CCR trained… still diving OC?

[Edwaty]

Hi,

I’m considering getting trained on a CCR (currently CMAS 2* with some nitrox training). I’ve already tried one (AP Diving) for an hour or so in shallow water and loved the experience. I’ve also read quite a lot about it and find it definitely interesting.

And now I’m wondering: considering the huge benefits of CCR diving (duration, silence, optimized deco, limited gas refill…) do you still dive on OC?
Excepted the cost, and maybe availability / travel constraints of using a CCR, I can’t see where it may be more interesting to dive on OC (or maybe just if the planned dive is short and shallow and all the OC stuff is already ready on the boat).

And I can’t even see why we would still dive doubles or OC trimix, both having, in my newbie opinion, absolutely no advantage compared to a rebreather.

Anyone experienced to explain this a little bit?

Last thought: I suppose that if you dive trimix CCR you will also need trimix OC to use the bailouts? So even if you never dive OC, you’ll still need an equivalent OC training?

Thanks

 

[AJ]

And I can’t even see why we would still dive doubles or OC trimix, both having, in my newbie opinion, absolutely no advantage compared to a rebreather.


Last thought: I suppose that if you dive trimix CCR you will also need trimix OC to use the bailouts? So even if you never dive OC, you’ll still need an equivalent OC training?

I'am in the same boat as you. When I switch I will be selling my OC doubles, maybe single OC set up too. I will keep my sidemount setup for OC.

Bailout is not OC Trimix. So no, you don't need Trimix certification to do Trimix CCR. You will learn to bailout to OC during your CCR course.

 

[grantctobin]

Hi,

I’m considering getting trained on a CCR (currently CMAS 2* with some nitrox training). I’ve already tried one (AP Diving) for an hour or so in shallow water and loved the experience. I’ve also read quite a lot about it and find it definitely interesting.

And now I’m wondering: considering the huge benefits of CCR diving (duration, silence, optimized deco, limited gas refill…) do you still dive on OC?
Excepted the cost, and maybe availability / travel constraints of using a CCR, I can’t see where it may be more interesting to dive on OC (or maybe just if the planned dive is short and shallow and all the OC stuff is already ready on the boat).

And I can’t even see why we would still dive doubles or OC trimix, both having, in my newbie opinion, absolutely no advantage compared to a rebreather.

Anyone experienced to explain this a little bit?

Last thought: I suppose that if you dive trimix CCR you will also need trimix OC to use the bailouts? So even if you never dive OC, you’ll still need an equivalent OC training?

Thanks

There’s a ton of value coming from an OC (at minimum Tech1) mix background, especially when stuff hits the fan. Unfortunately, it’s not a requirement for most agencies. The number of OC bailouts required at minimum per standards over the course of MOD1 through MOD3 is not very high.

 

[PfcAJ]

I still use my OC doubles for stuff shallower than 120ft or so. The advantage is that if it breaks it doesn't put you to sleep. Setup and teardown is easier, too.

 

[broncobowsher]

5 years ago I had a strong interest in CCR. Was doing all the research I could. Much like it looks like you are now. Was starting into my tech path. AN/DP via TDI. Never made it to Trimix, fairly steep expense for the learning curve. Knowing that a CCR was in my future I decided to start there. I still think that was a good move.

Almost 4 years ago I got a rebreather. It is a rEvo just for reference. Clicked off the check boxes of what I wanted to do with it and is locally heavily supported. After the first year of just getting back to being proficient at diving (I don't get to dive every weekend, 1 weekend a month is what I consider normal) I took the next class. Normoxic trimix. First time I had Helium underwater.

I kept and still use all my regulators. But none of the rest of the tech stuff. Recently sold it off to someone starting the path. All I dive is CCR even in recreational conditions. But most of my diving is local (I drive, not fly). I do fly with it. A bit of a pain but worth it. Takes some logistical planning. But that is one of the reasons I got a rEvo, it does fit as a carry on.

I couldn't ditch all my old gear. I still have a single tank setup. It is for basic dives (unstick the anchor when boating on a non-dive trip, changing a friends pool light, etc.) Really never use it but too handy to not have it.

FYI, your SAC rate tends to go to crap once you start a CCR. You have an unlimited gas supply. Full lung cycles are good on CCR. This tends to throw your OC air consumption out the window. Mine wasn't good to start with.
I also can't stand how noisy OC diving is now. Something that is also noticed when going back to OC, the buffeting from the exhaust bubbles. You really don't notice how much buffeting your head takes until you switch from CCR back to OC.

 

[NothingClever]

I was diving from a LOB with an Englishman in the Red Sea last year. While he was doing ST recreational dives, I was doing OC technical dives with some Lebanese and French dive buddies. He took notice of my AL80 twinset rig on the first day and smiled in a somewhat curious way but I didn’t think much of it (thinking he was scoffing at technical diving, my equipment configuration, etc).

On a surface interval a day later we sat next to each other for lunch. I’m extroverted so, of course, I didn’t shy away from the opportunity to chat with the gentlemen. After tugging on some threads, I came to find out he was a very experienced civilian CCR diver who had been teamed with and was sponsored by the Royal Navy to conduct WW II artefact recovery along key parts of the North Atlantic for some national museums in England. He was very understated in his accomplishments.

