Something not sound right about this?

[Rick Murchison]

... In some studies (by Kenneth Donald??), it took 75 minutes at 3ata ppO2 before 10% of the subjects had CNS toxicity symptoms.

But one convulsed in FIVE minutes. On the FIRST exposure.
Let's not confuse things here. The statistical probability of an O₂ hit becomes UNACCEPTABLE - unsafe - for in-water deco on oxygen below 20 fsw. Those "mystery" disappearances years ago are why the limit was moved back to 1.6 in the first place. You can probably get away with Russian roulette, too... five out of six times... but the sixth is liable to be first.
Don't go there.
Rick

 

[Kevin Carlisle]

In a more direct approach yep. I would still lean more towards the person in question and his dive plans are probably more BS than anything else.

I believe what y'all were trying to say is God protects fools and drunks.

 

[dwhthediver]

I have to agree with Rick, breathing O2 below 20' is russian roulette, the 1.62 pp O2 is right at the line for being stupid, and that is what it works to at 20', breathing pure O2 at 30 is a statistic waiting to happen. I have to agree with everyone who says that those words are either bs, or this moron has been the luckiest sob in FL so far

 

[Charlie99]

I have to agree with Rick, breathing O2 below 20' is russian roulette, the 1.62 pp O2 is right at the line for being stupid, and that is what it works to at 20', breathing pure O2 at 30 is a statistic waiting to happen. I have to agree with everyone who says that those words are either bs, or this moron has been the luckiest sob in FL so far

While I'm not advocating O2 at 30' (a ppO2 of 1.9ata), nor would I do so myself, you seem to have a greatly exaggerated idea of the risks involved -- both higher risk than most of us are willing to accept, but definitely not guaranteed death sentences and probably not even a 1% fatality rate.

The Belgian Navy for a very long time had a ppO2 limit for their divers of 2.3ATA. Until recent decades, the USN allowed pure O2 rebreather divers spend lots of time at 2.0ata and to even make short excursions deeper (to 40'/2.2ata IIRC).

And then of course, modern day hyperbaric chambers usually provide pure O2 at 60'/2.8ata. Yes, there a few patients that experience seizures over the course of several hours at 2.8ata ppO2, but they are a small minority --- and that is at 2.8ata, not the 1.9ata of 30'. (And yes, I know that you do drown in chambers, while you do at 30' under.) There is a whole lot of history and data that says that while starting O2 deco at 30' is pushing the envelope (as is 200' on a single tank of air), the diver is much more likely to get away with it than he is to have problems. Both the 200' on single tank air and starting O2 deco at 30' are somewhat consistent with each other.

Kind of like running across a freeway. I won't do it, but most of the time the idiots that do manage to avoid getting hit.

 

[Rick Murchison]

The Belgian Navy for a very long time had a ppO2 limit for their divers of 2.3ATA. Until recent decades, the USN allowed pure O2 rebreather divers spend lots of time at 2.0ata and to even make short excursions deeper (to 40'/2.2ata IIRC).

And why did both abandon that practice, do you suppose?
Rick

 

[ucfdiver]

My bet is that it's a bunch of exaggeration, unless the poster is in his 20's. Many 20 year olds are immortal, or least so they believe.

Way to stereotype. The group I dive with (mostly in their 20's) are all very conservative when it comes to safety. As a matter of fact, the worst divers I've dove with are older divers who have grown complacent.

 

[Supershark]

Way to stereotype. The group I dive with (mostly in their 20's) are all very conservative when it comes to safety. As a matter of fact, the worst divers I've dove with are older divers who have grown complacent.

Agree 100%. I am 30, been working at a CDC training guys of all ages and experience. The worst one ever was a 55 year old DM who thought he knew everything. He now knows lots about the cost of the chamber and medical fees related to dive accidents!

 

[Charlie99]

And why did both abandon that practice, do you suppose?
Rick

The same reason that cars now have seatbelts --- to further reduce risk. I can't imagine how wild and crazy people were back in the 50's and 60's, driving around without seatbelts. Somehow, we didn't wipe out the entire human race.

I always use my seatbelt, but if somebody tells me that they choose not to, I don't jump to the conclusion that they are going to die the next time they get into their car.

 

[Charlie99]

Way to stereotype. The group I dive with (mostly in their 20's) are all very conservative when it comes to safety.

I plead guilty as charged.

The thing about stereotypes is that there is generally a kernel of truth behind them.

Although the group of 20 year olds that you know are all very conservative divers, many young males are not. Just ask any automobile insurance company. (ooops, I guess I just added gender stereotyping too!)