Recreational rebreathers - what is holding them back?

[silent running]

Hello pescador775, fwiw the manual for the Prism is quite short, it's under 25 pages as the unit itself is very simple compared to most other CCRs. As for my point above about awareness, I think that RB's initially require a lot more of it and a lot more follow through than OC, but once you get a grip on the physiologic priciples involved and the mechanics of your unit, everything get's much easier. Unless you are doing a lot of serious deco diving, CCRs are not so demanding that you can't enjoy the dive. In fact that's why I bought mine. I knew I was missing something by being so noisy and visible underwater and that I would enjoy diving more if I could blend in better with the wildlife. And boy did I. I spend about 45 minutes at the begining of the dive day and other than topping off my tanks once in the middle of the dive day, I can do 6 plus hrs of worry free diving. Once the diving has begun we both have to check gas supply and computer. For me there is the extra and oh so demanding task of looking at my heads up display and occaisonally verifying my PO2 with the secondary gage clipped to my harness. Believe me it's not so hard. Considering the wildlife encounters I've had since I started diving rebreathers, I think it's more than worth the small extra effort everyday. I see things OC guys never will. The main investment of time and effort comes initially during training and learning about which unit is right for you. And as long as you dive the thing regularly you should have no problem keeping your skills up.-Andy

 

[caveseeker7]

Pescador, Chris and Andy are correct, the PRISM is considerably more transparent in its operation and simpler to use than most electronically controlled CCRs.

If you read through the manuals of the APD units or the Ouroboros (both available for download) you realize that at least half if not more of the manual goes towards electronics. The PRISMs we use have a power switch, a HUD with 3 LEDs and an analog secondary with settings for the three O2 cells, setpoint verification and battery output. That's it, and it's as simple as electronic controls get.

The MK15.5 has similar electronics standard, but is larger and more expensive. It's less available
(since it's out of civilian production in the US) and a bit more maintainance intensive.

Haven't read one yet, but I doubt the manually controlled Jetsam models manuals take up much more space.

 

[padiscubapro]

Anyhow, my thoughts are that you will die sometime. If you scuba dive, you increase those odds of dying. If you use a RB, you increase your odds of dying.

At face value I don't agree with this statement..

If you are inexperienced on an RB and careless its true, but for the experienced CCR diver who doesn;t cut corners, RBs are probably safer..

I do many dives that I wouldn;t EVER consider doing on OC simply because the risk is too high, but On a CCR, the risk is accepable..

The biggest problem that a CCR eliminates is TIME.. on OC your time is limited by your gas supply.. Although a CCR does have a time limit for all practicality its not the limiting factor.. There are many divers that have run out of gas in overhead enviroments that probably would have lived if they were on a CCR..

I know personally I was deep inside a wreck, and my line got severed and there was near zero viz.. On OC I would have been ****ed.. I just put myself on the ceiling and waited for things to clear.. My bottom time was considerable longer than I planned for (If I was on OC I would have been out of gas).. I then was able to find my way out.. If I was on OC I would have hadto blindly search for an exit, and when the OH S**t factor hits you that you many die because you gas is gettig low things get even worse.. On my CCR I knew I would be able to push thigs out for several hours if necesssary.. This made it virtually stressful..

An EXPERIENCED CCR diver has many more way to get himslef out of tbl than an OC diver..

If a CCR diver has a total electronics failure and the loop is intact, they can choose to run it as a manual SCR and even a small 40cuft gas supply can be equivalent to a few hundred cu ft of gas.. If there is total failure bailing to OC is also a choice.. The oc gas carried is for emergency use so it should always be available..

I'm not saying a RB cant kill, but with the proper training and practice, Its a better option than OC for alot of dives..

 

[bruehlt]

At face value I don't agree with this statement..

If you are inexperienced on an RB and careless its true, but for the experienced CCR diver who doesn;t cut corners, RBs are probably safer..

I do many dives that I wouldn;t EVER consider doing on OC simply because the risk is too high, but On a CCR, the risk is accepable..

The biggest problem that a CCR eliminates is TIME.. on OC your time is limited by your gas supply.. Although a CCR does have a time limit for all practicality its not the limiting factor.. There are many divers that have run out of gas in overhead enviroments that probably would have lived if they were on a CCR..

I know personally I was deep inside a wreck, and my line got severed and there was near zero viz.. On OC I would have been ****ed.. I just put myself on the ceiling and waited for things to clear.. My bottom time was considerable longer than I planned for (If I was on OC I would have been out of gas).. I then was able to find my way out.. If I was on OC I would have hadto blindly search for an exit, and when the OH S**t factor hits you that you many die because you gas is gettig low things get even worse.. On my CCR I knew I would be able to push thigs out for several hours if necesssary.. This made it virtually stressful..

