Agree more diving will improve performance, however thinking and understanding the mechanism of how things go is a good thing that helps one to respond to any emergency if he knows how things work.
Breathing and buoyancy
- Thread starter Thanshin
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I hope this was not the image I was giving. Nothing is done in extremes, just small adjustments in patterns have noticable but gradual results.
It all comes with experience, and having fun underwater without over complicating things.
ScubaSteve
Wow.....what a DB
You're an engineer right? Just guessing as I'm one too so while your question may seem odd to some, it isn't to me. It's just how our brains work and I'm familiar with V=Vo + 1/2 at^2 (LOL) I'm far, far, far from an expert but let me try to explain the same thing the others said above in a way our minds work. This is the way it was explained to me.
Because things take time to happen in water there is a hysteresis between lung volume change and ascent/descent. You can use a lung change like deeper exhale or inhale to make a depth change but when you breath normally you will only "just start" to rise before you begin exhaling and "just start" to sink before inhaling again. Thus your normal breathing may make you go up and down "just a bit" but not really enough to affect your buoyancy. If you try and "breath right" by adjusting your breathing rate and depth you're bound to mess it up and by simply diving more you'll find it just comes naturally. Same thing on land - sit there and think about breathing, it won't take long until you start to feel "weird" or yawn, etc.
Because things take time to happen in water there is a hysteresis between lung volume change and ascent/descent. You can use a lung change like deeper exhale or inhale to make a depth change but when you breath normally you will only "just start" to rise before you begin exhaling and "just start" to sink before inhaling again. Thus your normal breathing may make you go up and down "just a bit" but not really enough to affect your buoyancy. If you try and "breath right" by adjusting your breathing rate and depth you're bound to mess it up and by simply diving more you'll find it just comes naturally. Same thing on land - sit there and think about breathing, it won't take long until you start to feel "weird" or yawn, etc.
captain
Contributor
Incorrect, lung volume does not change with depth. It is possible to use lung volume to control buoyancy at any depth. It was done that way before BC were invented. Naturally if you are wearing a wet suit that compresses and loses buoyancy as you go deeper you will reach a point where lung volume alone will not be enough to provide enough buoyancy to maintain a neutral state.
Am an engineer and this way makes me understand better
this requires a thought, I had the notion it was both issues, losing positive lift from your compressed wetsuit makes you feel more heavy and need more volume to compensate for. On the other hand your lung max volume at surface is not the same max volume at 10m, as pressure increases the volume will tend to decrease, or am I missing something?
In normal respiration there is more time spent in exhalation than in inhalation. Of course we can and do change this temporarily to adjust our buoyancy during a dive as we need to. To rise up over a structure and then descend back to the prior level, I may temporarily breathe with relatively more air in the lungs. In doing this, I am consciously making a change. As others have said, at all other times one should just breathe normally.
You're comments are dead on: it ain't that hard unless you overthink it.
Am an engineer and this way makes me understand better
this requires a thought, I had the notion it was both issues, losing positive lift from your compressed wetsuit makes you feel more heavy and need more volume to compensate for. On the other hand your lung max volume at surface is not the same max volume at 10m, as pressure increases the volume will tend to decrease, or am I missing something?
It's not a closed system. On SCUBA you're breathing gas at ambient pressure.
it_mike
Contributor
You missed the focus of volume in your question. Your lung max volume is consistent. The volume of air that can fit into that space changes with depth due to air density (result of increase in pressure / equalization). Your lung capacity did not change, the air pressure in your lungs changes to equalize to off-set the water pressure at depth.
Mike
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