Setpoint during fast decent, what do you use?

[Seameadow]

Have a look at the presentation by Simon M, from the point in the link, but maybe the whole video. Quicker than reading and put in laymans terms.

 

[Wibble]

The pile-on seen here is really misplaced.

One person asks a question, which was based on older thinking -- not the modern gas densities, etc. -- and it results with a pile-on where the man's attacked, not the ball.

This short-sighted posting may get the posters some form of satisfaction, but it doesn't do much for a reasoned debate over contemporary thinking: theory as well as practice.

The OP's comments indicate a more OC approach to CCR planning which may have been fairly typical amongst rebreather divers a decade or more ago. Those people lived through it. The OP's diving with higher PPO2s would mean he lives through it so it's not "dangerous" per se. Obviously the OP would need to adjust his dive profiles and react to any issues promptly, much more so than someone using leaner oxygen and richer helium.

 

[grantctobin]

Those people lived through it.

Survivorship bias - Wikipedia

en.m.wikipedia.org

 

[berndo]

which may have been fairly typical amongst rebreather divers a decade or more ago.

No, it wasn't. The gas desinty was a thing and well know even among OC divers 20 years ago and so was END and the issue with high O2 at depth.

Those people lived through it. The OP's diving with higher PPO2s would mean he lives through it so it's not "dangerous" per se.

You really should read the wiki article @grantctobin posted. The OP is like a person who's been driving drunk for 10 years and saying it's no problem and not dangerous because he's still alive.

 

[Agro]

You did

Where did I say so?

 

[Agro]

The OP is like a person who's been driving drunk for 10 years and saying it's no problem and not dangerous because he's still alive.

Wrong comparison. And you know it is wrong.

 

[kensuf]

The pile-on seen here is really misplaced.

One person asks a question, which was based on older thinking -- not the modern gas densities, etc. -- and it results with a pile-on where the man's attacked, not the ball.

This short-sighted posting may get the posters some form of satisfaction, but it doesn't do much for a reasoned debate over contemporary thinking: theory as well as practice.

The OP's comments indicate a more OC approach to CCR planning which may have been fairly typical amongst rebreather divers a decade or more ago. Those people lived through it. The OP's diving with higher PPO2s would mean he lives through it so it's not "dangerous" per se. Obviously the OP would need to adjust his dive profiles and react to any issues promptly, much more so than someone using leaner oxygen and richer helium.

I've seen a lot of people making comments like "if your instructor didn't go over gas density in your <x> class" on a number of forums and have been gobsmacked. The new religion is focusing on one thing but missing out on a dozen other variables that contribute to problems, and in many cases may be more important than the density of the gas someone is breathing.

Workload, bore size, absorbent type, bed depth, counterlung placement, CL volume, cardiovascular fitness, etc are as important, if not more so. Anyone that's ever dove an SF2 can tell you how when you get out of trim the breathing can suck (or blow) badly.

I'm absolutely amazed when I see people buying budget regulators that have crappy exhaust work of breathing or dive CCR's with crappy WoB due to design decisions, that then condemn instructors that don't teach gas density. Gas density, on the other hand, can be taught as simply as saying "keep your END shallower than 100ft/30m" and you've covered it until someone begins going deeper than 220m/720'.

 

[berndo]

Wrong comparison. And you know it is wrong.

You're impaired while operating a machine that needs attention to operate safely. You're ignoring all safety rules that we learned from looking at fatal accidents. It's a pretty good comparison.

More accurate of a comparison would be riding a motorbike drunk without a helmet in shorts and a t-shirt and saying you never had a problem and never needed a helmet and have never even heard about a helmet before.

(I don't even wanna know how you plan your bailout or for how long you use your sorb and cells.)

 

[Agro]

You're ignoring all safety rules

A lie does not become more true by repeating it.
ALL safety rules? ALL? There are hundreds.
Yes I have no problems at all having a pO2>1.3 for a short time, no matter if OC or CC. Some people believe this will kill me. Does 100% O2 kill you at 6m?
Yes I have no problems with END of 40 or 50m. I often dive OC on air to this depth, so what? Thousends of divers do so as well.

 

[Agro]

I've seen a lot of people making comments like "if your instructor didn't go over gas density in your <x> class" on a number of forums and have been gobsmacked. The new religion is focusing on one thing but missing out on a dozen other variables that contribute to problems, and in many cases may be more important than the density of the gas someone is breathing.

Workload, bore size, absorbent type, bed depth, counterlung placement, CL volume, cardiovascular fitness, etc are as important, if not more so. Anyone that's ever dove an SF2 can tell you how when you get out of trim the breathing can suck (or blow) badly.

I'm absolutely amazed when I see people buying budget regulators that have crappy exhaust work of breathing or dive CCR's with crappy WoB due to design decisions, that then condemn instructors that don't teach gas density. Gas density, on the other hand, can be taught as simply as saying "keep your END shallower than 100ft/30m" and you've covered it until someone begins going deeper than 220m/720'.

That's exactly the point I do not understand. Why is gas densitiy a problem on CC and it is not on OC? I can perfectly breath air at 80m on OC. Why is CC 12/35 at 60m a density problem? I fully understand that higher He reduces density but which amount of density is OK?