ISE and Rebreathers

Achim talking about Rebreathers and why ISE is teaching MCCR primarily

[nosmosisprod]

Hey Achim, I realize this is an older video and my comment is coming late 😂. In full disclosure, I am a GUE diver, but found there were a number of things in the CCR curriculum and thinking I wasn’t sure of so when I thought about buying a JJ, I was deterred because of some of the philosophy. I ultimately did buy an eCCR - but this was kinda a personal decision based on my own philosophy (which I will leave out of this comment). I also see an advantage on mCCR and likely will also get one in the future as another tool. I ultimately did get a unit in a „DIR configuration“ not because I was worried about my running out of gas, but other teammates - because often I am diving in mixed teams (even though I agree it is not ideal, but for me it is a necessary). I will say I also like the elimination of the side-slung bailout and all my dil and bail-out on my back. But all of your points make sense and some of what I have learned (e.g. teammates in CCR have a much different role than in OC and are kinda the last resort if shit has gone completely, and improbably sideways as there are multiple self-reliant solutions you do first).

[ExGEO]

I still dive a draeger dolphin on recreational dives. I was on the Hollis P2 and now I'm on the Meg 15. I don't think I'll ever dive OC again. I did want to make a point about diving with our bailout mounted to the back as well. Typically, we run bailout in sidemount and ccr on the back. Unfortunately, American dive operations are so focused on profit that they neglect safety. If we aborted every dive that was too crowded, we would never dive. So we make a point to carry dual 7liter bottles and 2 or 3 liter bottles for the CCR. This ensures we can dive from the tech boats and still enjoy the dive. If we were going to dive a cave system, that changes everything.

[rabukan]

Hi Achim. I dive a KISS GEM, which is, as you say, a gas extender (PSCR, ) but I use it with twin LP 50s, which is not heavy to begin with. My total weight in a wetsuit is about 43 kg or 86 pounds. It does get heavier, like everything else, when I use a drysuit, by about 5 kg or 10 pounds. It can also be used with a single tank (like AL or steel 80s) but I want the redundancy without having to use multiple stage bottles. There are ways to get more than 3:1, like 5:1+, out of it and you can use trimix in it as well, but it is not advertised this way by KISS as there is no certification if one were to make these adjustments. Still, many GEM technical dive users have learned how to do this. The advantage to this system is as you say, it is about as simple as you can get. There is only one 02 cell and everything else is done manually. If I do make my own adjustments and get say more than 5:1, my 100 cu.ft. tanks now have 500 cu.ft. of gas in them - a lot of gas. Why do you think this is wrong? With a KISS Classic (a great machine) you have at least 1 AL40 as bailout, so you are carrying about the same amount of weight as me, but you have three 02 cells (failure points?) to my one. Thanks!

[zBones]

I think closed circuit is attractive because you only need to bring bail out gas with you encase the unit fails. Since there is no need for switching gasses manually during the dive it removes one of the biggest failure points of technical dives which is breathing the wrong gas. The higher quality units usually have multiple sensors which do tend to go bad, but as long as you care for the unit and replace the sensors -- as well as listening to what the computer is telling you it can be a superior unit to open circuit systems. The biggest issue with closed circuit at depth is respiratory failure because in most cases its your lungs circulating the system; so over exertion and respiratory failure are a real threat; the next is if your computers gives you the wrong information IE everything is fine but you're breathing 2+ Partial Pressure Of Oxygen at 80m or the system goes hypoxic; however in most cases the computer is going to give you some sort of warning. I think if I had the choice I'd still run a closed circuit unit for technical dives provided you're not going 150m+. I'd be really interested in anyone's thoughts and opinions on this.

[AdamJones-vduf]

Achim, your videos are great insight into the thinking and evolving DIR philosophy.
This video made me ask questions though:
Why ISE offers certification on eCCR if the philosophy supports mCCR?
What do you think of a hybrid CCR, where the CMF/COPIS/KISS valve functions throughout the dive, and solenoid acts as a backup under setpoint 0.7 for example in high stress scenario? I think any eCCR could have a leaky valve added on the O2 side.
What do you think of CCR vs pSCR used for deep/long caves? PSCR seems to have a better safety profile, but not as many advantages.
Thanks!

[MortenDallDarmer]

it will be nice with a follow up video showing your Kiss Classic setup :-)

[rustylimestone]

I agree using twin 12L cylinders with a CCR is crazy. But using twin 7L diluent is very nice for deep dives since it means you can have 1 less stage.

[turbor]

Hi Axel, nice video, but I notice your argument on Eccr's do not factor in the probability of the concerns you have with them. Also your concern about an oxygen cell being in the wrong environment in a rebreather is entirely applicable to an mCCR as well.
Cathal