An EXPERIENCED CCR diver has many more way to get himslef out of tbl than an OC diver..

If a CCR diver has a total electronics failure and the loop is intact, they can choose to run it as a manual SCR and even a small 40cuft gas supply can be equivalent to a few hundred cu ft of gas.. If there is total failure bailing to OC is also a choice.. The oc gas carried is for emergency use so it should always be available..

I'm not saying a RB cant kill, but with the proper training and practice, Its a better option than OC for alot of dives..

Agreed - but don't forget - we are all human, and humans are not exempt from the laws of infallibility!

Its not a matter of if, moreso a matter of when!

 

[bradshsi]

For me the reason why rebreathers are not mainstream is summed up nicely by the accomplished rebreather diver Richard Pye:

http://www.iantd.com/rebreather/lgrb.html

Having spent the past two years developing my own procedures and protocols for decompression diving using closed-circuit rebreathers, I have learned some important lessons (Comper & Remley, 1996; Pyle, 1996d). After my first 10 hours on a rebreather, I was a real expert. Another 40 hours of dive time later, I considered myself a novice. When I had completed about 100 hours of rebreather diving, I realized I was only just a beginner.

Now that I have spend more than 200 hours diving with a closed-circuit system, it is clear that I am still a rebreather weenie

The kind of experience and attention to detail necessary to safely dive on rebreathers will exclude this type of equipment from being applied in the mass market. There is not a high enough % of the mass market scuba users who have the ability or time to meet these requirements.

From an engineering perspective rebreathers inherently tend to have more parts and therefore more things that can go wrong. Electronics in particular are a concern. It is a simple fact of life that a system with components in series only has a reliability equal to the product of all the individual components.

SystemReliability = Comp1reliability * Comp2reliability*...CompNreliability

In my job I sometimes design mission critical pumping systems pumping for powerstations. These will have 3 of every critical electronic sensor and a voting system (best 2 out of 3) to increase the reliability of the whole system to an acceptable level.

The above is not to say that rebreather are unreliable or dangerous per se. Simply that currently their successful use is beyond most people.

 

[wedivebc]

Just got off the phone with a buddy of mine. He's training his girlfriend on the sport kiss and he asks her (before breakfast) "you are at 100ft and your po2 is 1.2, what's the content of your loop?"
He's concerned she doesn't get the math for rebreather diving, I'm concerned he's turning into a RB nerd, but in any case these are things OC divers normally don't think about, let alone talk over with their GF first thing in the morning.

 

[JungleJoe]

Did you ever think the cost of such units also factors in Liability issues and insurance. You manufacture a rebreather and someone dies using it, you will get sued.....

So costs will be high till they become more mainstream me thinks.

Look at all the crap pilots and their aircraft have to go through. A simple radio for a plane is 5k, you can buy the same radio cept dif freq's in a marine radio for 90.00....

Liability and lawsuits are a big issue I have not seen brought up in this convo. I'd like to try out a RB sytem, but since I have been diving these past 25 years, I'm still ok with a bubble machine, I am one of those that happen to not use alot of air and my dive puter keeps me in touch with reality.

 

[caveseeker7]

... he asks her (before breakfast) "you are at 100ft and your po2 is 1.2, what's the content of your loop?"
He's concerned she doesn't get the math for rebreather diving, I'm concerned he's turning into a RB nerd ...

Y'all should be concerned about him soon being single again. Over breakfast ...
Why do I get the feeling an Oregonian would do that sort of thing?

Bradshi, Rich Pyle dives the single most complex rebreather ever sold to civilians, and he explores the twilight zone.

Most rebreathers are considerably simpler and transparent to maintain and dive.
You don't even need to have any electronics other than the standard three O2 cells
and an analog gauge.
No batteries, no computers needed if that's your choice.

But you are correct as is Pyle, any rebreather involves more maintainance and different skills.
And plenty of attention, it was Pyle who coined "Complacency Kills".

 

[bruehlt]

"you are at 100ft and your po2 is 1.2, what's the content of your loop?"

WHAT DO YOU DO HOTSHOT?! HUH? WHAT DO YOU DO! (ala the movie Speed)

 

[wedivebc]

WHAT DO YOU DO HOTSHOT?! HUH? WHAT DO YOU DO! (ala the movie Speed)

Actually I am pretty sure that's the way the conversation went with my buddy