100% 02 during your SI?

[ajduplessis]

O2 during an extended saftey stop will help as pointed out in some responses here. I would like to add to this in that you will require and DC capable of handling gas switches. It's pretty useless taking advantage of the breathing gas but your DC can't track it.

[waterpirate]

I think that the 02 on extended safety stop, maybe 10 minutes at ten fsw need not be tracked. It would be another layer of safety not part of the ongoing dive plan. It would take forever to run up the clock in this application, and switching a pressure group was not the objective.

It is done where I dive via boat supplied nitrox at 40fsw and up. Even on recreational charters it is used to clean up people who are not otherwise trained for other gas usages or more complex dive plans.

When you need to take credit for the higher 02 in your plan than tables or DC is needed.
Eric

[DaleC]

That's correct eric. If one wants to gain the benefit of accelerated deco one will need a tracking/adjustment system. If one wants to gain the benefit of safety margins from DCS one does not. In fact, if one does switch to a different gas model, they lose the primary advantage of reduced DCS risk.

[cmulvaney]

This March 11th could be very happy, by comparison. :-)

I hope all goes well. You will be in my thoughts.
Chris

[cmulvaney]

I dive Nitrox on just about all my dives. (Even in the pool) Since it is already paid for, it is not uncommon for me to use some of my remaining gas during my SI. Better to suck on 40% (or whatever mix depending on MOD) than 20.9%. I always seem to feel better than just plain old air during days 2 and beyond with multiple dives.

[Deep South Divers]

Thanks Chris.

[Max Speed]

Nicely put! In short, free radicals can be thought of as "body rust." Higher O2 percentages mean more body rust, and the idea behind the vitamin suppliments is to minimize the effects of it.

This isn't a problem. PADI offers a Scuba Review class if you're feeling rusty.

[danvolker]

Yes, I was always led to believe that ox-tox was the biggest killer of technical divers. I think the average tech diver would count as 'advanced', at least in the respect that they've been trained and tested on their buoyancy.. and intimately understand the relationship between ppO2, depth and toxicity.

Yes, an 'advanced' diver could do it... but it's a hell of a risk to take, without some external assessment to confirm that your suppositions about being 'advanced' are correct. Holding a decent stop 99 out of 100 times, just doesn't cut the mustard when breathing 100%.

Let's take an "advanced" diver...and by this I mean a good recreational diver, NOT a never-ever that just "passed" an AOW course that was impossible to flunk.

The advanced diver that I am talking to, must know that you do NOT want to breathe 100% o2 deeper than 20 feet given any choices.
But in the objections to this, the consistent objection that comes up, is what happens if this unwitting advanced diver runs OOA at maybe 100 feet, and has no buddy to get air from...he freaks, and grabs his regulator on his 100% pony bottle. So did my advice just kill him?

First answer, is that if he is so freaked that he would decide he needs the O2 instantly, rather than trying a free ascent....then I would say a breath of 100% O2 at 90 feet, another at 70 feet, another at 40 feet, and then steady breathing at 20 feet is going to keep this guy from drowning, and it would be much less likely for him to tox with this short exposure, than the chances of him drowning for lack of air...OOA has very definite and immediate ramifications.
Second, is that in the vast majority of tech diver deaths I have read about, or have knowledge of from doing the recovery, divers WILL breathe 100% for many minutes at 100 feet without toxing.... In the jane Orenstein Tech diver student death, Jane switched to the wrong gas at 120 feet--she was supposed to be going to a travel gas from trimix, and instead, switched to 100 percent....The instructor was her buddy, and failed in both jobs, by not watching the gas switch...Jane breathed this all the way up through her deco stops at to 30 feet, before toxing and sinking out of sight, with Instructor Derek Mcknulty of IANTD fame ( old rec.scuba thread of "Murder on the IANTD Express") , just watching her go..and making no attempt to save her.


In other words, an OOA diver in a huge rush to get to the surface from 100 feet, would most likely be better off breathing O2 on the fast inflated ascent, than potentially blacking out from going too long without air ( if they do not believe they can pull off a free ascent).

What I am saying is NOT that divers should do 100% o2 from 100 feet. I am saying they should not drown at 100 feet.

[PfcAJ]

I recall an incident not too long ago where a diver switched to o2 at ~50ft. He's dead.

[Thalassamania]

One "hears" lots of things, got any more details?