Rebreather Discussion from Brockville Incident

[HIGHwing]

Do you use a check-list?

Every dive, every flight.

I check my tanks for O2, He, CO, and CO2.

What are you using to check your tanks for CO2, and why do you suspect a possibility of a presence of that gas fraction?

IF your arugment is your process for OC diving is infallable, and flawless, come up with one really good reason you should be diving a rebreather? With enough planning/equipment OC can be faster through deco, and another layer of felt gives you the warmth under a dry suit.

You've suitably convinced me you do not accept all the risks with diving a CCR, and I'm trying to figure out why you're doing it.

 

[mathauck0814]

What people like me want to know - OC divers who are considering CCR - is what is the additional risk that I will be assuming given the non-deco, single gas dives that I am doing now. Mistakenly breathing a hypoxic bottom mix or ox-toxing by switching to too rich a mix at depth just isn't something that I have to deal with now, so to say that these types of accidents are just as much a problem with OC doesn't really ring true for the vast majority of certified divers.

Unless you're deriving your income from underwater photography, I honestly can't see a good reason for any diver doing single gas/NDL dives to switch to a rebreather. The benefits you derive from the machine come in the form of gas volume efficiency (using less Helium, which can be difficult to find at times), gas mix efficiency (constant PO2 which can result in less decompression on "medium" depth diving) and increased options for SHTF scenarios on "deep" dives. None of which will help you much in the recreational realm.

Sure you'll get extended NDL due to the constant PO2 - so you'll be able to stay at 120 feet on your favorite wreck longer than on open circuit. For your trouble you get to deal with the hassle and (relative to OC) high cost of consumables of the rebreather in addition to the (relatively minor) additional risks being largely exaggerated in this thread.

Recreational rebreather use as PADI and others propose, in my opinion, is simply a way to sell expensive toys to gear heads.

 

[HIGHwing]

Recreational rebreather use as PADI and others propose, in my opinion, is simply a way to sell expensive toys to gear heads.

Exactly. You're going to drop $5,000 - $7,000 on a machine, spend over $1,000 in training, have to buy $1,500 in accessories (bailout, computers, etc.) probably travel with your OC gear anyway. Where is the payoff? It's just not there because the per minute dive cost doesn't come close to approaching the price delta presented in deep OC trimix diving versus the same dive on CC.

 

[doctormike]

Unless you're deriving your income from underwater photography, I honestly can't see a good reason for any diver doing single gas/NDL dives to switch to a rebreather. The benefits you derive from the machine come in the form of gas volume efficiency (using less Helium, which can be difficult to find at times), gas mix efficiency (constant PO2 which can result in less decompression on "medium" depth diving) and increased options for SHTF scenarios on "deep" dives. None of which will help you much in the recreational realm.

Sure you'll get extended NDL due to the constant PO2 - so you'll be able to stay at 120 feet on your favorite wreck longer than on open circuit. For your trouble you get to deal with the hassle and (relative to OC) high cost of consumables of the rebreather in addition to the (relatively minor) additional risks being largely exaggerated in this thread.

Recreational rebreather use as PADI and others propose, in my opinion, is simply a way to sell expensive toys to gear heads.

Thank you! That makes a lot more sense to me than the endless discussion of safety standards and O2 sensors..

Seriously, I understand that there is a lot to discuss here, and a lot of good statistics to be done, but the lack of reliable and uniform data collection (like we have for aviation) makes it hard to do that research.

I have sold a few photos and made a few covers, but I'm certainly no UW Photo pro, and it doesn't seem like this is a leap that I need to take. So do I take it that the various factions of the rebreather community are united in being skeptical about PADI selling CCRs to people with 25 dives? Or is there a role for less complex gear / SCRs in this space (like the KISS GEM)...?

 

[mathauck0814]

Exactly. You're going to drop $5,000 - $7,000 on a machine, spend over $1,000 in training, have to buy $1,500 in accessories (bailout, computers, etc.) probably travel with your OC gear anyway. Where is the payoff? It's just not there because the per minute dive cost doesn't come close to approaching the price delta presented in deep OC trimix diving versus the same dive on CC.

