Is this bad?

[shakeybrainsurgeon]

I hate to barge in on an esoteric discussion of air consumption, but my question remains unanswered: what did everyone start with?? When I certified, half the class had al80s and half had steel 72s. Thus, some started at over 3000 psi and others at 2200. This would explain such a massive difference in remaining air (500 vs 2200???? come on). Before we start comparing the basal metabolic rates of people or gushing over someone's air use, how about knowing how much air WAS used by everyone. To do that, we need two data points for all involved, not one. If that data is in this thread, I missed it.

 

[shellim123]

Everyone started with 3000-3200

 

[shakeybrainsurgeon]

Everyone started with 3000-3200

fair enough...let the debate rage on, then

 

[joe rock]

I hate to barge in on an esoteric discussion of air consumption, but my question remains unanswered: what did everyone start with?? When I certified, half the class had al80s and half had steel 72s. Thus, some started at over 3000 psi and others at 2200. This would explain such a massive difference in remaining air (500 vs 2200???? come on). Before we start comparing the basal metabolic rates of people or gushing over someone's air use, how about knowing how much air WAS used by everyone. To do that, we need two data points for all involved, not one. If that data is in this thread, I missed it.

Actually Shakey, we need four. Rated tank pressure, begining tank pressure, ending pressure and tank volume.

 

[TSandM]

I dove with a novice diver whose SAC rate was about 1.8. Mine is around .4. That'll give you that kind of difference.

 

[shakeybrainsurgeon]

Actually Shakey, we need four. Rated tank pressure, begining tank pressure, ending pressure and tank volume.

Correct, but we can presume that all students in a class would have at least similar tanks if they were starting with around 3000 (AL80s most likely). The difference in usage may also be attributable to buoyancy control issues, or to some people letting their alternate air sources free flow accidentally, or to leaks. I just don't see physiologic factors alone explaining why one person uses 800 psi for a dive and another using 2500 for the same dive, unless some people were breathing like a steam engine. There are likely other reasons non-physiologic factors (overusing the bc) as to why some people are exhausting their tanks.

But the original question "is this bad" strikes me as sort of tongue in cheek. Underusing air is bad only if you surface belly up like my childhood goldfish. Anyone who dives and then lives to post a scubaboard thread could not have underutilized his tank. It's like asking --- "I went to Europe and had a great time, but came back with 3000 dollars more than any of my companions, some of whom were broke--- did I do something wrong?"

 

[Tigerman]

"I went to Europe and had a great time, but came back with 3000 dollars more than any of my companions, some of whom were broke--- did I do something wrong?"

You sure as hell did!! Go back there and spend more money!

 

[shakeybrainsurgeon]

You sure as hell did!! Go back there and spend more money!

My point exactly Tigerman --- if I started with 3000 and came up with 2200, I'm looking for someone else with air and going back down! Why waste a nearly full tank of air?

And, having just come back from Aruba and its casinos, I really didn't have a problem with being overburdened with cash on the way home from there either.

 

[TSandM]

I know . . . It used to annoy me no end to take a tank with 1500 psi in it and pay full freight for a fill. Nowadays, I have the "all the Nitrox you can use" plan, and I don't mind any more.

The best thing is that with these lovely new 85s I have, I can apparently quite often get THREE dives out of them before I have to head for the dive shop for a fill. There really are huge advantages to being little. Carrying the gear, however, is not one of them.

 

[1_T_Submariner]

As many have said air consumption depends on many things. Your are very fortunate to start with a low consumption rate. I have a buddy that was like this when we started diving together. I would come up change tanks go for another and he would just finish the tank he was on. We are about the same now. His air consumption hasn't changed and I have caught up to him.
Just keep diving....