the caustic cocktail situation you mentioned I don't see that as an issue for me as I use the Kirby Morgan M-48 mask which has the removable lower pod so I can ditch the rebreather loop altogether without removing the whole mask.
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Old 28th February 2012, 09:42   #5 (permalink)
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Not really specific to OP, but something to consider as it has sort of been mentioned:
I build very mission specific Rebreather's for a day job and the standard configuration build is a modified FFM with BOV and an OC demand reg. ie double redundancy.
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Old 28th February 2012, 11:07   #6 (permalink)
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Re: Does a Full Face Mask Represent a Major Jump in Safety on CCR?

Quote: (Originally Posted by bentdiver80) View Original Post
Not really specific to OP, but something to consider as it has sort of been mentioned:
I build very mission specific Rebreather's for a day job and the standard configuration build is a modified FFM with BOV and an OC demand reg. ie double redundancy.
Do you have more info available on that FFM? Do you also sell them without the Rebreather. I was considering the new KM 48 mod but yours sounds nice to.
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Old 28th February 2012, 11:35   #7 (permalink)
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Re: Does a Full Face Mask Represent a Major Jump in Safety on CCR?

I use Interspiro/AGA FFM with bov. No problems.
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Old 28th February 2012, 11:41   #8 (permalink)
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Re: Does a Full Face Mask Represent a Major Jump in Safety on CCR?

I personally never understood the "hype" with FFMs in recreational diving nor do I think they are a step towards safer Rebreather diving. The use of FFMs is normally needed when any of the following situations or conditions occur: diving in cold water, contaminated water or if comms are needed.

In general, FFMs add more volume hence drag and introduce an added level of complexity in systems that are already some distance from "simple" OC.

IMHO, the best way to improve Rebreather safety is to integrate a BOV connected to a sufficient volume of OC breathable gas that is accessible at all times with the flick of the lever.

(Yes, it goes without saying you also need to be properly trained, experienced and mentaly fit enough for the dives you do, having the right gases onboard and with a fully functioning unit. But this is just common sense, isn't it?)

Just my 2 cents...

/GKAM

P.S.: This is the real issue with diving these days; equipment has become so reliable and fault tolerant people may get away with all kinds of stupid setups and/or inadequate training for hundreds of dives over many years. It is just a question of time until something fails and they are simply unable to handle the situation.
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Old 28th February 2012, 12:14   #9 (permalink)
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Re: Does a Full Face Mask Represent a Major Jump in Safety on CCR?

my unit scares me every time i touch it, its why I bought an MCCR!!!
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Old 28th February 2012, 13:34   #10 (permalink)
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Re: Does a Full Face Mask Represent a Major Jump in Safety on CCR?

a FFM stops the diver from breathing water in case he/she looses consciousness (as breathing water is mostly the cause of death, nearly never breathing a wrong gas...)

but

a FFM adds a lot of complexity to the rig, the setup, the connections, the dive procedures, buddy procedures etc ..

I think you must be quite familiar with diving a rebreather, before you start diving a rebreather with a FFM

so in the mean time, you can use a gag strap correctly attached to your head: it does not give you the same thing as a FFM, but it has quite some advantages, and is far less complex to start with

I have a panorama nova R, but can not use it a lot, as when teaching, it's impossible to use..
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