Skipping open circuit and going straight to CCR

[takez0]

This is my first post here. I've learned a ton on this board and I'm grateful for the insights you all provide.

I'm getting into technical diving and I'd like to jump straight into a CCR. Does the group see any benefit or hindrance in skipping open circuit tech training costs and equipment costs and going straight into a CCR? CCR's are obviously an investment. I'd rather not spend money on a new BCD, manifold, tanks, etc., that would only be used specifically for dual-tank open circuit, considering I know where I want to end up already. Let me know your thoughts or if you think this is missed training opportunity.

 

[Celt]

You are discussing plans for what bike for riding the Tour deFrance to someone who is looking for there first bicycle. So incredibly far out of scope of the question it doesn't make sense to even suggest it. We still need to install the training wheels on the first bike.

I don't normally go out and say this. But suggesting to someone who is thinking of getting into a rebreather to just get a second as the bail out option has got to be one of (if not the top) stupidest things ever suggested here. A bailout rebreather is a super specific tool for super specific dives. There are a LOT of stages between running a simple bailout for non-decompression dives and being anywhere a bail out rebreather would be a benefit more than a libality. MOD 3 is the last of the official rebreather classes. It is several more layers deep before the BOB is the right tool.

Celt, at this point I have to ask what rebreather experience do you have? It doesn't sound like you have much if any.

I have no experience on a rebreather, I was asking, why would someone bother with OC, if they intended to only use a rebreather. Maybe you can explain why someone couldn’t use a rebreather to NDL for training and experience and then use a similar rebreather for bailout. Isn’t the liberty rebreather designed for that. It wasn’t long ago people said rebreathers are only for long and deep dives but today people are using them for all their diving. Things move on.

 

[formernuke]

I have no experience on a rebreather, I was asking, why would someone bother with OC, if they intended to only use a rebreather. Maybe you can explain why someone couldn’t use a rebreather to NDL for training and experience and then use a similar rebreather for bailout. Isn’t the liberty rebreather designed for that. It wasn’t long ago people said rebreathers are only for long and deep dives but today people are using them for all their diving. Things move on.

Above my level but using 2 ccr's would be incredibly complex. It is done only when dive would exceed scrubber time, in my case 4hrs. That's a long time under for one dive.

When diving ccr you carry enough OC gas to safely reach the surface in the event of rebreather failure. For me that's max of one deep bailout and one deco bailout if I'm doing deco dives. If no deco then just the one bailout.

 

[Celt]

Above my level but using 2 ccr's would be incredibly complex. It is done only when dive would exceed scrubber time, in my case 4hrs. That's a long time under for one dive.

When diving ccr you carry enough OC gas to safely reach the surface in the event of rebreather failure. For me that's max of one deep bailout and one deco bailout if I'm doing deco dives. If no deco then just the one bailout.

Thanks, so would a liberty bailout rebreather eliminate both OC tanks and also track your dive making the switch in the case of bailout very simple.

 

[oya]

This is a conversation that was pretty big for a while a few years ago. And one I struggled with because I felt that I could make a persuasive argument either way, but something still bothered me about it. It all felt wrong an unclear somehow.

Then, at a rebreather forum at DEMA one year, maybe 10 years ago, this question was put to a panel of CCR manufacturers. The founder of ISC, rEvo, AP, Dive Rite, etc all sitting there. They mostly gave some version of, "OC experience is important, but I suppose, with the right person, it could be done." Basically it seemed that everyone up there was equivocating as much as I was.

Except for Lamar Hires from Dive Rite. When the question reached him, in his laconic, North-Florida way, he simply said, "If things go bad and you have to bail-out you're on open circuit. You better be real good on open circuit."

That was it. That was his whole answer.

And just like that I finally fell on one side of the fence over the other.

Learn on OC first.

Go to rebreather when it's time.

 

[grantmac]

The question (for me) is do you absolutely need OC trimix experience to become a safe technical rebreather diver.
Staged decompression and bottle rotation doesn't require spending time deeper than 35-40m on OC which is easily AN/DP territory. Likewise regularly practicing bail-out procedures seems a lot more likely when it's an air fill and not hundred of dollars in trimix.

There seems to be a debate about whether the safest rebreather is the one you use only when absolutely necessary vs the one you use so often that it's completely second nature.
I am not a rebreather diver (yet) but my exposure to complex equipment that can kill you tells me that currency and familiarity leads to a lot more safety than avoidance.

 

[formernuke]

Thanks, so would a liberty bailout rebreather eliminate both OC tanks and also track your dive making the switch in the case of bailout very simple.

Not sure, way above my current level.

I imagine that switching car's would not be easy plus if I do it I would still carry oc bailout though

 

[Wibble]

As a rebreather diver, I can assure you that they're complex things with lots of things that must be constantly monitored and they can -- and do -- go wrong in an instant.

The big tip to anyone moving to a rebreather is you stick with the rebreather. Lots of time and effort and pretty much only diving that rebreather. It takes a while to become good at it and needs undivided attention to do it. That old adage, the more you practice the better you get.

It is easy to think that the solution to bailing out is a bailout rebreather. The problem is you're doubling the workload and you've got to be thinking about two things at the same time as you must keep the bailout rebreather prepared for an immediate switchover. They're like a cat: lovely in your lap and then suddenly they'll shred your face.

Again; bailing out to OC is like wearing your old comfy shoes. Really simple, only needs you to breathe and periodically check the gas.

 

[J-Vo]

...do you absolutely need OC trimix...

No, but competency with 2 deco bottles and a stage/travel will greatly simplify your breather training. Most people don't get there until TRIMIX. Most AN/DP classes don't even teach two deco gasses. How do you stress the importance of switch protocol with only one deco gas?

 

[gordonscuba]

I think most tec-level backmounted rebreather should be able to bolt onto any standard backplate and webbing. Most rebreather wings can also be used with a backmounted twinset, so one reasonable path is to start diving OC tec with a twinset and a wing like this one:

CCR XT Wing - Dive Rite

The BC 5500 CCR XT adjustable lift wing is designed for the O2ptima eCCR or any rebreather diver looking for maximum durability, versatile options, and the ability to streamline their hoses and wing for in-water efficiency.

www.diverite.com

Then, when you get your ccr, don't buy an extra BP/W with it, just keep using your old reliable BP/W setup and bolt on a ccr instead of a twinset on the days you are diving closed circuit.

The hardware you need to convert an existing pair of tanks into a twinset is not super expensive. If you already have right and left handed tank valves (like for sidemount), a crossbar with an isolator is about $100 and a set of twinning cylinder bands with bolts about $180.

 

[grantmac]

No, but competency with 2 deco bottles and a stage/travel will greatly simplify your breather training. Most people don't get there until TRIMIX. Most AN/DP classes don't even teach two deco gasses. How do you stress the importance of switch protocol with only one deco gas?

So do some professional development or take a course like TDI ER?
Seems like a situation where someone who is very comfortable in sidemount would have a leg up as well.