No Technical Training for Me.

[MikeFerrara]

Perhaps the real reason some use 80% is that that is just about the highest O2% you can get in a 3000 psi bottle without a boster.

2200 psi O2 (standard max fill for most O2 storage tanks from gas suppliers) topped with 800 psi of air will gived you 80% O2.

Don't let anyone else BS you, if they are using 80% and don't have a booster it is the most they can get.

I get 'T' bottles of aviation grade O2 at about 2600 psi. I keep several around so I can bank them. I get my 80 cu ft decompression bottles up over 2000 psi. That will get you through a VERY long dive. Now if I topped off my O2 bottle with air (mostly nitrogen) I'd have EAN80 LOL but what is all that nitrogen doing for me?

Adding air because you don't have a booster doesn't accomplish anything. I've never done a dive where 50 cu ft of O2 wasn't enough but if I did, I would bring a second bottle of O2 before puming a bunch of nitrogen in.

 

[ianr33]

80% is just a ridiculous choice. I usually don't outright say that a gas selection is foolish, but this one is.

If 80% is a ridiculous choice then 50% (if using only one deco gas) would be totally ludicrous.

I agree (100%!!) that pure 02 is the best choice,but totally slamming 80% is just regurtitating Cool Aid.

 

[MXGratefulDiver]

If 80% is a ridiculous choice then 50% (if using only one deco gas) would be totally ludicrous.

I agree (100%!!) that pure 02 is the best choice,but totally slamming 80% is just regurtitating Cool Aid.

Out of curiosity ... do any other tech agencies forbid the use of 80%, or is that strictly a GUE thing?

My NAUI Tech instructor said he prefers 100% but that there are times when 80% is a reasonable choice ... he's an old-school diver with decades of Coast Guard and commercial experience.

... Bob (Grateful Diver)

 

[Spratman]

I did my Intro to Tech Diving last year with NAUI. My instructor had us do all our skills repeatedly with buddy teams. We were doing it all in a quarry from April until July. All our dives were above 60 feet. Okay, maybe we were slow learners, however, he didn't pass us until we did everything correctly and on time.

I would recommend Intro to Tech to any diver that wants to dive better. If you are going the GUE route, then Fundies is for you. I didn't like the jam it into a weekend curriculum.

I really learned a lot from the class. I wanted to take the Adv Nitrox and basic deco class this year, and my instructor told me to dive this year, and think about it next year. I ask his advice. I may not like it but I listen to him. However, he is the only instructor that I've had that I trust that much.

 

[Gilldiver]

I get 'T' bottles of aviation grade O2 at about 2600 psi. I keep several around so I can bank them. I get my 80 cu ft decompression bottles up over 2000 psi. That will get you through a VERY long dive. Now if I topped off my O2 bottle with air (mostly nitrogen) I'd have EAN80 LOL but what is all that nitrogen doing for me?

Adding air because you don't have a booster doesn't accomplish anything. I've never done a dive where 50 cu ft of O2 wasn't enough but if I did, I would bring a second bottle of O2 before puming a bunch of nitrogen in.

I was not going into why to use 80%, I was pointing out how that magic number first came about.

For myself, I can take a 40cf bottle to bank pressure of 2200 psi and do my DECO after a 200' dive at 20 and 10 just fine.

 

[Rick Murchison]

Don't let that deter you. Just find an instructor who knows what he's doing. That one doesn't...a good hint was the 80% deco gas.

How's the Kool Aid these days Soggy?
Rick

 

[Soggy]

If 80% is a ridiculous choice then 50% (if using only one deco gas) would be totally ludicrous.

No, in fact that's not true. 50% is about getting on a gas much much earlier (not just 10 ft!?!) and is best when used with helium mixtures, as you will offgas the helium earlier in the ascent. It's a completely different issue than 80%, which is pointless.

I agree (100%!!) that pure 02 is the best choice,but totally slamming 80% is just regurtitating Cool Aid.

No cool-aid here, man. My reasons are my own. Notice how no one has yet to come up with a coherent argument for its use? There's a reason for that.

 

[Soggy]

Out of curiosity ... do any other tech agencies forbid the use of 80%, or is that strictly a GUE thing?

Well, NAUI Tech standards are 100% O2. Talk to Mr. Weinke about

My NAUI Tech instructor said he prefers 100% but that there are times when 80% is a reasonable choice ... he's an old-school diver with decades of Coast Guard and commercial experience.

When are those times? The only thing I can possibly think of is a wet cave situation where decoing at 20ft is impossible for some reason.

 

[MXGratefulDiver]

Well, NAUI Tech standards are 100% O2. Talk to Mr. Weinke about

Yes, I know ... he taught me to standards, then offered his personal opinion as simply that ... based on his experiences.

When are those times? The only thing I can possibly think of is a wet cave situation where decoing at 20ft is impossible for some reason.

The situations he offered were those where there are considerable waves or swells ... or a deco along walls or pinnacles where downcurrents are common.

Beyond the increased deco time, what are the disadvantages? I mean, at 80% the PN2 levels are significantly less than what we're breathing from the atmosphere at the surface. I understand the (obvious) advantage of no N2 at all during the shallow stops ... but isn't this really more an efficiency issue than a safety issue? And is that extra few minutes you'll need for your 10-foot stop really all that important?

... Bob (Grateful Diver)

 

[Gil57usa]

I often dive 30% nitrox to 120 ft. to extend bottom time. I carry a stage bottle of 40%. This allows me to go on my deco gas at 80 ft. It sure does shorten my deco times.