Use a gag strap?

[stuartv]

In addition, worth reading Paul Haynes article, ‘Increasing the probability of surviving loss of consciousness underwater when using a rebreather’, page 253 https://www.spums.org.au/file/574/download?token=SLGDpN2q#page=59

Obviously all military rebreather divers either have a gag strap (or FFM) fitted to their units. And EN14143 certification calls for them to prevent divers drowning in event of becoming unconscious. Which is why OSELs ALVBOV and DSV has to be supplied with a retaining strap fitted as a default, in addition to it just being a simple and cheap safety feature to offer.

Most telling is likely the sheer number of recreational rebreather divers whom have been recovered drowned; with their DSV/BOV out of their mouth. http://www.deeplife.co.uk/or_files/RB_Fatal_Accident_Database_100725.xls

As far as I can tell, that Haynes article contributes nothing to the question of whether a gag strap is really beneficial. The only data it cites is the French study that was previously linked. The article even acknowledges that beyond that French study it is just anecdotes and "logic".

 

[stuartv]

So the question remains - how likely is LOC compared to other events where a gag strap might be a problem if you don't have a BOV?

I think this question carries an unsubstantiated implication. IS there an event where a gag strap would be a problem, at all?

 

[rjack321]

A different bitepiece with longer bite tabs might alleviate that. Not sure.

I use one of the "mould to your teeth" ones on my Kiss. But you have to be very careful to not get one that has a smaller lumen or your WOB can go up. The drager gag strap mouthpiece has a huge hole

 

[rjack321]

I think this question carries an unsubstantiated implication. IS there an event where a gag strap would be a problem, at all?

None that I could ever come up with other than loss of mask due to conflicting straps.

I like my drager gag strap. I just don't want to use it without a BOV and I don't use a BOV in my SM CCR

 

[doctormike]

I think this question carries an unsubstantiated implication. IS there an event where a gag strap would be a problem, at all?

Yeah. No BOV and a CO2 hit. Apparently it can be incredibly hard to make that switch without a gag strap. I can imagine that it would be harder with one.

 

[stuartv]

I use one of the "mould to your teeth" ones on my Kiss. But you have to be very careful to not get one that has a smaller lumen or your WOB can go up. The drager gag strap mouthpiece has a huge hole

Yes. I emailed with DGX about whether any of their mouthpieces would fit the hole on a Drager DSV. They specifically suggested to NOT use their Seacure one. I have not been able to get confirmation that any of the moldable ones on the market are really big enough.

A buddy did recommend the JJ mouthpiece to me. He uses one on his X and said he has tried a number of different mouthpieces before settling on that one. I ordered one and will try it.

But, after reading the French study article and what some of the experienced people here on SB have posted, I am kind of thinking I might go back to using the stock mouthpiece with gag strap.

 

[stuartv]

Yeah. No BOV and a CO2 hit. Apparently it can be incredibly hard to make that switch without a gag strap. I can imagine that it would be harder with one.

This is what I was talking about earlier. Without a BOV, you still have to reach up and close the DSV before you take it out and stick the BO in your mouth.

I am uncertain that, with your hand on the DSV anyway, pulling it out and down onto your chin (with a gag strap on it) really does make it any harder to do than taking it out and letting it float up. But, I'm a newb, so what do I know, really?

I have done the switch to BO quite a few times. My training was to do that at the start of every dive, to confirm BO is on, working, and the hose is deployable and not tangled up with anything else. Taking the DSV out and down onto my chin just is not an issue - to me, anyway. THAT skill is not the reason I find the gag strap annoying.

I don't like the gag strap just because it's one extra thing to put on. It makes taking the DSV out to talk more of a pain. And when it's not on my head, the strap likes to catch on stuff.

 

[doctormike]

This is what I was talking about earlier. Without a BOV, you still have to reach up and close the DSV before you take it out and stick the BO in your mouth.

I am uncertain that, with your hand on the DSV anyway, pulling it out and down onto your chin (with a gag strap on it) really does make it any harder to do than taking it out and letting it float up. But, I'm a newb, so what do I know, really?

A lot harder, if you have a necklaced BO second stage that gets in the way. So I guess I could just bungee my BO second stage to my tank (some DSV divers do that, even for their deep bailout). But that sounds like adding more stuff to do during a period of relative incapacitation.

