Neutral Buoyancy and Breathing

[ccrprospect]

Hello,

During OW and AOW classes, I was advised to breathe slowly and deeply- i.e. I take in a full breath of air as slowly as possible, and then exhale fully, also as slowly as possible. This advice was given in response to my initially rapid air consumption (which did improve after shifting to the deep breathing technique described).

The problem is it is hard to maintain my position in the water column consistently using that breathing technique - I always rise and fall with each deep inhalation/exhalation even if not significantly. Where it becomes problematic is when navigating in semi-open cavern like environments or if swimming close to the sea bed, where in both cases I almost invariably bump into the surroundings. Even on the safety stop, my computer keeps on registering rises/falls of 2-3 feet continuously thanks to my breathing technique.

One of the divemasters I recently dived with advised instead to breath "as if sucking from a straw" to prevent those bouyancy fluctuations.

What would be your advice?

Thanks

 

[bl6394]

Your lungs displace approximately six pounds of water - when fully inflated. Assuming your are neutrally buoyant - at mid-breath. When you slowly and fully exhale - you will apply a negative force that will peak out at 3 pounds. Let's imagine that you exhale over a count of say 8 seconds. The application of force over time must and will cause you to sink - assuming you are not counteracting the change in the water column with your trim, hands or feet. Likewise - slowly and fully inhaling will create a positive buoyant force - causing a brief rise in the water column. Your net change in the water column is zero - but you don't like the oscillations in depth.

Assuming your are relaxed and not overexerting yourself - such as when you are sitting at a desk reading this - you are probably not exaggerating your breathing - fully inhaling and fully exhaling. Having a more relaxed and natural breathing style will minimize the natural oscillations that result from inhaling and exhaling that I described above.

I don't recommend breathing as if you are sucking from a straw. This sounds pretty uncomfortable - and does not address the physics of why you are rising and falling in the water column. Displacing less water - ie having a smaller respiratory tidal volume - and doing so without an exaggerated lag on either the inhalation or exhalation will minimize your changes in the water column as a function of breathing.

Relax and breath normally! Your gas consumption will naturally improve as your comfort in the water increases.

 

[NorCalDM]

Breathe normally! You can use your breathing to adjust your position in the water colum but there is no trick to it follow your normal breathing pattern. Your air consumption will also get better if you get your weighting dialed in so you use little to no air in your BC.

 

[diver0008]

Different breathing styles for different situations. Like finning.

If you are just cruising along looking at the scenery, then a nice slow and deep breathing style is great, in sync with a smooth frog kick. Your forward motion will offset buoyancy vectors.

If you are trying to get close to something, stay still, or get through something, then a shallower breathing style is necessary to avoid unwanted depth changes, and of course the finning style may also differ according to what your task is.

 

[ScubaInChicago]

Your lungs displace approximately six pounds of water. Assuming your are neutrally buoyant - at mid-breath. When you slowly and fully exhale - you will apply a negative force that will peak out at 3 pounds. Let's imagine that you exhale over a count of say 8 seconds. The application of force over time must and will cause you to sink - assuming you are not counteracting the change in the water column with your trim, hands or feet. Likewise - slowly and fully inhaling will create a positive buoyant force - causing a brief rise in the water column. Your net change in the water column is zero - but you don't like the oscillations in depth.

Assuming your are relaxed and not overexerting yourself - such as when you are sitting at a desk reading this - you are probably not exaggerating your breathing - fully inhaling and fully exhaling. Having a more relaxed and natural breathing style will minimize the natural oscillations that result from inhaling and exhaling that I described above.

I don't recommend breathing as if you are sucking from a straw. This sounds pretty uncomfortable - and does not address the physics of why you are rising and falling in the water column. Displacing less water - ie having a smaller respiratory tidal volume - and doing so without an exaggerated lag on either the inhalation or exhalation will minimize your changes in the water column as a function of breathing.

Relax and breath normally! Your gas consumption will naturally improve as your comfort in the water increases.

Not to nitpick, but it's Archimede's principle where the chest cavity is expanding displacing more water, hence making you more buoyant. Yes the lungs help in this process, but so does being stressed/tense and increasing volume. I'm sure you've heard you can shed more weight from your weight belt when you're calm and relaxed.

As for breath control to the OP, try keeping between 25-75% of total tidal volume for normal relaxed breathing and the final top/bottom 25% to initiate movement in the water column.

