59 replies to this topic

[hnladue]

I too will be going that way. But not for a few years. I have had some limited training already on the Inspriation. If you buy the scrubber material in bulk, it's a lot cheaper too. You will get 3 fills out of 1 jug. I don't know what you guys are using. Also a rebreather is a lot easier to carry then doubles!!

[PerroneFord]

That $8k-$14k for a Meg, Ourbouros, Optima, etc. will buy a LOT of trimix fills...

Rebreathers are cool. I like them. But I won't delude myself into thinking that things can and do go wrong. You cannot always breathe the diluent as it is often hypoxic, and the O2 bottle can't even be THOUGHT of as a bailout. For most diving, it's the bailout bottle or nothing. Assuming you can even get to it before you black out of convulse.

All that said, I am going to take a tour in the pool on a KISS sometime in the very near future.

[hnladue]

diluent is often plain old air. And what about that pony bottle you'd be carrying?? My instructor doesn't go in without one.

[PerroneFord]

What rebreathers use air as a diluent? I don't know that much about rebreathers, but I have never seen one that uses just air. Far too much nitrogen for dives of significant depth. I know my instructor uses a 10/60 mix for his diluent.

I try to avoid the term "Pony bottle" as it's too generic. I mentioned the bailout bottle in my last post. I suspect that's what you're referring to. The ability to go to open circuit. There's a problem there as well depending in the dive profile. What do you put in it? Bottom mix? Mid-water mix? Assume your profile is to 240ft. Do you bailout to air? Heliox? I think if I had the choice I'd be filling with 18/55 or something thereabouts.

Do deep rebreather divers carry two bailouts? And how do you finish deco? I can't imagine the obligation after sitting in 200-300ft of water for 2 hours, and then losing the unit. Buddy breathing is a BEAR.

Lots of stuff to consider.

[Diverbrian]

What rebreathers use air as a diluent? I don't know that much about rebreathers, but I have never seen one that uses just air. Far too much nitrogen for dives of significant depth. I know my instructor uses a 10/60 mix for his diluent.

I try to avoid the term "Pony bottle" as it's too generic. I mentioned the bailout bottle in my last post. I suspect that's what you're referring to. The ability to go to open circuit. There's a problem there as well depending in the dive profile. What do you put in it? Bottom mix? Mid-water mix? Assume your profile is to 240ft. Do you bailout to air? Heliox? I think if I had the choice I'd be filling with 18/55 or something thereabouts.

Do deep rebreather divers carry two bailouts? And how do you finish deco? I can't imagine the obligation after sitting in 200-300ft of water for 2 hours, and then losing the unit. Buddy breathing is a BEAR.

Lots of stuff to consider.

Diluent is dependent on the depth that you plan to dive. In my case, I may use a normoxic tri-mix (same as I currently carry in my doubles). For the first several operating hours, I would be using air as a diluent though. The bouancy control is a little different on these things and takes some getting used to. In some ways is like learning to dive all over again. Bottom line is that Diluent is bottom mix and the unit mixes in the O2 to make it richer and accomplish the constant PO2.

The deco obligation wouldn't be any worse than I pick up on a non-constant PO2 system (OC doubles) and may be better than that in reality. Also, you don't do any more deco than you are carrying deco gas for in the event of the type of emergency that you refer to.

I don't dive them yet, so others can speak with more knowledge. That is my basic understanding though.

[hnladue]

What rebreathers use air as a diluent? I don't know that much about rebreathers, but I have never seen one that uses just air. Far too much nitrogen for dives of significant depth. I know my instructor uses a 10/60 mix for his diluent.

I try to avoid the term "Pony bottle" as it's too generic. I mentioned the bailout bottle in my last post. I suspect that's what you're referring to. The ability to go to open circuit. There's a problem there as well depending in the dive profile. What do you put in it? Bottom mix? Mid-water mix? Assume your profile is to 240ft. Do you bailout to air? Heliox? I think if I had the choice I'd be filling with 18/55 or something thereabouts.

Do deep rebreather divers carry two bailouts? And how do you finish deco? I can't imagine the obligation after sitting in 200-300ft of water for 2 hours, and then losing the unit. Buddy breathing is a BEAR.

Lots of stuff to consider.

PerroneFord- Don't think so deep!! My trainer likes to keep everything above 150ft. He has a 40cft pony bottle that usually has air in it. I think he usually has air in the unit too but may put nitrox in sometimes.

Same as Brian said-- I don't dive these yet... so I'm still a bit unfamilar. I may try one out next summer if my trainer has time.

We can think about going deeper later, but just keep it realistic for now. I can't see anyone buying a rebreather and autmatically jumping into 800ft dives.

[PerroneFord]

Please understand that I live 30 minutes from the Wakulla Karst Plain. ALL the caves near me are over 200ft deep, and most are over 300. Once you branch out to places and hour or two away, they move to 80-150ft deep.

So what may be hugely unrealistic to you, is the norm here. Even on my training dives for Nitrox, my instructor was on his KISS. With 10/60 diluent and oxygen. And we made sure to check on him regularly. We were playing from 40-100ft at Blue Grotto and Troy Springs.

