100% 02 during your SI?

[Deep South Divers]

Wow.

I see Thal's point and totally agree with him... Stopping at a given depth and switching out regulators is far from a "technical" concept, and shouldn't require an entire course to make that happen. I mean, really? A whole course? Another merit badge? Really?

Still, I mentioned training at the end of my original answer so as to avoid having the target painted on me.

Thal, I'm with you on this one. But don't tell anyone - I'm not interested in the heat.

Ulfhedinn, sling an AL40, marked appropriately, on your left side with a 50% blend. Use it above 70' only. Practice your stops. Do this with an experienced "technical" buddy or better yet, a "technical" dive instructor - you'll need to anyway, to have them show you how to set up and use that regulator concerning the hose routing. Get good at it. You'll notice that your dives get longer while your pressure groups get lesser.

This practice should INCREASE your margin of safety, not DECREASE it... But only if you use the gas appropriately - above 70' for a 50% O2 mix. Yes, it really is that easy.

Now, don't take our word for it - get trained properly. (<--CMA)

For what it's worth, you could easily practice this switch by slinging a bottle of the same gas on your back. For example, if you were on a single tank with air on a 35' reef dive, there's nothing that says that you can't sling an AL40 with air in it, too, just to have an additional 40 cuft of air and a completely redundant gas supply, "just in case." This would allow you to practice your "gas switches" without the "complexity" of different gasses.

Also, for what it's worth, that would qualify as a completely redundant gas supply, a requirement in some agency's solo diving courses. Not that I recommend diving solo, of course... I'm just sayin' that some agencies consider using this sling-bottle setup so much safer than NOT using one that they'll certify you for solo diving with it and won't without it. Just sayin. Training. (<--CMA)

Once you got the approval from your instructor (<--CMA), you could try different gas mixes in different bottles for different reasons. A common and useful one MIGHT BE (<--CMA) a 50% mix slung, and marked appropriately with a big "70" on the side to remind you not to use it below 70'. Have your "technical" instructor show you how to do this. (<--CMA) A combination of 32% (or 36% if you like) as back gas with a 50% sling bottle would keep your pressure groups very shallow.

 

[Thalassamania]

Look, the whole worry here is that the poor stupid slob will, in the heat of an emergency, go to his O2 bottle rather than his auxiliary. Now, if he is using a necklaced auxiliary, that is not an issue. If he is using an integrated inflator/auxiliary that is not an issue. It is only an issue if he is using a standard octopus with a second stage that is of the same design as the regulator that is on slung bottle and that is secured in a similar manner and location. So ... we're already passing small in the way of real potential problems. Now, let's look at the rest of it:

• the slung bottle should have a charged line but the valve should be off. So even if he made a mistake he'd know it rather quickly.
• oxygen is not a one toke and you're dead kind of situation within recreational depths, in fact, I would be very surprised if a diver had any problem going into pure O2 at recreational depth and immediately starting up. I've breathed it, in a chamber, for as long as 20 minutes as deep as 60 fsw.

So, when you consider how difficult it would be to use the wrong gas and how unlikely it would be to suffer any damage, even if one were to use the wrong gas, I can only conclude folks who have heartburn over carrying a single sling bottle without a course in how to do so, as has been suggested here, either have not thought the whole thing through or have some other agenda running.

Frankly, I'd start making sure I could hold a stop, then I'd add a slung bottle of air and work with it till it was second nature, and only then would I consider going to the real thing ... but then I'm unusually cautious and risk adverse.

 

[Captain12Pk]

A bottle switch is not necessarily a technical skill.
A gas switch to EAN 50 or 100% O2 IS a technical skill.
EAN 50 and O2 ARE decompression gasses.


You are free to give whatever internet advice you see fit. And I am free to disagree with your choice to do so.

 

[Thalassamania]

Air is the most used decompression gas in the world.

I would argue that all mandatory decompression diving is, "technical diving."

I do not think that all divers require "technical diving" training to learn to be "technical divers."

 

[DevonDiver]

I don't think that all non-divers need training to dive. Some non-divers probably don't need training to technical dive.

Is that a reason to argue against limitations and boundaries in line with progressive training?

A capable human being, possessed of common-sense and the ability to follow simple directions - coupled with a few hours on the internet - could probably get to 100m and back, using helium and multiple stages.

Whether they could repeat it 100 times is questionable. Whether they could complete it if something went wrong is also questionable.

 

[Thalassamania]

I don't think that all non-divers need training to dive. Some non-divers probably don't need training to technical dive.

Is that a reason to argue against limitations and boundaries in line with progressive training?

A capable human being, possessed of common-sense and the ability to follow simple directions - coupled with a few hours on the internet - could probably get to 100m and back, using helium and multiple stages.

Whether they could repeat it 100 times is questionable. Whether they could complete it if something went wrong is also questionable.

