Request for comments on article - mixed OC / CCR teams

[doctormike]

I think you are planning on one more failure than usual.

This is, of course, true. It's just that being on the loop with no bailout freaks me out!

 

[Gareth J]

Nice Article @doctormike

I tend to treat diving with OC buddies as if I was diving solo, with regard to them helping with the CCR itself.

I tend to dive with a wide range of buddies, from newer divers to experienced divers.
The big thing they need to understand is how I am going to donate gas to them, if they have an issue. i.e. from the bailout cylinder and the regulator bungied to the cylinder.

I have learnt through experience, that even experienced OC buddies, who I have dived with regularly, don't really understand what is happening with the rebreather.
I had a 'minor' incident with two regular buddies, the reaction was comical, because the situation was not serious.

We had dropped to a deeper area part way through the dive. The visibility was appalling, keeping track of each other was a challenge (3 of us).
This is not normally an issue. BUT, my mask was leaking, and I was clearing the mask regularly. After getting truly lost (doing a big loop), we decided that we should ascend to a shallower area with better vis'.
As we ascended into better vis', I took the opportunity to check my DIL and O2. My DIL was very low 20 bar - whoops!.
As we swam further, I concluded I was looking at a Darwin Award. So, as I was lugging an Ali80, I shut off the BOV feed from the DIL, disconnected the Manual DIL inflate I was in the process of plugging in the feed from the off board bailout. - No problem.
I had dropped back from the other two with all the re-plumbing. They arrived, and looked confused. Spotted the disconnected hose. So buddy one 'helped', and plugged a hose in.
I looked down, he had plugged the onboard DIL back in, so I disconnected it, and plugged the off board DIL in.
Super - ready to go.
At this point the farce started. Lots of flapping and hand signal. Me giving an OK, then another OK, then another OK. I finally decided the enough was enough and signalled UP.
So we all pulled out DSMB's and fired them off and started to ascend.
We got to 15m and Diver 2's Deep stop warning kicked in, so we all stopped for the deep stop.
Eventually we got to the 6m stop, at this point, they realised that nothing was wrong. We where also some way from the exit point. So ended up swimming at 6m the 200m back to the exit.
The debrief was entertaining.
They fully admitted they had freaked out when I change the hose over. In 10 years of diving with me, they had never seen me switch from normal configuration to off board setup, other than for a preplanned exercise.​

It was an interesting lesson. OC divers don't really understand. Even experienced divers, who had dived with me for 10 years, have listened to the briefing no end of times get confused when you change for the 'normal'!
Also - pay attention to the DIL when mask clearing !!!! ( I know this but with the task loading it was one thing too many).

​

 

[doctormike]

Excellent story, and very helpful.

One of the things that I think is key (and which I mention in the article) is for the OC diver to be able to distinguish between a distracted diver and a conscious but unresponsive diver. As with all diving, communication is key, and your OC buddy has to understand that if you are normally responsive (not panicked, responding to hand signals, etc..), that they are NOT to touch your gear. If they see something dangling, it's fine to point it out, but they should assume that if you are normally responsive, you are much better able to deal with your gear than them.

Your story also points out the utility of telling OC divers about what might happen. If they don't have experience diving with CCR divers, they may just know "rebreathers don't have bubbles". So when you vent on ascent, they may think that there is a problem. Even more so if they see you do a dil flush or an O2 flush at 20 feet, suddenly there are bubbles everywhere! Good to to over that ahead of time, and to make the "I'm OK sign" clearly.

Of course, there are times when a buddy can fix something on your rig in a second that would take you more fumbling, but that should be done on request.

 

[John C. Ratliff]

DoctorMike,

I think it’s a great article. As an OC diver who has never seen a CCR or a SCR, other than reading about them for a while now, it provided some very nice insights. I’ve been an OC diver since 1959, and so have seen a few things over the years.