I asked him what he had been smiling about and he commented on the enviable simplicity and universal accessibility of OC diving. He said it was nice to see an American, a Lebanese and a Frenchmen jumping in together with simple rehearsals, a common “dive language” and similar procedures for contingencies. He further stated that while CCR diving gave him flexibility he never felt inclined to take his rig on vacation based on his experiences with it for his recovery work. He said he he would go through a build twice before leaving the dock, get three hours out to sea and still have a failure. He concluded that while CCR was great, it was simply too costly to pursue for fun diving and that he preferred the simple repairability of OC diving.

I don’t share that to try to steer others away from CCR diving but offer it as an interesting and contrasting perspective amongst the more easily-found legion of CCR devotees. I’m sure I’ll learn to dive CCR someday but I’m not in the hurry I used to think was necessary to become a proficient diver.

 

[Wibble]

Diving CCR is more-or-less a one way street. CCR's massively more complex and requires a completely different mindset to Open Circuit. For all of that it's a wonderful experience with many benefits.

Diving without real gas limits is my favourite; I got slightly stuck in a wreck a while back and my "captain" went off the rails, screaming at me that you're going to drown... Then logic kicked in and told him to shut up as there's no hard limits like there is with Open Circuit where your minimum gas is a hard limit (OK, your've some reserves). You can guzzle as much breath as you want; no limits and no wasted gas as it's recycled.

Diving with warm, moist gas is nice; no sore throat. No bubbles means the fish aren't bothered with you.

When you're diving deeper -- say 60m/200' -- the cost is minimal; literally a few bucks extra for breathing a rich helium mix. On open circuit it's hundreds of dollars. Virtually every dive I do, even shallower ones, I'm diving with helium.

Better still if the dive's changed due to weather/whatever from 60m to 30m, you don't care. It's just good to get away from the OC divers crying on the boat.

In essence, every dive's the same (within reason). The main difference is you take different bailout bottles with you. Up to 40m/130' I'll use a single 7 litre cylinder of 32%. Up to 50m/170' I'll use a pair of ali7s, one with 21/35, one with 60%. Over 50m/170' I'll be using a pair of ali80s with 18/45 and 60% (both blown with "cave" fills).

Bailouts aren't used on the dive (except for a quick bailout test on the bottom).


I'd only go for OC if other kit is better; sidemount with smaller cylinders if there's restrictions around or for simplicity on a shallow dive. Would rather use the rebreather though


Now the important thing: going to a rebreather is a BIG commitment. This ain't "doing yer PADI"; this is a serious amount of learning and re-learning how to dive. You MUST keep up to date and dived up lest it will kill you. They're like that; more effort, more fettling, more practice. But lovely to dive.

 

[Degenerate]

I sold my OC doubles when I finished my CCR training.
I still love diving my OC single setup for rec dives every now and then, and will continue to do so.
Bringing my CCR to the local quarry with a max depth of 12m does not make sense to me, unless the plan is doing drills with it.

 

[rddvet]

I do most of my dives on CCR, but all my dives are cave dives. Sadly I haven't dove OC sidemount in over 2 years now (wonder how my regs will be when I go back) but still dive BM doubles regularly to stay proficient or for quick easy dives. If I have to carry a stage or two, I'm diving CCR. You still need the stages since you bailout to OC, but at least I can spend way more time in the areas I'm diving to.

 

[broncobowsher]

I'll add a little more now that I have had time to think about more details...

The logistics challenges tend to be sourcing sorb, pure O2, and Helium. Helium issues are the same as any Trimix dive, so not that different. O2 might be an issue as you want 100% and not a banked Nitrox blend. Again not generally much of an issue. You may not get a full fill if they are not running a booster, but you can get enough. Sorb is the biggest challenge, at least for me. Going places that support rebreathers it is fine, they stock it. But often you are having to deal with it yourself.

I did a U352 dive a couple years ago and a friend was doing a big motorhome road trip. Gave him a keg, met him there, used what I needed, he brought the keg back. It was a little dusty after 4 months on the road but still usable. Another was shipping empty tanks in the mail ahead of time so they would be full in the morning without having to arrive early the day before. Enjoy the wreck, be first into the water, and one of the last to leave. Hang out watching the chit show on the hang line with zero concerns. There were others diving doubles on the recreational boat, because that is how they typically dive. I got to see more of the wreck than all the single tank divers who were there for little more than a bounce dive. The enjoyability factor of having a rebreather on that type of recreational dive was worth the logistical issues. I want to get back to the Oriskany on CCR now. That on OC was little more than a bounce dive. So much to see but so little gas to stay there for the time.

A trip to Truk the rebreather was also great to have CCR. There was so little helium around that only the rebreather divers got it. One guy showed up and dove OC and generally hung with us rebreathers on all but the deepest stuff. To be fair, he did have a rebreather that did not come back from service in time for the trip. His O2 bill was huge just for the deco gas. Somewhere between double and triple our rebreather costs. If Helium had been available for the OC divers, and he used following the CCR dives we did, it would have cost as much as a CCR and probably some of the training to go with it.

The no big deal if the plans change is another huge bonus. Generally the worst thing is slightly less than "ideal" bailout. But you rarely will ever mix an ideal bailout anyway. My bailout is generally one of 2 setups. My shallow and my deep. It has been full for a couple of years now. And I plan to keep it that way for a few more.