This.
Air consumption improvement
- Thread starter raskous
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This.
asj
Registered
You can lose 200 bar because the tank cools and the pressure drops. Even if the water is 25c, if the tank has just been filed, or is sitting in the sun waiting for you to go down it'll be warmer than the ocean.
Relax, don't race around, and relax. Calculate your SAC rate, then you have a number you can compare. I plan with 20l/min which is a poor number, but makes a good worse can number for a very active constantly swimming dive.
Cleavitt
Contributor
krawlings
Contributor
I had the same problem as you are haveing now . I didn't realy see a beg change till after my 50th to 60th dives My SAC went from .8 to .9 's to know I am at 4.85 to 5.6 range The bigest thing that I did was work on my kick cycle(kick glide kick glide )and use more kick action from my knees . less muscles mass to have to feed oxygen to . and worked on my buoyancy. and I think allso a big help was I was a lot more relaxed in the water . good luck and give it some time it will come around .
I'm guessing you meant to say you can lose 200 PSI from tank cooling pretty easily. Losing 200 bar from tank cooling would require some scorching hot tanks. Like melting metal hot.
20 bar is possible at the extreme end with a tank thats 50c having been in the sun in a pickup and getting into cold water.
200 bar would require taking it from a fire and placing it into liquid nitrogen
Yes. This is worth repeating. Dive more, and you'll get better. Whether you admit it or not, there is an amount of comfort that you may or may not have as a novice. After you do another 50 dives... Then you'll be like, "Wow, I can't believe I used to breathe so much gas..."
Better gas consumption isn't a trick, or skip breathing, it just comes with more comfort and experience in the water. (of course there are times when even experienced divers use a lot of gas, but that is usually in a working or maybe a vigorous swimming environment)
Buoyant1
Contributor
The first thing I did was get a larger cylinder, (steel 119) ONLY to put me on a level playing field with the guys I was diving with who were diving al80's...when I did that, I stopped worrying about my gas consumption, and settled down. Worked great!!!
Now I'm on a level playing field with the guys I dive with who all have the same size cylinders (except for the guys that are using doubles) and when I dive an 80, my gas consumption is fine! I had one of my 119's on a recent trip to Florida, and ended up using the same tank for both dives, and came up with 700psi (52 and 46 minutes respectively in 26fsw)...THAT was cool!
Now I'm on a level playing field with the guys I dive with who all have the same size cylinders (except for the guys that are using doubles) and when I dive an 80, my gas consumption is fine! I had one of my 119's on a recent trip to Florida, and ended up using the same tank for both dives, and came up with 700psi (52 and 46 minutes respectively in 26fsw)...THAT was cool!
asj
Registered
I'm guessing you meant to say you can lose 200 PSI from tank cooling pretty easily. Losing 200 bar from tank cooling would require some scorching hot tanks. Like melting metal hot.
I meant 20 bar, but 200 psi is close enough. ooops. :inquisition:
OP I'm sure meant 20 bar too, since I'm assuming he's using ~230 bar tanks, that would mean he vents the entire tank in a few minutes...
I've seen 20 bar, just filled on the boat and off the side, 210 bar becomes 190 bar pretty easily.
You can decrease your SAC as much as 15-20% just by putting your hands together while you drive. Stop waving at the fishes and get your buoyancy down pat. Stopping your sculling will allow you to do just that and also to assume a more horizontal position.
I hope this helps.
I hope this helps.
First off, as everyone has said, high gas consumption is typical for a novice diver, and it will improve as you become more comfortable with the mechanics of diving.
But what actually CHANGES as people get more experience, that explains why they use less gas? I would offer that it is two things -- they become more relaxed (and therefore breathe more effectively) and they become more efficient (so they don't work as hard).
The body's primary drive to breathe is the CO2 level in the blood. This is directly related to the volume of air that is driven through the air cells in the lungs per unit time. You would think, then, that the faster you breathed, the lower your CO2 would drop -- and to an extent, that's true. But the problem is that the top of the airways, the trachea (or windpipe) and the large bronchi, don't exchange any gas. So all the air that ventilates THEM is essentially wasted, from a CO2 point of view. And if you breathe rapidly and shallowly, that's ALL you ventilate -- the air never gets past the big channels and into the small air sacs where gas is exchanged. New divers, because of anxiety sometimes and because they're unused to the feeling of breathing from a regulator, tend to use a very rapid, shallow breathing pattern. This blows through a lot of gas very quickly, and doesn't drop CO2 effectively. This can lead to anxiety, a feeling of not being able to breathe, or post-dive headaches.
