Solo diving on a rebreather

[hroark2112]

I know people who won't solo dive OC, even on a 30' deep dive in 80 degree water with 100' of visibility and a pony bottle. My wife is one of those people. The first time I found myself solo, I didn't know what to do. All I could think was "I'm 50' deep with 5' of vis in 52 degree water and there's no one in the water with me....the boat captain is going to ban me from ever diving on his boat again!!" When I got back to the boat, the first thing the captain said was "Hey dummy....that 5 mil has got to be cold down there!!" I didn't die, no one yelled at me, no one really cared.

Now that I've started the pafh to rebreathers, I have realized that as long as I stay within my own limits, I prepare and dive the unit properly and follow my pre-dive checklist, and as long as I dive safely and responsibly, I'll minimize my risks and will be fine whether solo or with a buddy. I've established a few personal practices to follow when diving a rebreather and plan to continue to follow them.

Yes it might kill me. My job, my other favorite sport and my wife are more likely to kill me though.

 

[Drin]

Now that I've started the pafh to rebreathers, I have realized that as long as I stay within my own limits, I prepare and dive the unit properly and follow my pre-dive checklist, and as long as I dive safely and responsibly, I'll minimize my risks and will be fine whether solo or with a buddy.

I personally disagree with your statement, but it is of course your choice. No amount of preparation in the world can prepare you for hypercapnia, and it can occur no matter how carefully you prepare your gear and follow your checklists. It's insidious and you generally won't realize what's happening to you until you've (hopefully) recovered from it.

Unfortunately, sometimes CCR divers DON'T recover from it and then they end up statistics.

This is my personal opinion, of course, and I am by NO mean trying to start an argument. Just suggesting you look a little deeper into hycap and how it can overwhelm you without you even being aware of it happening and perhaps reconsider your decision to solo dive. We don't need any more dead divers.

-Adrian

 

[alewar]

I don't know much about rebreathers, so this question may sound silly, but if hypercapnia is such a risk, why don't they use a CO2 sensor and start ringing an alarm when the partial pressure you are breathing is above a certain level? As I understand, the oxygen level is continuously being sampled, but CO2 isn't?

 

[Drin]

I don't know much about rebreathers, so this question may sound silly, but if hypercapnia is such a risk, why don't they use a CO2 sensor and start ringing an alarm when the partial pressure you are breathing is above a certain level? As I understand, the oxygen level is continuously being sampled, but CO2 isn't?

My understanding is that it's because it's not the partial pressure of gaseous CO2 that makes the big difference. It's the partial pressure of the dissolved CO2 in your bloodstream, and there's no easy non-invasive way to manage that.

-Adrian

 

[ScoobaChef]

I don't know much about rebreathers, so this question may sound silly, but if hypercapnia is such a risk, why don't they use a CO2 sensor and start ringing an alarm when the partial pressure you are breathing is above a certain level? As I understand, the oxygen level is continuously being sampled, but CO2 isn't?

There's still a lot of technical problems with building a CO2 sensor for continuous monitoring that is small enough to fit inside a rebreather, not to mention issues with accuracy and false positives. The inspiration vision uses a temperature sensor in the scrubber to monitor the activity in the sorb, but it's really just a workaround and not a sure way of being sure you aren't getting an excess of CO2.

 

[hroark2112]

I believe one the problems with putting a CO2 sensor in the breathing loop is the humidity. Air from your standard tank is dry air, in a CCR loop if is 90% humid.

---------- Post added February 6th, 2014 at 04:23 PM ----------

I personally disagree with your statement, but it is of course your choice. No amount of preparation in the world can prepare you for hypercapnia, and it can occur no matter how carefully you prepare your gear and follow your checklists. It's insidious and you generally won't realize what's happening to you until you've (hopefully) recovered from it.

Unfortunately, sometimes CCR divers DON'T recover from it and then they end up statistics.

