Why would you want to do this? If you're finning to adjust your depth, then what happens when you stop? Get neutral first. It makes everything else easy.
Controlling Buoyancy with your breath: Why?
- Thread starter Boyan
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often spells disaster for the vis. Sure, there's a time to kick up or down, but I see it being done way too often and with unintended results. Me? I like to dive with a slow fin. I'm never in a rush and I like the precision of breathing my depth changes. Slow and easy is great.
andrewy
Contributor
yep very simple. CO2 retention. If u take deep breath to keep yourself in place. your lungs will be always half empty/full depends on your beliefs 
that restricts gas exchange and u WILL get tired and out of breath and u WILL take huge gulp and wont stop and will not be able to keep position in the water. It works with singles, but try it with doubles, then add few stages .
that restricts gas exchange and u WILL get tired and out of breath and u WILL take huge gulp and wont stop and will not be able to keep position in the water. It works with singles, but try it with doubles, then add few stages .
I may be missing something, but I don't believe that being heavily overweighted provides this kind of benefit, or at least I'm not aware of any mechanism, through which this would happen (adding or removing a few pounds to a male body that on average weighs 150-200 lbs in total should not really change its inertia by such a huge amount that one would become perfectly stable). If you take a full breath, you are creating the same buoyant force, regardless of how much you are overweighted.
I strongly suspect that what has actually happened is that, as a result of the added training an experience, your standard for being "neutral" has become considerably higher, you are now able to notice more subtle changes, and you are simply being more critical of your own performance.
Yes, and this makes you go up and down considerably.
Let’s assume you are at 10 meter depth with 8kg weight on your belts. You have X amount of air at your bc. When you rise to 5 meters then your air in bc will expand to 1,5 X. So you have to empty your bc with 0,5 X air to turn back to neutral buoyancy. Yes I know this doesn’t work this much straight, you have to discharge more but this is just to give an idea.
If you are diving with 12kg weight at your belts than X amount of air will not be enough for the same diver at 10 meters, he must have 1,5 X air (again assumption not a certain number, just to give an idea) When he ascents to 5 meter than air in his BC will be 1,5 X x 1,5 = 2,25 X. This means he has to discharge 1,25 X amount of air.
Discharging 0,5 X amount of air can be controlled much more easily in a shorter time than 1,25 X amount of air. It is much safer. Also using your air in bc is a bad way of wasting precious air. This is not the only way to loose air. As you need more adjustment at your bc when you are changing your depth you need to use fins to stay at the same depth. This makes you use energy which is equal to using air.
Learning to use lungs for buoyancy doesn’t mean to have excess air in your lungs for a long period. This is just for small adjustments. Then you have to make the real adjustment with your bc. Give a normal breath, than try to give more breath. You can easily see there is still air in your lungs after you give breath normally. Try to stay neutral after you give your breath normally. If you are neutral, breathing normally will not change your depth in a sudden.
When I dive with a group with new divers that’s the only case I dive with excessive weight because I might need to bring them down when they start to rise uncontrolled. Otherwise diving with right weight saves air and it is much safer.
If you are diving with 12kg weight at your belts than X amount of air will not be enough for the same diver at 10 meters, he must have 1,5 X air (again assumption not a certain number, just to give an idea) When he ascents to 5 meter than air in his BC will be 1,5 X x 1,5 = 2,25 X. This means he has to discharge 1,25 X amount of air.
Discharging 0,5 X amount of air can be controlled much more easily in a shorter time than 1,25 X amount of air. It is much safer. Also using your air in bc is a bad way of wasting precious air. This is not the only way to loose air. As you need more adjustment at your bc when you are changing your depth you need to use fins to stay at the same depth. This makes you use energy which is equal to using air.
Learning to use lungs for buoyancy doesn’t mean to have excess air in your lungs for a long period. This is just for small adjustments. Then you have to make the real adjustment with your bc. Give a normal breath, than try to give more breath. You can easily see there is still air in your lungs after you give breath normally. Try to stay neutral after you give your breath normally. If you are neutral, breathing normally will not change your depth in a sudden.
When I dive with a group with new divers that’s the only case I dive with excessive weight because I might need to bring them down when they start to rise uncontrolled. Otherwise diving with right weight saves air and it is much safer.
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