 

[Neilwood]

Hello,

During OW and AOW classes, I was advised to breathe slowly and deeply- i.e. I take in a full breath of air as slowly as possible, and then exhale fully, also as slowly as possible. This advice was given in response to my initially rapid air consumption (which did improve after shifting to the deep breathing technique described).

The problem is it is hard to maintain my position in the water column consistently using that breathing technique - I always rise and fall with each deep inhalation/exhalation even if not significantly. Where it becomes problematic is when navigating in semi-open cavern like environments or if swimming close to the sea bed, where in both cases I almost invariably bump into the surroundings. Even on the safety stop, my computer keeps on registering rises/falls of 2-3 feet continuously thanks to my breathing technique.

One of the divemasters I recently dived with advised instead to breath "as if sucking from a straw" to prevent those bouyancy fluctuations.

What would be your advice?

Thanks

I would say the issue you are having is more related to timing than anything else. Assuming you are correctly weighted & have the correct amount of air in your BCD for the depth, your breathing will swing you up and down past the midpoint.

Within a few seconds of starting to inhale, you will start to head up. Similarly when you exhale, you will start to drop. The trick is recognising the point at which momentum shifts and timing the inhalation to arrest the downwards momentum and vice versa for the exhalation.

Best plan I would suggest is to get in a pool (buoyancy is harder to maintain nearer the surface so if you practise in a relatively shallow pool it will fine tune your performance more quickly as the swings are more magnified). Pick a mark out on the side of the pool (paint, grout line, wax crayon if allowed etc) as your "centre point" and get yourself set up so at mid breath you are in line with the point. Start breathing in watching for when you start to climb and then exhale which slowly will arrest the rise and start you falling. You then start to inhale slowly which arrests the downward momentum and so on. Given that the momentum swing takes a few seconds, you should be able to get a decent breath in and out in that time. With a bit of practise you should be able to hold within 1ft either way and possible less with more effort.

 

[Diving Dubai]

All righty..

Let's discuss a normal breath. Under water newer divers tend to exaggerate breathing, normally breathing in too deeply - but we'll come back to that.

First you need to be able to visualise your lungs. Think of a fuel gauge on a car. The normal breath is between 1/4 empty and 3/4 full. the center point where you're perfectly neutral is the 1/2 full point.

Breathing should be a rhythm, I teach the mantra of counting calmly such as:

Breathe in, 2...3...4, Hold 2...3...4, Exhale 2...3...4 Nice slow and calm.

The next question is are you really neutral? You may think so....

Normally when approaching the bottom people take a deep breath while adding air, this is fine if you exhale again. unfortunately most don't so they end up breathing in the top half of their lungs and adjusting their buoyancy from there. The body and brain is very good at being accustomed to this and ignoring it. A bit further into the dive you relax, go back to a normal breath and find yourself in the sand.

Also the body has a fight or flight reflex. In times of stress or anxiety your diaphragm drops to increase your lung volume making you more buoyant. This happens subconsciously.

No doubt you've been taught that if you're lifting a weight off the bottom (say 2.5kg) you inhale more to compensate, and when you put it down you exhale again to compensate.

So as you are adding air to your BC near the bottom to establish buoyancy, exhale a bit too when you get it right you should remain stationary.

Having too much lead will exacerbate things.

I don't go for the "drinking through a straw method" - well unless say you're into a current and breathing deeply. In my case I de tune my reg, but you can breath around your tongue (using the tip to restrict not block off the mouth piece) just to calm your breathing down and stop hyper ventilating.

Try these blogs. also

Buoyancy master class week 1

Buoyancy master class week 2

Buoyancy master class week 3

Buoyancy tips

Fine tuning Buoyancy

None of them written by me, but a great source of info and practice tips

 

[bl6394]

Not to nitpick, but it's Archimede's principle where the chest cavity is expanding displacing more water, hence making you more buoyant. Yes the lungs help in this process, but so does being stressed/tense and increasing volume. I'm sure you've heard you can shed more weight from your weight belt when you're calm and relaxed....

Yup - you're nitpicking.

 

[Andreas Krueger]

I advice to breathe normal. Get a bigger tank if you feel like your air consumption is cutting your dives short. If you are diving with Aluminum 80 (10 liter) consider getting a steel 100 (12l) or even steel 120 (15l). That will take care of the air consumption problem and you can focus on other diving skills.

 

[ScubaInChicago]

Yup - you're nitpicking.

I've been called worse see you at next year's NSS-CDS Conference