I was diving my rEvo down in Pompano Beach in August. My last dive of the trip was a hot drop on the Miller Lite. I'm going to just summarize what happened.
On the way down, I realized that my BOV was leaking dil into the loop. I could feel it blowing gently into my mouth. I knew the O-ring that surrounds the opening through the barrel into the loop had popped out of its groove. I continued to drop to the bottom as I repeatedly opened and closed the loop, trying to get it to open with the O-ring back in its groove, so it would seal. I could feel the problem with my tongue stuck through the mouthpiece and tried to push the O-ring into place with my tongue as I slowly opened the loop. No luck.
I got to the bottom (157') and parked myself on the sand, with my 2 buddies right there with me, watching me but not really knowing what was going on.
While I was still working on it, knowing I was losing dil, I saw red flash in my NERD display. I focused on it and saw it was telling me that my Dil was down to Critical Pressure (of 50 bar). I knew I was losing dil, but I had no idea I was losing it that fast. Yes, my BOV was plumbed directly to my onboard 3L of dil. Save your breath on that, please. This is not the thread for that.
At that point, I signaled my BOV was broken and thumbed the dive. I shut off my dil at that point, to save some for inflating my wing when I got to the surface, and managed it manually for the rest of the dive. I got back on the boat with very little - but still SOME - dil left.
However, and this is the point, were it not for my AI setup, I very likely would have run out of dil on the bottom before I realized how fast I was losing it. And to be clear, the point is nothing to do with how or why I was losing dil - there are many ways one could be losing it and, even if you know you are, you might not realize how quickly. I was working the problem and would have checked my dil pressure once I got it sorted - which would have been too late, if I had not had a setup to flash a warning right in my face.
According to my downloaded log, it took me 2 minutes to descend to 157' and then I was 4.5 minutes on the bottom trying to fix it before I started back up. The time on the bottom felt more like 1 minute. My dil was TX14/41, so I was as clear-headed as I get. I had plenty of BO gas that I could have plugged into the loop and/or my wing inflator, had I needed to. My buddies were right with me. So, I was never in any serious danger. But, I'm still very glad my NERD and AI setup contributed to saving me from letting my problem get worse for me.
Further notes:
On the surface, I learned of another problem that happens when the BOV/DSV has a leak from the loop to the outside world. I pumped my loop full of O2 on the surface. 2 or 3 breaths later and I couldn't pull a breath from the loop. Pumped it up with O2 again. 2 or 3 breaths later, same thing. I realized that my counterlungs being in the water and my BOV being out of the water meant that hydrostatic pressure was squeezing all the gas out of my loop through the leak in the mouthpiece. As long as I stayed on the surface, the loop was not going to flood, but it did mean I was having to pump my wing pretty much full just to stay there. Had I descended, I believe my loop would have then flooded making me even more negative.
The O-ring in question is one that has a direct counterpart in a regular (Drager/rEvo) DSV, so the same root problem (a leak into the loop through the mouthpiece) could happen with a DSV.
I have decided to listen to "my elders"
D LOL) and change back to a standard DSV. No more BOV, at least for now. So, everyone that had a mild conniption when I said I had my BOV plumbed to onboard dil can relax now. Nobody I've talked to has ever been able to clearly articulate to me why a BOV plumbed to onboard - and DIVED as if there was no BOV at all - is any worse than actually having no BOV. Tell me it's bad? Yes. Plenty of times. Clearly articulate why (if treated as if there were no BOV at all)? Haven't heard it yet. No offense to the several of you who probably are thinking "yes, I did explain clearly why." I'll accept this as a ME problem (not understanding), not a you problem.
However, some very experienced CCR divers/instructors whom I greatly respect and who are doing the kinds of dives I want to do (and who I know and have dived with in real life) all dive with no BOV. So, I have tried the BOV and now I'm going to bow to greater experience and go without. If I don't need a BOV, then not having one is SIMPLER than having one and diving as if I don't. And simpler is better. Taking a lesson from Steve Lewis' book, The Six Skills, I don't need it, so I'm not taking it in the water.
I've seen posts from people in the past saying, either, "I never look at my CCR cylinder pressure gauges when I'm in the water" or, "I don't even have pressure gauges on my CCR." This experience has made it clear to me (as if it wasn't already) that I would certainly want to have them. Had I been able to get my BOV to seal up early on, I could have verified that I still had plenty of dil left and then proceeded with my dive plan. Or I could have seen that I got it fixed but lost too much dil and so needed to end the dive early.
Being able to check onboard cylinder pressures seems mandatory, to me. Actually checking them during a dive, also seems like an important thing to do more often than some people claim to. Regardless, having AI and a HUD that will alert me to low cylinder pressure seems like it could be valuable in a number of scenarios.
In a tight environment and your O2 gets rolled off? A HUD that alerts you before your ppO2 even begins to drop noticeably seems nice.
Ditto for a situation where your dil gets rolled off.
Last in line on a team, in a low viz environment, maybe with a hood on, so nobody sees your stream of bubbles and you don't hear them? Or maybe scootering, so nobody would see a small trail of bubbles? But, one of your cylinders is gradually losing gas?
Cylinder pressure was good when you assembled your unit, but somewhere between prep and splashing, your O2 got rolled on a bit and your CMF or needle valve let it slowly leak down?