This is my personal opinion, of course, and I am by NO mean trying to start an argument. Just suggesting you look a little deeper into hycap and how it can overwhelm you without you even being aware of it happening and perhaps reconsider your decision to solo dive. We don't need any more dead divers.

-Adrian

I appreciate your opinion and how it was presented

The solo diving I plan to be doing for the foreseeable future is relatively benign, I won't be in caves or wrecks and I will stay away from any heavy current that might make me overbreathe the unit. Is it a bigger risk than strapping on a AL80 and going solo? Yes. That being said, I'm not worried about being a statistic. I'm not ready to curl up & die just yet

 

[TechDeep]

As far as why I didn't bailout when I experienced vertigo and other symptoms of hypercapnia I can't explain. I know they are signs yet for some reason chose to ignore them or was somehow in denial of my situation. /SNIP/...

.....the one good decision I made was the choice of diving with a couple of attentive buddies.

I'm just going to comment on what I consider, as someone new to the RB world, the biggest takeaway from your thread, which I do appreciate you taking the time, and having the guts to post....

While I'm new to RB, I've been a solo OC diver for quite a while now, as I tend to end up in situations where the only buddy available was the insta-buddy variety. I feel in this situation, having the training and gear to go solo is much safer.

But, even thinking about solo on RB is many many hours down the road, so I'll leave that one to others. I see your post as more of a caution against ignoring symptoms, and how deadly denial can be in this circumstance. I mean, if your sorb didn't have the dye, then all the buddies in the world may never have realized how much trouble you were in, no?

 

[Garth]

I personally disagree with your statement, but it is of course your choice. No amount of preparation in the world can prepare you for hypercapnia, and it can occur no matter how carefully you prepare your gear and follow your checklists. It's insidious and you generally won't realize what's happening to you until you've (hopefully) recovered from it.

Unfortunately, sometimes CCR divers DON'T recover from it and then they end up statistics.

This is my personal opinion, of course, and I am by NO mean trying to start an argument. Just suggesting you look a little deeper into hycap and how it can overwhelm you without you even being aware of it happening and perhaps reconsider your decision to solo dive. We don't need any more dead divers.

-Adrian

I tend to disagree with you. The right amount of training may include the steps to never actually suffering from hypercapnia in the first place. This might include proper maintenance, awareness, checklists, following scrubber guidelines, proper assembly, and recognition of dangerous environmental factors such as ridiculous current or other workload considerations.

Many who account for these things never actually have hypercapnia.


Sent from my iPad using Tapatalk

 

[wedivebc]

I'm just going to comment on what I consider, as someone new to the RB world, the biggest takeaway from your thread, which I do appreciate you taking the time, and having the guts to post....

While I'm new to RB, I've been a solo OC diver for quite a while now, as I tend to end up in situations where the only buddy available was the insta-buddy variety. I feel in this situation, having the training and gear to go solo is much safer.

But, even thinking about solo on RB is many many hours down the road, so I'll leave that one to others. I see your post as more of a caution against ignoring symptoms, and how deadly denial can be in this circumstance. I mean, if your sorb didn't have the dye, then all the buddies in the world may never have realized how much trouble you were in, no?

A couple of points here. First the problem I had made me unaware of how grave the situation I was in. CO2 toxity had impaired my ability to even know I was in danger. The indicating sorb is only visible after the dive and the scrubber is removed from the rebreather.

Second point. I am not against solo diving. I do believe solo diving on OC does not really prepare you for dealing with the risks on CCR. I may someday feel the risk of solo diving on CCR is worth it but as yet I don't have enough experience on a rebreathers to feel comfortable with it.

 

[Drin]

I tend to disagree with you.

And you are completely entitled to do that. This is a Coke/Pepsi argument and in most cases no amount of discussion will change anyone's mind. I won't dive solo on my rebreather, and I wish those who want to do so every success in it. That's all there is to it.


-Adrian