One thing I did not see in the article is the ability to establish positive buoyancy for the CCR diver on the surface. For instance, it is unknown to me whether a CCR wearing a dry suit (most do, from what I can see), also wears a weight belt or has ditchable weights. OC divers usually either wear a weight belt or have ditchable weights in the BCD, but this is (maybe) not true for CCR divers. This is a fundamental difference which needs to be covered, if true.

Now, about the dilutant flush; in an emergency with an unresponsive diver, I can see the need for this flush. But I have also note the loss of a National Geographic photographer, Wes Skiles, on a rebreather dive where he was found in shallow water unconscious. I’m wondering whether an O2 flush would be more appropriate in these circumstances.
National Geographic Freelance Photographer Wes Skiles Dies

Finally, you talk a lot of “communication,” which is something I have thought about for a long time. I had, in 1972, the idea of building an underwater communication hard-wire system between buddy divers using the buddy line/comm. line system to allow voice communications between two divers. I never got that off the ground, and here we are, fifty years later, still dependent upon hand signals and light flashes. That, to me, doesn’t make sense. CCR divers spend tens of thousands of dollars on breathing systems, and no one applies known technology to make voice communications between divers available! I am amazed that this is not a priority. This would be especially helpful between buddy pairs where one buddy was OC and the other was CCR diving. Why? Why is this so hard for the diving community to make happen?

SeaRat

 

[Marie13]

I know a few CCR divers who would have hard weights attached as part of their rig. There were no dumpable weights.

 

[Gareth J]

DoctorMike,

I think it’s a great article. As an OC diver who has never seen a CCR or a SCR, other than reading about them for a while now, it provided some very nice insights. I’ve been an OC diver since 1959, and so have seen a few things over the years.

One thing I did not see in the article is the ability to establish positive buoyancy for the CCR diver on the surface. For instance, it is unknown to me whether a CCR wearing a dry suit (most do, from what I can see), also wears a weight belt or has ditchable weights. OC divers usually either wear a weight belt or have ditchable weights in the BCD, but this is (maybe) not true for CCR divers. This is a fundamental difference which needs to be covered, if true.

Number 1
- Inflate the wing. MAKE the casualty BUOYANT
- Dropping the weight is never a bad idea, and should be the first thing we all do OC or CCR
- inflate the drysuit - except

the exhaust will start to dump air,
the neck seal may restrict breathing and circulation,
drysuits do not reliably keep the gas
- even with the above, keeping the diver on the surface is paramount​

Number 2
- CLOSE the mouth piece
CCR, are just one big loop with counter lungs, two one way valves, and a scrubber. If you leave the mouth piece open the loop will flood making the diver negatively buoyant.

Number 2 could be number 1 BASICALLY keep the diver on the SURFACE!!!!​

Now, about the dilutant flush; in an emergency with an unresponsive diver, I can see the need for this flush. But I have also note the loss of a National Geographic photographer, Wes Silks, on a rebreather dive where he was found in shallow water unconscious. I’m wondering whether an O2 flush would be more appropriate in these circumstances.
National Geographic Freelance Photographer Wes Skiles Dies

Hypoxic DIL is a whole other story. Which probably means a whole lot of decompression and other complications for those divers involved in the rescue.
Even with a hypoxic mix, say 16%, that is enough O2 to keep you alive (granted there are issues with damaged lung efficiency, inefficient circulation, tissue damage etc which all benefit form 100% O2)
Remember O2 is toxic at depth, below 6m it could bring on an O2 fit.

In CONCLUSION - the DIL is simple, straight forward and safer.​

Finally, you talk a lot of “communication,” which is something I have thought about for a long time. I had, in 1972, the idea of building an underwater communication hard-wire system between buddy divers using the buddy line/comm. line system to allow voice communications between two divers. I never got that off the ground, and here we are, fifty years later, still dependent upon hand signals and light flashes. That, to me, doesn’t make sense. CCR divers spend tens of thousands of dollars on breathing systems, and no one applies known technology to make voice communications between divers available! I am amazed that this is not a priority. This would be especially helpful between buddy pairs where one buddy was OC and the other was CCR diving. Why? Why is this so hard for the diving community to make happen?