But I digress.... I had a problem. My AI setup saved me from my problem getting worse. I am glad I have it over having regular SPGs.
YMMV.
On the way down, I realized that my BOV was leaking dil into the loop. I could feel it blowing gently into my mouth. I knew the O-ring that surrounds the opening through the barrel into the loop had popped out of its groove. I continued to drop to the bottom as I repeatedly opened and closed the loop, trying to get it to open with the O-ring back in its groove, so it would seal. I could feel the problem with my tongue stuck through the mouthpiece and tried to push the O-ring into place with my tongue as I slowly opened the loop. No luck.
I got to the bottom (157') and parked myself on the sand, with my 2 buddies right there with me, watching me but not really knowing what was going on.
While I was still working on it, knowing I was losing dil, I saw red flash in my NERD display. I focused on it and saw it was telling me that my Dil was down to Critical Pressure (of 50 bar). I knew I was losing dil, but I had no idea I was losing it that fast. Yes, my BOV was plumbed directly to my onboard 3L of dil. Save your breath on that, please. This is not the thread for that.
At that point, I signaled my BOV was broken and thumbed the dive. I shut off my dil at that point, to save some for inflating my wing when I got to the surface, and managed it manually for the rest of the dive. I got back on the boat with very little - but still SOME - dil left.
However, and this is the point, were it not for my AI setup, I very likely would have run out of dil on the bottom before I realized how fast I was losing it. And to be clear, the point is nothing to do with how or why I was losing dil - there are many ways one could be losing it and, even if you know you are, you might not realize how quickly. I was working the problem and would have checked my dil pressure once I got it sorted - which would have been too late, if I had not had a setup to flash a warning right in my face.
According to my downloaded log, it took me 2 minutes to descend to 157' and then I was 4.5 minutes on the bottom trying to fix it before I started back up. The time on the bottom felt more like 1 minute. My dil was TX14/41, so I was as clear-headed as I get. I had plenty of BO gas that I could have plugged into the loop and/or my wing inflator, had I needed to. My buddies were right with me. So, I was never in any serious danger. But, I'm still very glad my NERD and AI setup contributed to saving me from letting my problem get worse for me.
Further notes:
On the surface, I learned of another problem that happens when the BOV/DSV has a leak from the loop to the outside world. I pumped my loop full of O2 on the surface. 2 or 3 breaths later and I couldn't pull a breath from the loop. Pumped it up with O2 again. 2 or 3 breaths later, same thing. I realized that my counterlungs being in the water and my BOV being out of the water meant that hydrostatic pressure was squeezing all the gas out of my loop through the leak in the mouthpiece. As long as I stayed on the surface, the loop was not going to flood, but it did mean I was having to pump my wing pretty much full just to stay there. Had I descended, I believe my loop would have then flooded making me even more negative.
The O-ring in question is one that has a direct counterpart in a regular (Drager/rEvo) DSV, so the same root problem (a leak into the loop through the mouthpiece) could happen with a DSV.
I have decided to listen to "my elders"
D LOL) and change back to a standard DSV. No more BOV, at least for now. So, everyone that had a mild conniption when I said I had my BOV plumbed to onboard dil can relax now. Nobody I've talked to has ever been able to clearly articulate to me why a BOV plumbed to onboard - and DIVED as if there was no BOV at all - is any worse than actually having no BOV. Tell me it's bad? Yes. Plenty of times. Clearly articulate why (if treated as if there were no BOV at all)? Haven't heard it yet. No offense to the several of you who probably are thinking "yes, I did explain clearly why." I'll accept this as a ME problem (not understanding), not a you problem.However, some very experienced CCR divers/instructors whom I greatly respect and who are doing the kinds of dives I want to do (and who I know and have dived with in real life) all dive with no BOV. So, I have tried the BOV and now I'm going to bow to greater experience and go without. If I don't need a BOV, then not having one is SIMPLER than having one and diving as if I don't. And simpler is better. Taking a lesson from Steve Lewis' book, The Six Skills, I don't need it, so I'm not taking it in the water.
I've seen posts from people in the past saying, either, "I never look at my CCR cylinder pressure gauges when I'm in the water" or, "I don't even have pressure gauges on my CCR." This experience has made it clear to me (as if it wasn't already) that I would certainly want to have them. Had I been able to get my BOV to seal up early on, I could have verified that I still had plenty of dil left and then proceeded with my dive plan. Or I could have seen that I got it fixed but lost too much dil and so needed to end the dive early.
Being able to check onboard cylinder pressures seems mandatory, to me. Actually checking them during a dive, also seems like an important thing to do more often than some people claim to. Regardless, having AI and a HUD that will alert me to low cylinder pressure seems like it could be valuable in a number of scenarios.
In a tight environment and your O2 gets rolled off? A HUD that alerts you before your ppO2 even begins to drop noticeably seems nice.
Ditto for a situation where your dil gets rolled off.
Last in line on a team, in a low viz environment, maybe with a hood on, so nobody sees your stream of bubbles and you don't hear them? Or maybe scootering, so nobody would see a small trail of bubbles? But, one of your cylinders is gradually losing gas?
Cylinder pressure was good when you assembled your unit, but somewhere between prep and splashing, your O2 got rolled on a bit and your CMF or needle valve let it slowly leak down?
But I digress.... I had a problem. My AI setup saved me from my problem getting worse. I am glad I have it over having regular SPGs.
YMMV.