I have done the switch to BO quite a few times. My training was to do that at the start of every dive, to confirm BO is on, working, and the hose is deployable and not tangled up with anything else. Taking the DSV out and down onto my chin just is not an issue - to me, anyway. THAT skill is not the reason I find the gag strap annoying.

From what I understand (not from personal experience) skills that are trivially easy in training can become next to impossible during a CO2 hit. Which would be one of the reasons for bailing out.

I don't like the gag strap just because it's one extra thing to put on. It makes taking the DSV out to talk more of a pain. And when it's not on my head, the strap likes to catch on stuff.

Yeah, those are other things that I put in the "con" column.

 

[stuartv]

A lot harder, if you have a necklaced BO second stage that gets in the way. So I guess I could just bungee my BO second stage to my tank (some DSV divers do that, even for their deep bailout). But that sounds like adding more stuff to do during a period of relative incapacitation.

From what I understand (not from personal experience) skills that are trivially easy in training can become next to impossible during a CO2 hit. Which would be one of the reasons for bailing out.

From talking to my really deep diver buddy, he points out that he doesn't put a BO reg around his neck for several reasons. One, once you are carrying multiple cylinders, you need to switch to the correct one. Your bottom BO gas could possibly be hypoxic at a point you need to bail out shallower, for example, so just having one BO reg/gas for all situations is not an option. And, two, the training includes switching BO cylinders with your buddy once the person on BO breathes theirs down to half. Swapping doesn't work so well if the reg is around somebody's neck. The skill done in training is the same for all BO cylinders and does not include dealing with a BO reg hose that is around anyone's neck. And, as he says, "if you don't/can't drill on it, then you don't do it during a dive."

His training - and mine - included drilling to be able to deploy the OC reg from where it is stashed on the BO bottle very quickly. I will say that his training does also include having a BOV (on his X - his JJ training did not include having a BOV).

I do realize everyone's training is not the same and I'm not trying to say any one way is better than any other way. I'm just trying to discuss the different approaches, to help ME understand them better.

One thing that seems like it might be relevant is, if you're having a CO2 hit, you CAN stay on the loop for another second (or two or three) if you need to (I think), in order to switch to BO. And if your reason for switching to BO is something else, you probably aren't having the same mental or physical issues, such that pausing your breathing for a moment, if necessary, while you deploy and switch to a BO reg is a major problem. Which means, what I'm trying to say is that I'm not sure the time it takes to deploy a BO from a slung cylinder, versus switching to one on a bungee necklace is a "real" issue. Is it? I don't know. Maybe if you got really unlucky and just sucked a big mouthful of caustic, it could be a problem?

This is sort of OT from gag straps, but all of this is really making me lean more and more towards wanting to have a BOV. I know some people say that they are not needed and you should always detect an oncoming CO2 hit well enough in advance to be able to switch to BO without needing a BOV. But, is there really a downside? I mean, if you ARE able to detect the CO2 building up, you don't have to use the BO, right? You could have it and still dive as if it's not there.

 

[Dsix36]

I dive a rEvo and had a gag strap on the unit I was training on. I bought a year old unit without one and never used one since. I use a necklaced BO reg. I have suffered a CO2 hit, although it was not near as severe as it could have been, and it was damn near impossible for me to time my actions in order to not inhale water. I truly believe a BOV can be life saving in this and a couple of other instances, but do not want the added complications of having the proper gas plumbed in at the appropriate depth. Gas switches are just another place to kill yourself.

On a really bad CO2 day I can pull my BO reg loose and bring it above the DSV so that I can pull the DSV down rather than letting it float and flood. If you are in trim the unit will not flood so you will not HAVE to shut the DSV. Much quicker and easier to swap that way. Yes, I have tested this multiple times and know for a fact that it will flood fast if it goes over your head.

I have been diligently using Seacure mouthpieces since my start on the Draeger Dolphin. I learned about jaw fatigue on my first dive and my instructor told me about them. Night and day difference, even with a scooter. There is a way to use them on the rEvo without increasing the WOB, but it takes more than the printed instructions. The Seacue is not as secure as a gag strap but I have managed to fall asleep on deco more than once and never inhaled any water.

There are pros and cons to every aspect of RB diving. In the end you have to make the decisions on where your line between risk and reward is drawn. Just do not lie to yourself and think your loved ones will be OK without you.