SeaRat

In the water.
1. Flush the loop with DIL
2. &/Or switch them to OC bailout if they have a BOV
3. Be aware gas expands and is trapped in the counterlung - you will need to dump this in addition to the wing/drysuit.


On the surface
1. Make the casualty buoyant
2. Ensure mouth piece is Closed
3. Ensure the airway is open on the surface - no mouthpiece
4. Give them O2 once recovered from the water and normal First Aid (CC, AV etc) (Even if they fit, take them off O2 until they stop fitting, then put them back on O2)

FOR YOURSELF
1. Ensure you know how you access gas if you are the buddy, just in case you are OOG
2. Ensure you know what is in the bailout cylinder.
3. BE HAPPY WITH THE SOLUTION before you get in the water.

 

[lermontov]

hi mike
I have to agree with @KenGordon on the article - theres simply way too much information - e.g do OC divers really need to know a schematic ? I bet most ccr divers couldn't write it out .

I guess it depends on what you are trying to with the article /notes. Are you trying to create a checklist that OC divers can understand in a predive brief? As it stands it has the feel of some sort of course like intro to MOD1 for OC divers, I imagine youll get a lot of OC divers likely @johndiver999 who will be put off by mixed teams by reading the article. It really needs to be broken down to ABC this would be a good appendix for CCR divers to take away and print out to give it to their OC buddies

Your summary is pretty good and that would be pretty much all an OC diver who knows very little about ccrs can absorb. Anything beyond that will just create confusion.

 

[doctormike]

DoctorMike,

I think it’s a great article. As an OC diver who has never seen a CCR or a SCR, other than reading about them for a while now, it provided some very nice insights. I’ve been an OC diver since 1959, and so have seen a few things over the years.

So glad that you liked it! Thanks for your kind words

One thing I did not see in the article is the ability to establish positive buoyancy for the CCR diver on the surface. For instance, it is unknown to me whether a CCR wearing a dry suit (most do, from what I can see), also wears a weight belt or has ditchable weights. OC divers usually either wear a weight belt or have ditchable weights in the BCD, but this is (maybe) not true for CCR divers. This is a fundamental difference which needs to be covered, if true.

That's a good point. I do mention this, but I could add another sentence to stress that. CCR divers have some form of BC just like OC divers, usually a wing, so the idea would be to inflate that at the surface. I wouldn't use a dry suit to acheive buoyancy over a wing. And of course, closing the loop is vital, otherwise the rebreather will flood and likely sink.

I don't know any CCR divers that use ditchable weights, but some do add weights when diving in salt water in a dry suit, if the rig is well weighted in fresh water or with less exposure suit buoyancy. I do that with mine (JJ), there are these tubes that you can put lead weights into and take out when you need less ballast. They are perfectly positioned - it's a well designed rebreather.

I guess one reason why ditchable weight isn't common on rebreathers is that losing a weight at depth and having an uncontrolled ascent would be especially dangerous on CCR. Not only would you have the decompression stress, but you could also become hypoxic.

Now, about the dilutant flush; in an emergency with an unresponsive diver, I can see the need for this flush. But I have also note the loss of a National Geographic photographer, Wes Skiles, on a rebreather dive where he was found in shallow water unconscious. I’m wondering whether an O2 flush would be more appropriate in these circumstances.
National Geographic Freelance Photographer Wes Skiles Dies

No, definitely not. Leaving aside hypoxic dil (which as I mention isn't really relevant to this topic), diluent will ALWAYS support life at any point in the dive. The last thing you want is the OC diver trying to figure out whether to add O2 or Dil. Doing an O2 flush at depth can be lethal. If you ever came across an unresponsive CCR diver in less than 20 feet of water (the only depth at which an O2 flush would be safe), you would be better off just taking them to the surface.

