Spare Air: some thoughts

[Thalassamania]

Not if you teach them how to do it properly... which was the point, as I'm sure you knew.

He's just a troll who confuses yapping at the heels with running with the big dogs.

 

[idocsteve]

Not if you teach them how to do it properly... which was the point, as I'm sure you knew.

There is no proper way to hold your breath while Scuba Diving.

Keeping the airway open is another matter entirely but the operative word is "hold" which means to "stop from moving".

That's just wrong, at the very least it's a very poor choice of words on a forum frequented by new divers looking for advice. It's completely unacceptable especially coming from an instructor. Of course insulting those who disagree is also not something a quality instructor might do... but that is stating the obvious.

 

[Web Monkey]

Anybody that can't plan and execute a safe dive and maintain good buddy distance probably shouldn't be diving anyway.

I don't know what to say to this Terry. It's either that you haven't been diving that long, or you've been very fortunate.

I've only been diving for about 10 years. And although I've been "fortunate" in that I haven't died or been injured, I attribute it to following my training, not carrying a SA. As mentioned above, I don't need a SA on shallow dives, and bring an appropriate sized redundant airsource on deeper dives. When the brown stuff hits the fan, I do as I was trained, which has, so far, proven to be useful.

In fact, at the risk of airing dirty laundry, I'll even list my screwups/problems and how they were handled. You'll notice that none required a SA.

Problem: Inflator hose tore off BC on a wall dive resulting in loss of buoyancy.
Solution: Ascend, ditch weights on the surface and wait for boat. I wasn't overweighted, so swimming up wasn't a problem.

Problem: Got tangled in line on bottom of lake, with no cutting tool.
Solution: Buddy untangled me.

Problem: Regulator freeflowed in 34 degree water.
Solution: Did normal ascent and ended dive.

I've never run out of air, although my buddy and I do OOA drills all the time.

I can't believe that you feel that a diver should only dive if he and his buddy are infallible; ot that he is in full control of everything that can happen to them. Speaking for myself, I certainly can't. I have to say that I'm pretty well trained and have gone OOA. Do I fall into the category of someone who shouldn't be diving as far as you're concerned?

I'm pretty sure you don't fall into the category of "Can't plan and execute a safe dive", and I don't beleive anybody is infallible.

However I also beleive that all the items listed in the "Buy a spare air" list can be eliminated with training, a buddy, good judgement, proper maintenance and if necessary an additional properly sized redundant air source.

Terry

 

[Blackwood]

Keeping the airway open is another matter entirely but the operative word is "hold" which means to "stop from moving".

Consider how we breathe. We contract our diaphragm to inhale, and relax it to exhale.

If you keep your diaphragm contracted, you keep that negative pressure applied, and regardless of the state of the airway or what happens when the volume in your lungs increases (as in the case of a diver ascending), you are holding your breath.

BTW, as you are reading this: hold your breath.


Did you close your airway? I didn't.

 

[idocsteve]

Consider how we breathe. We contract our diaphragm to inhale, and relax it to exhale.

If you keep your diaphragm contracted, you keep that negative pressure applied, and regardless of the state of the airway or what happens when the volume in your lungs increases (as in the case of a diver ascending), you are holding your breath.

BTW, as you are reading this: hold your breath.


Did you close your airway? I didn't.

I did two things

1- I sat motionless and did not voluntarily contract or expand my lungs. I simply did nothing. This keeps my airway open and would allow an external force such as a change in ambient pressure, to equalize the volume of my lungs with the external environment.

2- I held my breath by maintaining firm control with my diaphram. This would prevent the flow of air in or out by an external force that was not as powerful as that of my own muscles.

3- If I did number 2, while ascending from any significant depth, I'd most likely end up with an embolism. And no, I don't mean "number 2" as in the usual sense of bowel elimination.

 

[DCBC]

In the ANZ survey in half the deaths (56%), critical events developed when the diver was either running low or was out-of-air (LOA, OOA). When equipment was tested following death, few victims had an ample air supply remaining. The DAN survey found 41% in this situation.

http://www.divingmedicine.info/divingmedicine/Welcome_files/Ch 34.pdf

It's clear that despite the training received by diver's to-day and the fact that most diver's are not suicidal and try to dive safely, there is clearly a problem. We can pretend that it's not there, we can be self-assured as Instructors saying that "my divers never make mistakes," or we can just not care. The facts remain that divers die because they run out of gas.

We can point fingers and disparage technology that's designed to prevent such deaths, but they will not go away. I feel that it's necessary to properly train my students: tell them to stay close to their buddy, dive within their diving envelope and plan for the dive. I also advise them that there are situations where they will not be in-control and encourage them to dive with a redundant breathing system.

I also point-out that any redundant system has its limitations and a limited diving envelope. From my experience I believe there is a value to a few extra breaths of air. Perhaps this isn't appreciated by everyone, but I'm reasonably convinced that their opinion would change should they find themselves in such an emergency.

 

[DCBC]

If a new diver (not yourself) is diving within his training, do you agree that he is not in current and low visibility, is not at a depth where multiple breaths of air are necessary for a CESA, and is ending any dive where he is separated from his buddy?

Reg, when I had a Dive Charter business I saw too many divers with poor buoyancy control (some over-weighted). I've witnessed new divers descend at astonishing rates and bury themselves in a mud bottom turning the visibility to 2 or 3 feet. Sometimes it's taken several minutes to find them. When I asked them why they didn't surface having been separated from their buddy they just said that they were waiting for things to clear a bit so they could see them.

I wouldn't let most of the divers out of the pool and sure as hell wouldn't give them a card until they possessed the necessary skills. But someone did!

I'm just trying to qualify your statements so we understand what exactly we are talking about.

I am saying that should any diver find themselves requiring to do a free-ascent / CESA from beyond their FATD they have a high chance of death. If they possess a redundant source of air (RSA), most will live.

I promote a diver having a RSA for such emergencies. I do not understand why others don't. If you feel that you don't wish to, that's your call. If you choose a Pony Bottle; that's your call. If you choose a Spare Air; that's your call. I would not however make a disparaging comment towards you because of your choice.

 

[Reg Braithwaite]

In the ANZ survey in half the deaths (56%), critical events developed when the diver was either running low or was out-of-air (LOA, OOA). When equipment was tested following death, few victims had an ample air supply remaining. The DAN survey found 41% in this situation.

http://www.divingmedicine.info/divingmedicine/Welcome_files/Ch 34.pdf

Great read. I can cherry-pick support for and against SpareAir from the article. For example, it brings up panic as a major factor in 39% of the deaths. Perhaps having a SpareAir would make divers calmer. It also brings up poor buddy practices: 86% of the divers who perished did not have their buddy with them. Amazingly, failing to ditch weight was identified as a factor in 90% of the incidents!

All in all, I feel like I am learning a great deal going through the article carefully. Thank you.

 

[Web Monkey]

I also advise them that there are situations where they will not be in-control and encourage them to dive with a redundant breathing system.

Do you recommend a Spare Air, or something bigger?

 

[Reg Braithwaite]

Reg, when I had a Dive Charter business I saw too many divers with poor buoyancy control (some over-weighted). I've witnessed new divers descend at astonishing rates and bury themselves in a mud bottom turning the visibility to 2 or 3 feet. Sometimes it's taken several minutes to find them. When I asked them why they didn't surface having been separated from their buddy they just said that they were waiting for things to clear a bit so they could see them.

FWIW, when I took my AOW the LDS took us on a charter that required pony bottles for divers that were not AOW on all dives below 60'. So far they seem to be the exception and not the rule.