That's an idiotic strawman, no capable person possessed of common-sense would, by definition (common-sense, remember) attempt one or a hundred descents to 100m with nothing but a few hours on the internet. Someone might, however, read a bit, ask a bit, practice shallow, work their way up to it, and then dive to 100m, and likely do it as well as any of the "techies." Lord knows, that's basically how I did it, though there was no internet, no techies and few books on the subject.

 

[danvolker]

I don't think that all non-divers need training to dive. Some non-divers probably don't need training to technical dive.

Is that a reason to argue against limitations and boundaries in line with progressive training?

A capable human being, possessed of common-sense and the ability to follow simple directions - coupled with a few hours on the internet - could probably get to 100m and back, using helium and multiple stages.

Whether they could repeat it 100 times is questionable. Whether they could complete it if something went wrong is also questionable.

OK, clearly you are stirring the pot for fun here.....Internet antics aside though....
Back in the 60's and 70's, a large percentage of the actual divers, had recieved zero classes....they just bought gear, and had some diver they knew tell them the handful of important details they had to remember--like, "when you run OOA, start exhaling and haul ass for the surface" ...
In any event, there will always be a "population" of athlete/adventure types that do not really need formal instruction. In today's world, they will get it, just the same....insurance and mandated certs to go on boats pretty much enforces this. However, for this group, forcing them to take a course on how to breath off of a pony tank at 20 feet is just ridiculous. The only issue is whether or not the person in question is actually one of these people that is an athlete/adventurer type that picks stuff like this up, as if they had always knoiwn it...


While I believe this, I also believe that even these adventure types, would benefit enormously from classes like Peak control bouyancy or GUE Fundamantals...or a REscue class...things that are not intuitive, and are also very valuable.

 

[DevonDiver]

That's an idiotic strawman,..

Fair point.

no capable person possessed of common-sense would,...

...undertake a venture that is potentially lethal if done incorrectly or a mistake is made, when effective training is easily available.

I could say the same about using O2 in the water.

Yes, the 'skill-set' for gas switching is basic. But carrying a hypoxic mix well below it's MOD requires a 'mind-set' also.

Maintaining a precise stop is a fairly basic skill-set also. Doing so under any circumstance, without distraction or loss of focus, is a 'mind-set'.

I'm sorry, but I am in the water with 'Joe the Recreational Diver' every day. I just wouldn't want to see them chugging 100% on a shallow stop.

Back in the 60's and 70's, a large percentage of the actual divers, had recieved zero classes....they just bought gear, and had some diver they knew tell them the handful of important details they had to remember...

Yes, that's true and very valid. Those divers didn't have classes. More importantly, they didn't have PADI classes. Are we under the impression that training quality improved with the evolution of mass-market scuba tuition?

I wrote about this on a different thread earlier today: http://www.scubaboard.com/forums/ad...l-diving-serve-any-purpose-6.html#post6126199

Modern divers aren't comparable to the divers of the 60's and 70's. Different generation, different training, different mind-set. Yes, there are still 'adventurers' out there - but that's a tiny minority now. If we are only talking about a tiny minority - who have access to solid mentorship and display a great mind-set... then fine. If we're talking about 'any' scuba diver.... then your average McDiver product of the PADI system probably shouldn't play around with O2 underwater.

 

[Rich Keller]

Does anyone breath 5mins or so of 100% 02 between dives? Seems like it would assist in lowering your PG. Is my thinking off>?

Surface O2 is not going to help that much for reducing the nitrogen but it is great for when you have a hang over.

 

[danvolker]

Surface O2 is not going to help that much for reducing the nitrogen but it is great for when you have a hang over.

Rich, I agree most of us dont need it, but there are divers who come up from most of their dives, who are bubbling pretty good ( if a doppler was done they would see this)...whether because of a PFO, or really bad fitness..in any event, the surface O2 could resolve those bubbles well, which could otherwise become sub-clinical DCS....making them tired and maybe slightly stiff or inflamed feeling....

An even more appropriate example of a "category" of diver that could benefot from surface O2, or the 20 foot stop O2, would be underwater photoggraphers with great big heavy camera and strobe systems, that require constant contraction of the arm and shoulder muscles throughout each dive.....when you run dopplers on this behavior, it becomes apparent that the constant muscle contraction cause constrictions in the blood flow of the wrists, elbows and other parts of the arms, and this causes an unhealthy increase in bubbling. We saw this from some of the WKPP doppler studies done back in the late nineties....
What I did for Sandra and her big camera set up, is get her to put some straps on the arms of the camera so she could clip it to her chest during a long safety stop, and relax the muscles in her arms, and get the total bloodflow going again....this actually made an enormous difference to how should would feel the next day....this same advice has done exactly the same thing to each other photographer we had try this....O2 would be better still, at the 20 foot stop...and surface O2 would also help resolve the bubbling in those that can't or wont, clip off the camera, and are not comfortable with the O2 underwater. There are MANY underwater photographers that get arthritis in wrists and elbows after years of underwater photography....I believe some day the agencies will show this is linked to "micro hits" or bubbling from constricted muscles....