Deep Air VS CCR

[evandroairton]

I don't use air as diluent beyond 45 metres, just because the gas usage is small
For instance, i've never used any gas of my Tx 20/30 BO bottle since it was filled two years ago.
I am just normoxic certified (MOD 2) and helium is not so easy tô find, but i do mantain a Tx dil bottle for my inspirovsky (Inspo classic plus AV1 head) and i usually can take two dives on it, sometimes even a third with an air topoff
Dil flush also would be compromised if air ppo2 is very close to SP (needed once)
I am not a super experienced rebreather diver (no more than +- 150 hours on my units) but don't see a point in not using He on divers deeper than 45 metres on CCR.

 

[runsongas]

i think the better question is which option is riskier

 

[McGlencoe]

I have 0 interest in ever getting a CCR unless it becomes legal to spearfish on them where I'm at.

Spearfishing with a rebreather is illegal in Florida?

 

[RainPilot]

I have done 150' CCR on air, once. Too thick. won't do that again.

Where did you get your t-shirt? I need one of those too.

For instance, i've never used any gas of my Tx 20/30 BO bottle since it was filled two years ago.

I am curious, do you find you get any helium loss in those BO or are you using a cap to seal it off?

 

[100days-a-year]

Spearfishing with a rebreather is illegal in Florida?

I'm always in Federal waters. In the Atlantic, grouper snapper complex species may not be harvested on a RB
I'd also have figure how to get 5 to 7 dives a day out of one. Long dives spearfishing are not that efficient and sharks will be a problem. Doing a long deco hang after essentially chumming up predators is lots less fun than advertised. I normally would have 75+ minutes below 130' per day.

 

[tbone1004]

Spearfishing with a rebreather is illegal in Florida?

in most states it is with the exception of lionfish. It's considered bad sport since the fish don't hear you coming and don't recognize you as a diver without the bubbles.

 

[broncobowsher]

Where did you get your t-shirt? I need one of those too.

No t-shirt. It was one of those things discussed, but not experienced. Had a change of plans, local waters I know well. Benign conditions and it was just a quick bounce without deco. Tried it, didn't like it. Minimal risk, experience gained. Came back with Helium and was much better. There is a difference between OC and CCR at 150 on air. It's one thing to read it, another to experience it. Not a near death experience, just an experience.

So back to the original question. OC vs CCR. OC is defined as air. CCR is not defined, could be trimix (as it should be) or air. My data point is 150'. Done it OC air, CCR air, CCR trimix. OC is fine, CCR air is not good, CCR trimix is fine. My OC trimix was bailout training for CCR and it was fine but it was training and throwing a bunch of stress at me, not going to use that as a data point. I got a CCR to avoid the OC trimix.
If you want data points for deeper you will have to find someone else. I know a few that will do 180' OC air, but they have no trimix nor CCR experience. No valid data there. My 200' is all CCR trimix, never done anything past 150 on air. So I have data for that.

 

[Angelo Farina]

I am not a tech diver. However my recreational CMAS certification is for air down to 50m and deco (not accelerated, all in air) and CC rebreathers with pure oxugen down to 10 meters.
I did approximately half of my 1500 dives at depths beyond 40 meters, with deco. This is considered technical nowadays, it was normal in the seventies and eighties. At those times trimix was terribly expensive and difficult to find, and CC rebreathers were suicide machines.
Air was much safer and easier, and a large number of dives without problens proof that air in OC is a good solution if you do not exceed 50-55m.
Beyond this one should switch to something else.
But I do not understand why recreational limits are now just 40m and no deco.
A dive planned for deco is safer than a dive planned just on the edge of NDL, which can result easily in unplanned deco.

 

[evandroairton]

Where did you get your t-shirt? I need one of those too.



I am curious, do you find you get any helium loss in those BO or are you using a cap to seal it off?

I did checked the contents few time ago, and it was ok! No loss of pressure and reading 20/29 just closed valve. It was a concern sinc helium is a light gás and could scape through tiny fissures. Anyway i may do a new check and see if there is any loss

 

[NAM001]

I enjoy the thread. some one help me on this. what is defined as deep air? Im a bit ignorant on the term. I may know it under other names though. My known understanding of it is it is just air used on deep dives . pushing the PPN2 to the extreem.