How deep to breathe??

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SteveDiver

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I have been reading that one should breathe in very deep to one should just breathe normal...so what is it?? fill your lungs to capacity or breathe normal?
 
goofystan:
I have been reading that one should breathe in very deep to one should just breathe normal...so what is it?? fill your lungs to capacity or breathe normal?
Breath normally.
 
That is as much a bouyancy question as anything else. I practice normal breathing but more slowly at depth than at surface. Hope that makes sense. At 90 ftsw, if I take a full capacity breath, I will rise significantly in the water. My 2 cents is to breath slowly using normal size breaths. This will allow you to control your bouyancy and air usage.
 
yes, a normal breath but use your diaphragm when breathing not your upper lungs. This is evident when your stomach rises on a breath (diaphragm) or when your chest rises (chest breathing).
 
Shallow breathing needs to be avoided as the liter of air or so of air in the mouth and trachea is not going to transfer O2. So if for example a diver is only inhaling 2 liters of air per breath, he or she will only be using 1/2 of it. If on the other hand a diver inhales 4 liters of air per breath, he or she will potentially be using 3/4 of it effectively.

In normal breathing you also exhale and pause. When diving it is more efficient to pause after the inhalation rather than after the exhalation. Not to confuse this with holding your breath - you need to keep the air way open and just hold the breath with your diaphragm for the couple seconds you would normally pause when breathing on the surface.

A slow relaxed breathing cyle is important and is as big an issue as breathing deeply.
 
newbie here... i was trying to practice several techniques to breathing in the pool today for proper bouyancy, if i take slow deep breathes, both inhilation and exhilation, i tend to rise quick on the inhale so i try to dump as much air as i can on the exhale. i have an untested theory, what if you were to inhale normaly (say 2 seconds) pause then exhale for a longer duration (3-4 seconds)....would this compensate for the rise?
 
Your lungs are your "fine control BC." You want to think of them and the BC (and potentially your drysuit) as one system. Breathing normally and slowly (more effecient,) you should notice a little rise and fall, but we're talking inches. Want to come up a bit? Take a deeper breath than mormal, feel yourself rise, then exhale and resume normal breathing at your new depth. Want to descend a bit? Give the exhale a little extra "umph," hold a moment longer than usual before inhaling, then resume normal - you will have descended a bit.

Bottom line - drysuit for comfort (not squeezed but not using for gross buoyancy control,) BC for gross buoyancy control, lungs for fine control. When in balance (not descending or ascending,) normal breathing should give you a comfortable equilibrium state with little variation in depth/buoyancy.
 
Henryville hit the nail on the head. I'll just add that "holding" your breathe refers to holding it with the negative/equal pressure developed by your diaphragm muscles - you never want to do this by closing off your throat, especially when rising.

It's entirely normal and expected to rise with a full breath and sink when you exhale and a diver with ample experience and excellent bouyancy skills will automatically make his or her BC (and drysuit) bouyancy adjustments during a pause with the optimum amount of air in his or her lungs that will balance the rise and fall that results from their particular breathing pattern.

So...you can certainly extend the period where you have fully exhaled to drop a few more inches or so in a specific situation, but in general it is much easier and much more efficient to maintain your breathing cycle but just dump a very small amount of air from your BC if you find yourself rising more than you are falling. In shallow water you will also find that you need to adjust the amount of air in your BC very slightly if you change depth more than a foot or so.

My preference is to use the BC to fine tune for my average target depth and then adjust lung volume for any momentary excusions. So for example if I am crsuing a couple feet off the bottom, I want to be neutral with the exact amount of air needed to ensure I am rising and falling equally with my normal and efficient breathing pattern. Then, if I want to drop down to the bottom to check something out or pick up something, I exhale and hold it slightly longer than normal to sink the couple extra feet, then inhale to hold depth and then inhale more to rise back off the bottom and back to my target cruising depth. If the object I pick up is more than a few ounces, then obviously I am going to want to add a tiny amount of air to the BC. Further more, if I have to change depth more than a foot or two, the pauses can get uncomfortably long, requiring a quick inhale/exhale or exhale inhale, and in some cases a temporary BC bouyancy adjustment.

Another useful technique is to stay very slightly positive and then adjust your thrust angle very slightly own to keep you at a steady depth. This is very useful over a soft silt bottom where you want to stay only a few inches off the bottom and cannot afford any sink at all on exhlation. In this case, you time your kicks and use momentum to cancel out the rise when you inhale. With practice (and proper finning techniques) you will find you can hold depth an inch or two over a silty bottom and not stir any thing up at all.

Many novice divers use their thrust angle to compensate for bouyancy, but do it very badly by thrusting up at large angles to offset negative bouyancy. The constant kicking is tiring to the diver and is at best annoying to other divers as the constant movement scares fish. At worst it damages reefs or stirs up large amount of silt (which can be a safety hazard) as the diver imitates a human roto-tiller. If you use changes in thrust, use them to offset SLIGHT positive bouyancy and be sure you are doing it for a specific purpose. In general, you want to be able to stop all movement and hold your depth exactly with a more or less neutral lung volume.

In short you want to not only consider your lungs and BC or drysuit as a bouyancy system but also your trim (many divers are feet low which is very very bad) and thrust angle in the water and the effects those factors have on your system.
 
thanks for the explanations, well done...now i need to practice a bit more
 
Just to reiterate one piece of what was written above -- an excellent check that you have the right amount of air in your BC is to notice what happens at the ends of each breath -- if you aren't rising slightly at the end of an inhale, you're a little bit negative and need a touch more air; if you aren't sinking slightly at the end of exhale, you're a little positive and need to vent slightly. You can slightly prolong the pause at the end of each phase as a form of buoyancy check, and do that every twenty breaths or so, or whenever the terrain is causing you to change depth at all.
 

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