[Diverbrian]

Please understand that I live 30 minutes from the Wakulla Karst Plain. ALL the caves near me are over 200ft deep, and most are over 300. Once you branch out to places and hour or two away, they move to 80-150ft deep.

So what may be hugely unrealistic to you, is the norm here. Even on my training dives for Nitrox, my instructor was on his KISS. With 10/60 diluent and oxygen. And we made sure to check on him regularly. We were playing from 40-100ft at Blue Grotto and Troy Springs.

My dive buddy wasn't telling you that this is unrealistic up here. I know of a wreck in Lake Michigan that was visited by two divers using Inspiration CCR's down to 380 ft. I dive wrecks on OC up here that are at 200 ft., but only if the weather is right for the boat trip!

But, there are different classes for diving full tri-mix on CCR even if you dive full mix on OC for a reason. This is not a race. You will get there if you want to. As a matter of fact, I am likely not taking my full tri-mix course until after I get a rebreather and I will have to spend time and money in Brockville, ONT to use a different instructor than the one conducting my first CCR course as he is not certified to those depths on a rebreather himself.

By the time that you get to the point of using a 10/60 mix for a diluent, I would think that most of your questions will be answered that you are asking here. You'll get into those caves, but it will be a matter of time whether one goes with OC or CCR.

[ScubaDadMiami]

There are a lot more options open to the diver than one would think in these situations:

You can fly the unit automatically AFTER YOU KNOW WHAT YOU ARE DOING.

You can fly the unit manually, adding either oxygen or diluent so that you can stay within the proper PPO2 even if you have a hypoxic mix for diluent once you move up to the shallows.

Even if you have complete oxygen failure, you can use the diluent in the deeper zones until that become hypoxic. Then, you can switch over to another source such as a deco bottle.

If the oxygen solenoid sticks open, you can operate manually, shutting down the oxygen valve, flushing with diluent to lower the PPO2.

You can extend gas by driving the unit like a semi closed rebreather. Add some gas, shut the valve, breath a few breaths, repeat. You can also exhale gas into the water, which will waste some but still be way more efficient than going completely open circuit.

You can plug in your bailout or other external bottle to the unit if you are having problems with one of the onboard gas supplies such as if there is a first stage regulator failure.

You can turn the unit to open circuit, breathing the 27 cubic foot tanks (at 2640 psi), then switch to your bailout bottle until you get to stages or to the shallows, where you can switch to deco bottles.

You can always bail out to open circuit bottles.

So long as you monitor your gauges and follow what you have been taught in training, there are a lot more options than you might think.

Edited by ScubaDadMiami, 01 December 2005 - 12:46 PM.

[PerroneFord]

Diverbrian,

Please understand I am not trying to get in those caves. I am not a "cave diver". My interest lies in wreck diving. However, unlike most people, the deep diving is all at home. People travel far and wide to dive deep caves. I have to travel because I CAN'T dive them!

But I'm not complaining. I live in diving mecca. And the better diver I become, the closer to home I can dive!

[gcbryan]

PerroneFord, I don't get your point. You say that diluent couldn't be air when diluent can actually be anything that you could use in OC and of course you can use air in OC. Then you start talking about it being inappropriate for your local caves (who said it was appropriate for your local caves?) but then you say that you don't dive your local caves anyway.

I'm not trying to pick on you I'm just trying to figure out what your point is.

[PerroneFord]

PerroneFord, I don't get your point. You say that diluent couldn't be air when diluent can actually be anything that you could use in OC and of course you can use air in OC. Then you start talking about it being inappropriate for your local caves (who said it was appropriate for your local caves?) but then you say that you don't dive your local caves anyway.

I'm not trying to pick on you I'm just trying to figure out what your point is.

Ok, let me see if I can clarify.

1. I am not a rebreather diver.
2. The only people I have seen use rebreathers did so with hypoxic trimix and oxygen.
3. The use of air as diluent seemed strange given how much nitrogen there was.
4. I was advised not to think about just deep diving, and was merely pointing out that the diving near me is deep so I think about it often. I guess it's like saying you live next to a cenote but have to drive 2 hours to open water because you aren't cave certified. Sometimes I'd love to be able to run down the road a bit and just dive. But in order to do that, I have to further my diving a LOT.

I wasn't trying to make any significant point here. I was just trying to bounce some stuff around and hopefully learn something. And I have. Sorry for any confusion.

[blacklatexozdiver]

I know stuff-all about rebreather diving but I had a look on Ebay and found a seller selling former Russian navy rebreathers. Has anyone tried them?

[Capn Jack]

I know stuff-all about rebreather diving but I had a look on Ebay and found a seller selling former Russian navy rebreathers. Has anyone tried them?

I have zero experience with rebreathers, but I'm thinking you'll have a major problem with support, parts and manuals.

[blacklatexozdiver]

I know stuff-all about rebreather diving but I had a look on Ebay and found a seller selling former Russian navy rebreathers. Has anyone tried them?

I have zero experience with rebreathers, but I'm thinking you'll have a major problem with support, parts and manuals.

I hear ya! I'd wanna be absolutely sure I could get parts if I was going to buy any. I'm interested in whether the Russian stuff actually works.