the great RB vs OC debate

[wedivebc]

Mike said some things on another thread that got my back up so I am posting it here. I thought we could post it on the rebreather forum but it might make my side a little stronger. I decided against the DIR forum since they only acknowledge 1 real rebreather and before you suggest it I already thought the accidents and incidents forum would have a certain irony So here it is:

yes. One issue is being certain of what you're breathing. The toy rebreathers use a fixed orifice and don't measure po2 without modification.

Yes and your regs probably didn't come with a SPG but I bet you don't dive without it.

With others you're relying on a computer to control and tell you what you're breathing.

What about manual CCR like the KISS? The electronics tell you what you are breathing, your brain tells you what to do about it.

With OC, I know what I'm breathing. Diver error or not, there's been lots of rebreather deaths caused by the diver not breathing what he thought he was.

I think that issue is not exclusive to RB divers. There are lots of OC divers who died because they didn't know what they were breathing either.

The other issue is decompression strategy. The rebreather camp (closed circuit constant po2) is happy minimizing deco where the OC camp would rather keep po2 down and save the slam for decompression.

This issue is one I would be happy to listen to your side of the argument provided you don't post GI3's rant about it 'cause I've read it. If you have an authoratative resource I will be willing to understand your position. Mine is that most TOX hits happen at the shallow, high fO2 stops and are likely due to the sudden spiking of PO2

The constant fo2 rebreathers (other than those like the Halcyon where you plug in any gas you want) aren't used for anything serious as far as I know. I think they're just fancy recreational toys. Being stuck with a couple selections of nitrox keeps you in the kiddie pool although you can stay there a long time. LOL

The example that started this whole thing was that the guys with all the kit were paddling in the same kiddie pool as us. I won't argue that SCRs are less capable than a CCR but the toy rebreathers we were diving was going the same place our heros were.

 

[Rick Murchison]

THE question to me (aside from the obvious value in low He use and silent running = more critters to see) is the constant PPO2 vs the OC method of dropping and then spiking PPO2 during ascent and switch to deco gas... physiological implications pro or con, accomodation of air breaks, etc.
I can argue both sides with myself academically and still leave myself with considerable uncertainty as to those risks/benefits - so I'm asking y'all to enlighten me from your knowledge base and experience.
Thanks in advance.
Rick

 

[boomx5]

If you have an authoratative resource I will be willing to understand your position. Mine is that most TOX hits happen at the shallow, high fO2 stops and are likely due to the sudden spiking of PO2

Dave I don't have a dog the fight here, and I'll admit that my RB knowledge is limited at best. However, I would like to know what you consider an "authorative resource" to be? Is it someone who knows all the theory and crunches numbers, or is it someone who actually does the dives?

 

[wedivebc]

Dave I don't have a dog the fight here, and I'll admit that my RB knowledge is limited at best. However, I would like to know what you consider an "authorative resource" to be? Is it someone who knows all the theory and crunches numbers, or is it someone who actually does the dives?

Someone who does the dives means little since deco physiology/strategy involves the system being emperically tested in different environments and using various physical variables. One person doing umpteen thousand dives in the same caves at a constant 74'F with a huge support team means little to me in the cold, choppy, murky waters of the north Pacific.
So yes I would like to hear from someone other than 'you know who' or one of his representatives who will just quote Him anyway.

 

[boomx5]

Someone who does the dives means little since deco physiology/strategy involves the system being emperically tested in different environments and using various physical variables. One person doing umpteen thousand dives in the same caves at a constant 74'F with a huge support team means little to me in the cold, choppy, murky waters of the north Pacific.
So yes I would like to hear from someone other than 'you know who' or one of his representatives who will just quote Him anyway.

You don't think that "the system" is being tested to this day by different divers in all different environments all over the world? Your willingness to dismiss the work done down there, it seems you've already come to the conclusion in your own mind, and are not open to anything other than an argument...is that why you started this thread?

 

[wedivebc]

You don't think that "the system" is being tested to this day by different divers in all different environments all over the world? Your willingness to dismiss the work done down there, it seems you've already come to the conclusion in your own mind, and are not open to anything other than an argument...is that why you started this thread?

No but I am looking for a fresh perspective. I have read what GI3 has to say on the subject. I will debate all you like just get some fresh material.
I have a friend who is a fundementalist Christian. I am not a heathen by any means but any discussion we have of a philosophical nature end with "the bible said it, I believe it and that settles it" . So unless I accept his doctrine there is nothing more to discuss. It's the same with you guys. I have an open mind, just bring some fresh facts to the table and I'm all ears.

 

[boomx5]

No but I am looking for a fresh perspective. I have read what GI3 has to say on the subject. I will debate all you like just get some fresh material.
I have a friend who is a fundementalist Christian. I am not a heathen by any means but any discussion we have of a philosophical nature end with "the bible said it, I believe it and that settles it" . So unless I accept his doctrine there is nothing more to discuss. It's the same with you guys. I have an open mind, just bring some fresh facts to the table and I'm all ears.

Fair enough. Let's hear some fresh facts...who wants to start?

 

[Rick Murchison]

No but I am looking for a fresh perspective. ... I have an open mind, just bring some fresh facts to the table and I'm all ears.

Ahem... Excuse my plebian lack of sophistication, but could you explain the difference in a "fresh" fact and a fact that ain't fresh?
Does the age of a fact have something to do with its veracity?
I must have missed something.
Rick

 

[Curt Bowen]

No but I am looking for a fresh perspective.

Give us a suggestion on what fresh perspective your looking for?

 

[wedivebc]

Give us a suggestion on what fresh perspective your looking for?

I want to know why low PO2 dives with high PO2 deco spikes are considered better by some when the risk of TOX from O2 spikes and the deco tables I use tell me moderate PO2 at bottom mix and slightly higher PO2 for deco get me out of the water way faster. If I consider my way safer and faster what makes a 100ft for 50 min dive using 21/35 and O2 deco gas better than using NTX 35 with o2 deco when my software (V-planner) tells me I get out 12 minutes earlier?