Spare Air: some thoughts

[Blackwood]

Personally I don't believe this is a good idea for the new diver. Someone gave themselves an AGE in Ontario several years back by doing just this, too close to the surface. Using breathing should not be the way you control your buoyancy.

Shallow breathing leads to CO2 excess because of the lack of lung ventilation. Filling the lungs can may lead to air embolism. It's ok when your deep, but to your point, this is the Basic SCUBA thread. It's just bad practice for a new diver near the surface.

You don't teach basic SCUBA, right?

If you did (or if you do), how would (do) you teach students to ascend? Hitting the inflator button or kicking while humming?

How about descending?

How does filling the lungs lead to air embolism? If you are breathing in, your airway is open.


And regarded the bolded statement... do you believe that is true for all divers? Or just new divers? And when does that paradigm shift?

 

[DCBC]

You don't teach basic SCUBA, right? If you did (or if you do), how would (do) you teach students to ascend? Hitting the inflator button or kicking while humming?

Yes Sir I do. I teach my students to maintain neutral buoyancy at the safety stop, when they are ready to ascend, they face their buddy using him/her as a reference, drop the air in their BCs and slowly kick to the surface, breathing normally. When they are at the surface, they should be neutrally buoyant (at the end of the dive), but they're instructed to add air to their BC to insure positive buoyancy. I was taught this procedure as a Navy Diver and it has worked well for me over the years.

How about descending?

Students are weighted to be slightly negative buoyant at the surface at the beginning of the dive. Once instructed to descend, they again face their buddy and start to slowly deflate their BC. I have them stop at about 10-15 feet and obtain neutral buoyancy. They descend in steps (the same way as they ascend). Buoyancy control is critical.

How does filling the lungs lead to air embolism? If you are breathing in, your airway is open.

When you are breathing normally, you do not have to worry as long is your ascent rate is slow. If you do a positive buoyant ascent and you take a breath in near the surface, you may suffer from AGE. The variables are your ascent rate, depth and your breathing cycle. If you top-out your lungs and ascend near the surface... air embolism. A 4 ft ascent is all you need with full lungs. I know of a Navy Diver who suffered AGE because he was positively buoyant and he was in the process of sneezing. Think about it.

And regarded the bolded statement... do you believe that is true for all divers? Or just new divers? And when does that paradigm shift?

My focus was on new divers because of where this thread is. Generally speaking, I don't need to use breath control to achieve neutral buoyancy. I see that on a reef, taking photos with a bit of current, the technique can be beneficial. However "thinking" your breathing process can lead to inadequate ventilation. I don't think that recreational divers appreciate the hazards of CO2. As a working diver, proper ventilation is absolutely critical at depth.

 

[idocsteve]

Being critical of a choice of words, for whatever reason that choice was made, is entirely appropriate. The common vernacular of "hold your breath" in the english speaking world is to fill the lungs with air and seal them off. What is important is the message that choice of words would convey to the uninitiated who will cruise this forum.

Thank you for your input, especially the part that I emphasized in bold.

Of course your post echos my sentiments exactly.

From the article:

http://seaduction.com/lessons-for-life/2010-01-diver-down-choking.html

"Consider using a completely redundant air source. This is the ultimate in self rescue and it works even with a first-stage failure or in an out-of-air situation. "

The article makes reference to an alternate airsource, that's true, but

1- A Spare Air in particular is not mentioned
2- A redundant air source would not have helped the panicked diver in this situation who failed to utilize available airsources

Reg said it better:

None of this suggests a SpareAir or Pony is a bad idea. But I do think this incident is a poor example to use when advocating one.

Regarding the "holding your breath" topic:

There are many misnomers and inaccuracies in dive education.

One of the great things about this forum is that those misnomers and inaccuracies are publicly corrected, such that the casual "n00b" reader can (finally) get the right idea.

That doesn't mean that posting inaccuracies are acceptable, and it does support the idea that they should be challenged by other divers who know better, so as to present new divers from making what would be a potentially fatal error. Whats even worse is when "friends" of the diver posting the inaccuracy defend his posts, for the wrong reasons.

Examples:

Your point is well taken. I liken the whole "never hold your breath" thing to being more about making things clear to the new dive student; people who essentially have a childlike level of naivete/understanding of scuba, regardless of age or intelligence.

It`s not absurd. There is a difference between holding a breath and not-breathing having the airway open. You can be not breathing and still not holding the breath.

 

[Blackwood]

Yes Sir I do. I teach my students to maintain neutral buoyancy at the safety stop, when they are ready to ascend, they face their buddy using him/her as a reference, drop the air in their BCs and slowly kick to the surface, breathing normally. When they are at the surface, they should be neutrally buoyant (at the end of the dive), but they're instructed to add air to their BC to insure positive buoyancy. I was taught this procedure as a Navy Diver and it has worked well for me over the years.

Students are weighted to be slightly negative buoyant at the surface at the beginning of the dive. Once instructed to descend, they again face their buddy and start to slowly deflate their BC. I have them stop at about 10-15 feet and obtain neutral buoyancy. They descend in steps (the same way as they ascend). Buoyancy control is critical.

Those are the initial descent and the final ascent, which is adequate for perfectly square profiles.

What about during the course of a multi-level dive?

Swimming along a reef and a coral head plateau juts out 10 feet above you. Do you rotate, face your buddy, dump air, kick up, rotate flat once you reach the top, add air to achieve neutral buoyancy, kick across, rotate, face your buddy, deflate, rotate flat again at the bottom and add air?

Personally, I'd do it using breath control.

