Request for comments on article - mixed OC / CCR teams

[doctormike]

We had a discussion a few years ago about this topic, and I have given a lecture on it at Beneath the Sea. I finally got around to putting this in article form, and adding some images.

Here's a draft of the article, if anyone is interested in taking a look and letting me know their thoughts. Anything major missing that should be included? Anything inappropriate? Any better way of explaining things?

Thanks very much!

 

[Jack Hammer]

I think it's a nice article that covers the basics and general concepts for the layperson rather well.

 

[doctormike]

I think it's a nice article that covers the basics and general concepts for the layperson rather well.

Thanks so much!

 

[irycio]

Thanks for that work! I may soon find myself in this position since my regular buddy is doing a MOD1 course, so I've found the article of great use .

One possible question which I would like to understand is about position of the members in the mixed team. We usually dive in a line (one behind another) and with everyone on OC it works just fine using the light to communicate, since you can easily notice your buddy's light disappearing or waving all over the place. Now, with CCR's issues such as O2 levels surging or dropping you may not notice anything until the problem is advanced, so it's good to have a possibility of regularly staring in your buddy's face or their handset.
Does that imply that for a mixed team the best positioning would be next to each other, instead of one in front of the other?

Cheer.s

 

[doctormike]

Thanks for that work! I may soon find myself in this position since my regular buddy is doing a MOD1 course, so I've found the article of great use .

One possible question which I would like to understand is about position of the members in the mixed team. We usually dive in a line (one behind another) and with everyone on OC it works just fine using the light to communicate, since you can easily notice your buddy's light disappearing or waving all over the place. Now, with CCR's issues such as O2 levels surging or dropping you may not notice anything until the problem is advanced, so it's good to have a possibility of regularly staring in your buddy's face or their handset.
Does that imply that for a mixed team the best positioning would be next to each other, instead of one in front of the other?

Cheer.s

Thanks! I understand your point.

I think that I'm concerned about implying that the OC diver has the responsibility of monitoring the CCR diver's PO2. That really can't be the case, the task loading might impact negatively on the OC diver's safety. On the other hand, when there is an obvious alert that seems to be being missed, it's reasonable for the OC diver to at least know enough to tell the CCR diver "hey, is that OK?".

The best example of this is this terrific video that I use in the lecture, with permission:

 

[Marie13]

I will read this later as I’m diving with buddies on CCR these days. Do have to relate a funny story. Went diving with a buddy newly CCR certified in January. I was the first OC buddy since he got CCR certified. He kept hearing a gurgle, thought he had water in his loop, and ended the dive.

Turned out there was no water in his loop and the gurgling he heard was my bubbles.

 

[doctormike]

I will read this later as I’m diving with buddies on CCR these days. Do have to relate a funny story. Went diving with a buddy newly CCR certified in January. I was the first OC buddy since he got CCR certified. He kept hearing a gurgle, thought he had water in his loop, and ended the dive.

Turned out there was no water in his loop and the gurgling he heard was my bubbles.

Hilarious! You do get used to the silence...

 

[wnissen]

This article is relevant to me as I am an open-circuit diver who has a rebreather buddy. His pre-dive brief to us was mainly the importance of the diver-surface lever being closed if his mouthpiece ever become dislodged, which is well covered by your document. One risk we ran into was the extensive nature of the pre-dive checklist. My buddy was slower getting ready than those of us who didn't need to do a pre-breathe and ended up skipping part of his checklist to catch up! Thankfully, this did not result in an incident. After we found out what happened we impressed on him the importance of doing the whole thing even if it was slower. But that's an inherent part of the CCR being set up once for a two hour dive vs. two one-hour open circuit dives.

The reasoning behind using diluent as the gas to flush the loop certainly makes sense, I feel comfortable locating that valve in an emergency. However, I'm concerned that the overall complexity is extremely high for open-circuit divers who don't have a formal or even intuitive grasp of rebreathers. To a certain extent this is mitigated by the rebreather diver likely only having one type, so there won't be as many branches in the decision tree, but it's still a lot. For example, if a CCR diver is struggling to manage their airspaces on ascent and descent, I have no hope of finding and manipulating all that in an emergency. Whereas with a non-responsive OC diver I am more or less working on equipment that mirrors my own. I completed PADI rescue a year and a half ago and am moderately confident of my ability to handle an open-circuit incident, for your reference. I look forward to the finished article, obviously I have a lot to learn about my buddy's equipment. Thanks for posting.

 

[Compressor]

Very nice article. Wish I knew more about CCRs so I could give suggestions but since I am naive in that aspect, I cannot.

 

[doctormike]

This article is relevant to me as I am an open-circuit diver who has a rebreather buddy. His pre-dive brief to us was mainly the importance of the diver-surface lever being closed if his mouthpiece ever become dislodged, which is well covered by your document. One risk we ran into was the extensive nature of the pre-dive checklist. My buddy was slower getting ready than those of us who didn't need to do a pre-breathe and ended up skipping part of his checklist to catch up! Thankfully, this did not result in an incident. After we found out what happened we impressed on him the importance of doing the whole thing even if it was slower. But that's an inherent part of the CCR being set up once for a two hour dive vs. two one-hour open circuit dives.

The reasoning behind using diluent as the gas to flush the loop certainly makes sense, I feel comfortable locating that valve in an emergency. However, I'm concerned that the overall complexity is extremely high for open-circuit divers who don't have a formal or even intuitive grasp of rebreathers. To a certain extent this is mitigated by the rebreather diver likely only having one type, so there won't be as many branches in the decision tree, but it's still a lot. For example, if a CCR diver is struggling to manage their airspaces on ascent and descent, I have no hope of finding and manipulating all that in an emergency. Whereas with a non-responsive OC diver I am more or less working on equipment that mirrors my own. I completed PADI rescue a year and a half ago and am moderately confident of my ability to handle an open-circuit incident, for your reference. I look forward to the finished article, obviously I have a lot to learn about my buddy's equipment. Thanks for posting.

Sure, glad you liked it! Of course, there is no justification for skipping part of your regular checklist, ever. Not sure what the issue was there, but most mixed teams work out some sort of timing adjustment so that everyone is ready to splash around the same time.

You are right - while there are many different types of rebreathers, the OC diver is most commonly going to be diving with one person, so all that matters is the details of that particular rebreather. They don't have to learn about a wide range of configurations.

The main thing would be to focus on the few things that actually would matter in an emergency. If you know how to hold the loop in place, how to do a dil flush and how to vent on ascent, that's plenty. It's also nice to know that if you see an alert light, make sure that your buddy has seen it it too.