Use a gag strap?

[JohnnyC]

The EAC is like a pack of straws. Full of axial holes. Does it allow uneven flow across the cross section more easily than with a granular scrubber?
Maybe EAC works bad in units which have not been properly designed for EAC and even flow across the cross section.

I know that the support divers who had a movie Meg on The Cave got hit when they used the EAC's with the adapters. So they went to granular scrubber and no more problems.

 

[LFMarm]

I wonder if the discussion from Pete Mesley Equipment Options For Rebreather Diver Safety will make more divers try it. It’s on my plans for this year

 

[mr_v]

I updated my vote, as I have recently started diving without a gag strap. Initial impressions - it is not that bad, but I'd love for rEvo DSVs to accept standard sized mouthpieces at some point. The biggest hassle was finding a mouthpiece that did not require a medieval torture stretching device.

Haven't noticed a substantial change in WOB with a JJ mouthpiece. Taking loop out and putting it back in are noticeably faster. The loop is cleaner and there is less risk of the gag strap getting caught on deck railings and other fixtures.

2 hour dives are perfectly fine. I can see how 3-4 hour dives may cause extra jaw muscle stress. Overall, I am fairly happy to go with or without a strap.

 

[LFMarm]

I also just updated the vote but in the opposite direction. I am going to start diving with a gag strap after watching this video from Pete Mesley Rebreather Forum 4

 

[rjack321]

I also just updated the vote but in the opposite direction. I am going to start diving with a gag strap after watching this video from Pete Mesley Rebreather Forum 4

Updated my vote too, I have BOVs on both my Meg and my Kiss so I am using a gag strap on both now. I stuff the short hose left reg on the sidewinder

 

[sprockjohnson]

I had a gag strap on my rEvo DSV when I first bought it but stopped using it due to the difficulty in switching to my necklaced BO regulator. I did not have one on my Sport KISS which had the factory BOV and after diving with that several times wished I did have one due to jaw fatigue with the extra weight of the BOV. I have since changed to a rEvo BOV with a gag strap on the rEvo and a DSV without one on the KISS.

Having had to bailout somewhat recently on the KISS due to poor gas density planning I was glad there wasn't a gag strap to fumble with when retrieving my necklaced BO regulator.

 

[stuartv]

I had a gag strap on my rEvo DSV when I first bought it but stopped using it due to the difficulty in switching to my necklaced BO regulator. I did not have one on my Sport KISS which had the factory BOV and after diving with that several times wished I did have one due to jaw fatigue with the extra weight of the BOV. I have since changed to a rEvo BOV with a gag strap on the rEvo and a DSV without one on the KISS.

Having had to bailout somewhat recently on the KISS due to poor gas density planning I was glad there wasn't a gag strap to fumble with when retrieving my necklaced BO regulator.

In my rEvo MOD1 training, my instructor had me take the DSV out and stick it just under my chin (gag strap still in place) and insert my BO reg. Once breathing on BO, then there is time to "clean up". I never had any trouble or felt slowed down by that process. The rEvo head strap is plenty stretchy to accomplish that, even on my (very) XL head.

I changed to the rEvo BOV later (and also a bungee necklace for my bottom mix BO) and used that for 2 or 3 years. Earlier this year, I went back to just a DSV (but still with BO bungee necklace). I had a few different problems with the BOV. I decided it was too much trouble and, particularly on a rEvo, just not needed.

 

[cathal]

I had a few different problems with the BOV. I decided it was too much trouble and, particularly on a rEvo, just not needed.

Grateful if you could explain why a BOV is not needed on a rEvo?

 

[stuartv]

Grateful if you could explain why a BOV is not needed on a rEvo?

Not needed in general. Numerous very experienced CCR divers and CCR instructors have told me over and over that, if you pay attention you should never get so hypercapnic that you cannot simply switch from a DSV to an OC BO reg. You should recognize the onset of hypercapnia before it begins to affect you so badly that you cannot make yourself take the DSV out of your mouth to put the BO reg in.

Particularly on a rEvo because of the dual scrubber design. As long as you are not a moron who dives your sorb past its safe use limit, you should never have channeling or breakthrough to cause you to go hypercapnic.

So, on a rEvo in particular, the only ways you should ever be at risk for going hypercapnic are mushroom valve failure or working too hard. Doing a proper stereo check on the loop pre-dive should mitigate the risk of mushroom valve failure during a dive. Paying attention to what you are doing and what your body is telling you should mitigate the risk of hypercapnia from working too hard.

Now, don't get me wrong. I'm not saying that a BOV has NO value. I do believe that a good BOV, with a head strap, and connected to a big supply of BO gas is the safest way to dive a CCR. But, I also believe that the risk, to a competent CCR diver is small enough to be balanced by the various downsides of using a BOV.

In other words, I will certainly not say you're "wrong" to use a BOV (or not use a BOV). I'm just saying that I have been there, done that, and found no reason to continue to go against the much more experienced voices telling me that I did not need a BOV and should get rid of it. It is definitely more convenient and pleasant to not have the BOV on my loop.

 

[cathal]

Not needed in general. Numerous very experienced CCR divers and CCR instructors have told me over and over that, if you pay attention you should never get so hypercapnic that you cannot simply switch from a DSV to an OC BO reg. You should recognize the onset of hypercapnia before it begins to affect you so badly that you cannot make yourself take the DSV out of your mouth to put the BO reg in.

Particularly on a rEvo because of the dual scrubber design. As long as you are not a moron who dives your sorb past its safe use limit, you should never have channeling or breakthrough to cause you to go hypercapnic.

So, on a rEvo in particular, the only ways you should ever be at risk for going hypercapnic are mushroom valve failure or working too hard. Doing a proper stereo check on the loop pre-dive should mitigate the risk of mushroom valve failure during a dive. Paying attention to what you are doing and what your body is telling you should mitigate the risk of hypercapnia from working too hard.

Now, don't get me wrong. I'm not saying that a BOV has NO value. I do believe that a good BOV, with a head strap, and connected to a big supply of BO gas is the safest way to dive a CCR. But, I also believe that the risk, to a competent CCR diver is small enough to be balanced by the various downsides of using a BOV.

In other words, I will certainly not say you're "wrong" to use a BOV (or not use a BOV). I'm just saying that I have been there, done that, and found no reason to continue to go against the much more experienced voices telling me that I did not need a BOV and should get rid of it. It is definitely more convenient and pleasant to not have the BOV on my loop.

Thank you for the detailed reply. Unfortunately plenty of very experienced CCR Divers and Instructors have been victims of human error. It affects divers, surgeons, pilots etc. Thats why they used the word 'should' when they told you above there was no need for BOV. The rEvo dual scrubber can be overcome. I have a rEvo and I once managed to overbreathe the scrubber because of a panic attack at 50M. No one can say for cvertain that they wont succome to human error. Just my 2C.