Finally, you talk a lot of “communication,” which is something I have thought about for a long time. I had, in 1972, the idea of building an underwater communication hard-wire system between buddy divers using the buddy line/comm. line system to allow voice communications between two divers. I never got that off the ground, and here we are, fifty years later, still dependent upon hand signals and light flashes. That, to me, doesn’t make sense. CCR divers spend tens of thousands of dollars on breathing systems, and no one applies known technology to make voice communications between divers available! I am amazed that this is not a priority. This would be especially helpful between buddy pairs where one buddy was OC and the other was CCR diving. Why? Why is this so hard for the diving community to make happen?

SeaRat

Believe it or not, I bought one of these to try out. Not a fan!


One advantage of rebreathers is that with practice, a buddy team actually CAN talk underwater. I find it hard, because my hearing isn't that great.

 

[doctormike]

hi mike
I have to agree with @KenGordon on the article - theres simply way too much information - e.g do OC divers really need to know a schematic ? I bet most ccr divers couldn't write it out .

Yeah, it's hard to find the right balance. But I think that if you - as an OC diver - really are going to commit to diving with a CCR diver safely, that obligates you to know the basics of how they work, and it shouldn't be TOO simplified.

I do appreciate your reading it and your comments, don't get me wrong. But I don't think that it's a particularly complicated schematic, and none of the other stuff makes sense to an OC diver if they have no idea how CCR's work.

If there was a CCR diver who couldn't write out that schematic (i.e. understand how the rebreather works), they shouldn't have been certified.

I guess it depends on what you are trying to with the article /notes. Are you trying to create a checklist that OC divers can understand in a predive brief? As it stands it has the feel of some sort of course like intro to MOD1 for OC divers, I imagine youll get a lot of OC divers likely @johndiver999 who will be put off by mixed teams by reading the article.

Well, maybe that's good. My goal isn't to convince people to dive in mixed teams. My goal is to help people who are diving in mixed teams for whatever reason, to do it safely. And that does involve a good bit of effort and learning on the part of the OC diver. If that puts them off doing it, that's good, they shouldn't be doing it if they don't want to learn how to do it safely.

It really needs to be broken down to ABC this would be a good appendix for CCR divers to take away and print out to give it to their OC buddies

Your summary is pretty good and that would be pretty much all an OC diver who knows very little about ccrs can absorb. Anything beyond that will just create confusion.

That's a good idea! Maybe I can convert the summary into a printable checklist. Will work on that... thanks!

 

[KevinNM]

DoctorMike,

I think it’s a great article. As an OC diver who has never seen a CCR or a SCR, other than reading about them for a while now, it provided some very nice insights. I’ve been an OC diver since 1959, and so have seen a few things over the years.

One thing I did not see in the article is the ability to establish positive buoyancy for the CCR diver on the surface. For instance, it is unknown to me whether a CCR wearing a dry suit (most do, from what I can see), also wears a weight belt or has ditchable weights. OC divers usually either wear a weight belt or have ditchable weights in the BCD, but this is (maybe) not true for CCR divers. This is a fundamental difference which needs to be covered, if true.

Now, about the dilutant flush; in an emergency with an unresponsive diver, I can see the need for this flush. But I have also note the loss of a National Geographic photographer, Wes Skiles, on a rebreather dive where he was found in shallow water unconscious. I’m wondering whether an O2 flush would be more appropriate in these circumstances.
National Geographic Freelance Photographer Wes Skiles Dies

Finally, you talk a lot of “communication,” which is something I have thought about for a long time. I had, in 1972, the idea of building an underwater communication hard-wire system between buddy divers using the buddy line/comm. line system to allow voice communications between two divers. I never got that off the ground, and here we are, fifty years later, still dependent upon hand signals and light flashes. That, to me, doesn’t make sense. CCR divers spend tens of thousands of dollars on breathing systems, and no one applies known technology to make voice communications between divers available! I am amazed that this is not a priority. This would be especially helpful between buddy pairs where one buddy was OC and the other was CCR diving. Why? Why is this so hard for the diving community to make happen?

SeaRat

FFMs with communications are available, but not inexpensive. FFMs with rebreathers and comms get complex, but not impossible.