Any Tips on Conserving Air?

[BOHUNTER]

LP 108

Happy Diving

 

[Lobzilla]

first.. do all the other things that have been suggested.

After that mentally prepare yourself and get a breathing rhythm as soon as possible (just like at the street light on your way to the dive) sip air in for a count of five, then breath out for a count of five, once comfortable add one more count in and out. If you can count six in and six out - that should equate to about a 60 minute dive at say 55 feet average depth, as you dive more try to increase by one count and before you know it you will be 10 in and 10 out. NO SKIP BREATHING? it defeats the purpose. if you lose your rhythm and need to take a couple big breaths...no big deal, just restart when you can. using this technique will have you feeling a little air starved initially, but will pass with more practice.

<snip>
good luck

Now I have a question:

The breathing pattern described above would change your buoyancy constantly as the air volume in your lungs is never at rest. It also would show a 6 to 10 seconds stream of bubbles on the exhale.

When I watch videos of the 'kings of buoyancy control' I do not see this pattern. I see a relatively short burst of massive bubbles followed by a relative long pause. I assume they pause at the volume that makes them neutral and then do a relatively short but deep exhale and inhale to the same volume.

Can someone shed light on this mystery?

 

[TSandM]

Using abnormally large tidal volumes at very slow respiratory rates will result in larger buoyancy swings. I think most of us who have gotten buoyancy control down to a matter of inches have learned to cycle a slightly larger tidal volume than that used when on land, around a center lung volume, at a rate where, by the time inertia has been overcome and the body is beginning to move, the lung volume has changed enough to damp the excursions.

Edited that any breathing pattern that leaves you feeling air-hungry is trying to tell you that it's not clearing CO2 effectively.

 

[Bubbletrubble]

Now I have a question:

The breathing pattern described above would change your buoyancy constantly as the air volume in your lungs is never at rest. It also would show a 6 to 10 seconds stream of bubbles on the exhale.

When I watch videos of the 'kings of buoyancy control' I do not see this pattern. I see a relatively short burst of massive bubbles followed by a relative long pause. I assume they pause at the volume that makes them neutral and then do a relatively short but deep exhale and inhale to the same volume.

Can someone shed light on this mystery?

When you're at a given depth and neutrally buoyant, you'll notice that you rise and fall in the water column as you inhale and exhale, taking normal breaths. You'll also notice that there's a certain amount of time lag between inhalation and rising (or exhalation and falling). With practice, you can time your exhalation/inhalation to work with this time lag in breathing buoyancy changes in order to maintain your position in the water column...all while using a "normal" breathing cycle (inhale, slight pause, exhale, slight pause). Practice it enough and you can do it without even thinking about it.

[Edited later: I see that TSandM just beat me to the punch. ]

 

[Lobzilla]

Using abnormally large tidal volumes at very slow respiratory rates will result in larger buoyancy swings. I think most of us who have gotten buoyancy control down to a matter of inches have learned to cycle a slightly larger tidal volume than that used when on land, around a center lung volume, at a rate where, by the time inertia has been overcome and the body is beginning to move, the lung volume has changed enough to damp the excursions.

From a physiological standpoint, how long could/should you pause between these rather short gas exchanges? Also, the surface nose-breather pattern does not seem to have a significant pause. So, in essence skilled divers are not breathing 'normally' in terms of landlubber standards.

 

[Bubbletrubble]

From a physiological standpoint, how long could/should you pause between these rather short gas exchanges?

How long do you pause between inhalation and exhalation while breathing "normally" on land?

 

[UseMyLungs]

I need to relax more.

 

[TSandM]

No, scuba breathing is not like breathing on land. On land, you're not trying to make the most efficient use of the air you have -- you actually breathe in a fashion that minimizes work of breathing instead. (It doesn't matter if you spend a significant amount of the volume you breathe in a minute on exchanging dead space, so long as enough gets to the alveoli, because your supply is unlimited.) Underwater, you use a breathing pattern which has a slightly higher work of breathing, but makes more efficient use of the gas supply, by reducing respiratory rate and increasing tidal volume. There is a practical limit to this, based on both diver comfort and buoyancy control, but scuba breathing more closely resembles yoga breathing or meditation than normal land breathing.

As far as the length of the pauses, they're going to be related to required minute ventilation and to buoyancy control. You HAVE to run a certain volume through the lungs per minute to keep CO2 normal -- if you are spending part of that minute not moving air, then you have to move air more rapidly during the remaining part of the minute to meet your volume goal. At some point, doing that is going to become very uncomfortable. In addition, overly long pauses WILL result in depth excursions.

It's easy to overthink this. If you simply practice hovering, you will gradually discover the breathing pattern that keeps you comfortable and results in a steady position in the water column. It will be a slightly slower, slightly deeper breath than on land, with a short pause at end inhalation and end exhalation (I think mine are about a count of two, just sitting here and trying to model it at my kitchen counter.)

 

[Bubbletrubble]

No, scuba breathing is not like breathing on land. On land, you're not trying to make the most efficient use of the air you have -- you actually breathe in a fashion that minimizes work of breathing instead. (It doesn't matter if you spend a significant amount of the volume you breathe in a minute on exchange dead space, so long as enough gets to the alveoli, because your supply is unlimited.) Underwater, you use a breathing pattern which has a slightly higher work of breathing, but makes more efficient use of the gas supply, by reducing respiratory rate and increasing tidal volume. There is a practical limit to this, based on both diver comfort and buoyancy control, but scuba breathing more closely resembles yoga breathing or meditation than normal land breathing.

@Lobzilla: It's worth mentioning that depth and reg tuning (in addition to other reg features) will figure into work of breathing.

FWIW, I find that my pauses while breathing underwater are very similar to my pauses while breathing on land.

Novice divers just need to dive more. When they finally get comfortable and stop focusing on their breathing so much, they'll realize that their gas consumption has gone down significantly.

 

[Lobzilla]

@Lobzilla: It's worth mentioning that depth and reg tuning (in addition to other reg features) will figure into work of breathing.

FWIW, I find that my pauses while breathing underwater are very similar to my pauses while breathing on land.

Novice divers just need to dive more. When they finally get comfortable and stop focusing on their breathing so much, they'll realize that their gas consumption has gone down significantly.

I dive SP G250s with either Mk25s or Mk17s upstream. The G250s are tuned on the light end of the cracking pressure tolerance. (backup reg is detuned via external adjustment screw until I breathe it). I dive as horizontal as possible. If there is another trick to reduce WOB I would love to hear it.

Gas consumption is not my problem. I typically hit NDL or 'frozen my rear end off' before the SPG calls the dive (with rock bottom gas planning).

The reason why I engaged in this thread is that there is always the suggestion to just breathe 'normally'. Singers do not breathe normally, trumpeters do not breathe normally, Yogis do not breathe normally, and as videos suggested and TSandM confirmed, divers do not breathe 'normally' either. Anything not normal has to be learned one way or the other. It can be learned either by accident or through conscious effort.

I have found so far two patterns that work if I want to measure buoyancy deviations in inches. One is a relatively shallow swing around the volume that gives me neutral buoyancy.(As TSandM pointed out, not very good for CO2 clearance). The other is pause at neutral buoyancy volume and exhale/inhale somewhat deeper and faster. You can see both patterns here. Keep in mind that this was a working dive; working on skills and drills. It came out to a RMV of .62 cf/min over the course of an hour. Half a year ago, I was at 1. something. I am confident that .5 ish is feasible for me.

However, I also know someone who's RMV starts with a .3 no matter what she does. Any tank she takes as a single I will have to take as doubles - that's the grim reality.