The challenge I see is that shops are using a timeshare model to attract new CCR divers. Artificially lowering the cost to induct folks. Training and consumables remain.

 

[gianaameri]

Every dive, every flight.



What are you using to check your tanks for CO2, and why do you suspect a possibility of a presence of that gas fraction?

IF your arugment is your process for OC diving is infallable, and flawless, come up with one really good reason you should be diving a rebreather? With enough planning/equipment OC can be faster through deco, and another layer of felt gives you the warmth under a dry suit.

You've suitably convinced me you do not accept all the risks with diving a CCR, and I'm trying to figure out why you're doing it.

I happen to have a spare CO2 Sensor (I removed it from the rebreather), so I use it to check the tanks for CO2.

A properly designed filling station, if functioning properly, would convert by filtration the CO (if any is produced) to CO2. So, in addition to the 0.03% - 0.05% normally in ambient air, you could find a not insignificant presence of CO2 in the tank (which means you have a big problem with your compressor).

Interestingly enough, if that were to happen, on OC you could die, but not on rebreather because the CO2 absorbent would remove the excess CO2 (if it is not too much of course).

I have explained why I dive rebreather in a prior post.

For certain cave dives, it is logistically preferable to use a rebreather. I would need 10 Sherpas to carry up and down the equipment for me in and out of the cave if I were to do the same dive on OC.

Other than for long cave dives over a series of consecutive days, I do not use a rebreather.

Before I fully understood the true risks inherent in rebreather diving, I used to use the rebreather every dive. Now, I avoid it like the pest whenever practicable.

It is a useful tool though under some circumstances where the benefits outweigh the risks of using a rebreather.

 

[HIGHwing]

The challenge I see is that shops are using a timeshare model to attract new CCR divers. Artificially lowering the cost to induct folks. Training and consumables remain.

Seriously?

 

[mathauck0814]

Seriously?

Sadly - nothing on their websites, unfortunately, but both Ocean Enterprises in San Diego and Scuba Schools of America up toward LA are doing "group ownership" Poseidon programs. ~$500/year gets you access to rental use of the unit (which comes pre packed with sorb and oxygen).

Seems an avenue to sell training and ultimately to ease people into wanting to own their own units.

Personally, I'd not prefer a machine prepared by someone else (only one person at the shop I'm thinking of would be CCR certified, so being prepared by someone else who knows nothing of rebreathers, presumably) that was recently dove by someone else (who had no obligation to report any sort of malfunction) etc. All around a terrible idea.

Ocean Enterprises Makes Rebreather Diving Possible for You! ? Ocean Enterprises Dive Blog - Around 2/3 down the page on the right it mentions, "Time Share Ownership Opportunities" but they don't go into more specifics on their site.

 

[tridacna]

Scuba Schools of America up toward LA are doing "group ownership" Poseidon programs. ~$500/year gets you access to rental use of the unit (which comes pre packed with sorb and oxygen).

Rusty and Rebreathers and newbie students? This can only get more interesting. :signofcross:

 

[HIGHwing]

Personally, I'd not prefer a machine prepared by someone else (only one person at the shop I'm thinking of would be CCR certified, so being prepared by someone else who knows nothing of rebreathers, presumably) that was recently dove by someone else (who had no obligation to report any sort of malfunction) etc. All around a terrible idea.

Perhaps, like with airplanes, they'll develop a squawk sheet so they renter will know what's been done/fixed/replaced/updated. If it's already assembled you don't get to see the cell dates, health, no pressure pot checking. No way.

I assume what's going on here is you're buying your own battery for the $500, you're paying for the training, and then paying a rental. That reduces the cost of entry, but who knows how many casual divers have saved themselves from an untimely demise by the financial barrier. You sorta have to be a pretty avid diver to be diving a rebreather just to stay current on the machine, etc. I don't think the machines are quite mature enough to dive it four times a year in ____ resort and diving center and be proficient. Yikes!