When you are breathing normally, you do not have to worry as long is your ascent rate is slow. If you do a positive buoyant ascent and you take a breath in near the surface, you may suffer from AGE. The variables are your ascent rate, depth and your breathing cycle. If you top-out your lungs and ascend near the surface... air embolism. A 4 ft ascent is all you need with full lungs. I know of a Navy Diver who suffered AGE because he was positively buoyant and he was in the process of sneezing. Think about it.

A sneeze is different. If you are breathing normally,out or in, the airway is open (which you acknowledge above in describing how you teach students to ascend).

 

[Blackwood]

That doesn't mean that posting inaccuracies are acceptable, and it does support the idea that they should be challenged by other divers who know better, so as to present new divers from making what would be a potentially fatal error. Whats even worse is when "friends" of the diver posting the inaccuracy defend his posts, for the wrong reasons.

Agreed.

BTW, I don't know Thal personally. By observation, though, he's one of the most experienced divers on the boards, and I respect his opinions even though I don't always agree with them..

DCBC as well.

 

[DCBC]

Those are the initial descent and the final ascent, which is adequate for perfectly square profiles. What about during the course of a multi-level dive?

Swimming along a reef and a coral head plateau juts out 10 feet above you. Do you rotate, face your buddy, dump air, kick up, rotate flat once you reach the top, add air to achieve neutral buoyancy, kick across, rotate, face your buddy, deflate, rotate flat again at the bottom and add air? Personally, I'd do it using breath control.

Perhaps I'm not clear as to your question (sorry but your last paragraph confused me a bit). Obviously, buoyancy poses the greatest challenge near the surface. I teach my "basic divers" to ascend and descend in stages together as a buddy team. The main focus of this to control buoyancy and have the student mindful of this.

When I ran a charter boat, I saw many new divers whom I hadn't trained have incredible buoyancy problems (I'm sure you have seen this as well). Divers descending and almost burying themselves in a mud bottom. Others going too deep before they got their buoyancy under control, or not being able to stop at a safety stop because of too much buoyancy and being on the surface before they could get a handle on it.

Once a diver is "in-touch" with his/her buoyancy, it's normally not a concern. I teach in steps; allowing them to develop their skills sequentially. Anyway, it seems to work for me.

A sneeze is different. If you are breathing normally,out or in, the airway is open (which you acknowledge above in describing how you teach students to ascend).

Breathing normally is fine as long as you are not screaming to the surface in a positive buoyant ascent. If so, you may have a problem. Between the time that you breath in, top-out your lungs, to the point when you start to exhale, how far have you ascended? If this coincides with a depth of 4FSW and the surface, you may already have an air embolism. In this, ascent rate plays an important part. That's all I'm saying.

I'm bad. We tend to drift off the topic of Spare Air.

 

[muddiver]

I'd say that it is a good skill to have in most cases for non-ceiling dives.

Your having a discussion over terms posted by a high school student that might not be certified in scuba diving. This has been identified in another thread because someone checked Atomic Diver's (self created) Public Profile and the information supports this theory.

Therefore, the statment "hold one's breath while ascending" should probably considered a mis-statement due to ignorance.

 

[idocsteve]

I don't know Thal personally. By observation, though, he's one of the most experienced divers on the boards, and I respect his opinions even though I don't always agree with them..

Experience does not necessarily equate to good teaching, which requires the ability to convey thoughts, facts, and ideas clearly and to account for whomever might be in the "classroom" whether it's an internet forum or a school building.

Almost as importantly is the ability to "swallow one's pride" and admit when a mistake has been made, rather than defending it.

 

[Blackwood]

I'm bad. We tend to drift off the topic of Spare Air.

Maybe, but this topic isn't "spare air," it's how personal experience and perspective colors discussion (in this case OF spare air, but that's hardly significant IMO).

Experience does not necessarily equate to good teaching, which requires the ability to convey thoughts, facts, and ideas clearly and to account for whomever might be in the "classroom" whether it's an internet forum or a school building.

Of course not.

And that's sorta my point. It is my non-professional opinion that much of the information in basic dive eduction is chosen because it's easy to convey, even though it may not be accurate or helpful.

 

[Thalassamania]

This is absurd.

Divers reading the post I quoted above, I urge you to please, please disregard the words that have been written there, they are in direct opposition to the cardinal number ONE rule of scuba diving.

Never EVER hold your breath!

Gee ... I thought the cardinal rule was, "never dive with strokes."

Actually we never use the phrase, "Never hold your breath;" rather we have always said, "keep your airway open at all times." Our phrase is clear, not open to misinterpretation and stated in the positive, rather than the negative.

Interesting "Lessons for Life" makes a case for spare air:

Seaduction - Diver Down: Choking on It

This is something that has happened to just about every experienced diver that I know, I find it hard to believe that with all the options available it either makes someone panicky or makes a topic worthy of such attention, a simple warning should suffice.

Yes there's a difference between not breathing and having the airway open versus holding your breath.

That's why one procedure is called "not breathing while having the airway open" and the other is called "holding your breath". If your airway is open, but you are not preventing the outward flow of air from your lungs, then you are not holding your breath, you are simply "not breathing".

Try the phrase that we always use, "keep your airway open at all times."

Experience does not necessarily equate to good teaching, which requires the ability to convey thoughts, facts, and ideas clearly and to account for whomever might be in the "classroom" whether it's an internet forum or a school building.

Almost as importantly is the ability to "swallow one's pride" and admit when a mistake has been made, rather than defending it.

Good teaching means phrasing in the positive, without any possibility of the kind of confusion that the phrase you favor might bring about in stupid people who lack judgment. I apologize profusely for overestimating your capabilities ... it will happen again.