The solution is a slow, rhythmic pattern of inhalation and exhalation, with a very brief pause at the end of each swing. Some people read this as meaning you should inhale everything you possibly can, and exhale everything you possibly can, but that's not the point. If you do that, you'll have significant buoyancy changes! What you want is a slightly larger breath than what you would take sitting on your couch, more like what you would do if you were doing yoga or meditating, and a steady, slow rate of both inhalation and exhalation.
But one of the biggest things that will ALLOW you to have a smooth, rhythmic breathing pattern is relaxation. And to be relaxed, you have to be stable. Being stable has several components. The first is weighting yourself correctly. This is important because being light means you have to swim to stay down, which is uncomfortable and uses a lot of energy. Being heavy might seem attractive, but a large air bubble in your BC will cause a great deal of buoyancy shift as you go up and down, and can lead to constant venting and adding, as well as a lot of swimming, all of which uses air. Correct weighting makes it easiest to achieve and retain neutral buoyancy, and lower your workload and your tension.
Once you have gotten your weighting right, the next trick is to distribute it effectively. In warm water, that usually isn't very hard, because you usually aren't carrying much weight. In cold water, it's a different story. New divers, especially in dry suits, may be carrying up to 30 pounds (or more) of lead. If they put it all in weight integrated pockets or weight belts around their waists, it's likely they'll end up out of balance. In this case, the minute they stop kicking, they rotate feet down, and they probably swim at a 30 degree or greater angle away from horizontal. In this scenario, you have two problems. One is that you are presenting a big frontal surface to the water, with a lot of resistance you have to overcome to move forward. The second is that, because your feet are pointing down, every kick pushes you up. If nothing countered that force, you'd just keep ascending. So, to stay where you are, you have to vent gas from your BC and remain continuously negative. That means, a good part of the energy that goes into every kick has . . . no net effect at all! It's just effort wasted, and gas used as a consequence.
So, shifting your weight around until you can float easily in a horizontal position means that you can aim your kick directly behind you, and all the force goes to push you forward, which is what you want.
Now, there is another component to stability, which is learning to function well as a tank/BC/person unit. I rarely see anyone talk about this, but you DO have to learn how to balance yourself and your equipment in the water. This is easier if your BC fits you well, and holds your tank firmly in the middle of your back. But it's still like learning to be the bicycle, and balance the rider. Until you get the hang of it, you're likely to feel as though you need to do a lot of waving your arms around to keep upright, and that's all wasted energy, too. THIS is one of the big components that just improves with practice (and with getting your own gear, too, if you get the right stuff).
Although streamlining gear DOES reduce effort, in the context of the inefficiencies of a new diver, a hanging strap or hose is insignificant compared with the other things I've already mentioned.
But the last piece is to learn to do less. Diving is a sport of gentle touring (unless you are spearfishing). Once you are stable, you don't have to kick to keep your balance, so don't! Go slow. Look for camouflaged creatures. Watch behavior, that you won't see if you blast past it. Diving a reef is like touring a museum -- if you march through, you won't see much!
Relaxation and efficiency . . . both come with time, but you can shorten the course by taking some thoughtful steps to change your gear and your procedures.
But what actually CHANGES as people get more experience, that explains why they use less gas? I would offer that it is two things -- they become more relaxed (and therefore breathe more effectively) and they become more efficient (so they don't work as hard).
The body's primary drive to breathe is the CO2 level in the blood. This is directly related to the volume of air that is driven through the air cells in the lungs per unit time. You would think, then, that the faster you breathed, the lower your CO2 would drop -- and to an extent, that's true. But the problem is that the top of the airways, the trachea (or windpipe) and the large bronchi, don't exchange any gas. So all the air that ventilates THEM is essentially wasted, from a CO2 point of view. And if you breathe rapidly and shallowly, that's ALL you ventilate -- the air never gets past the big channels and into the small air sacs where gas is exchanged. New divers, because of anxiety sometimes and because they're unused to the feeling of breathing from a regulator, tend to use a very rapid, shallow breathing pattern. This blows through a lot of gas very quickly, and doesn't drop CO2 effectively. This can lead to anxiety, a feeling of not being able to breathe, or post-dive headaches.
The solution is a slow, rhythmic pattern of inhalation and exhalation, with a very brief pause at the end of each swing. Some people read this as meaning you should inhale everything you possibly can, and exhale everything you possibly can, but that's not the point. If you do that, you'll have significant buoyancy changes! What you want is a slightly larger breath than what you would take sitting on your couch, more like what you would do if you were doing yoga or meditating, and a steady, slow rate of both inhalation and exhalation.
But one of the biggest things that will ALLOW you to have a smooth, rhythmic breathing pattern is relaxation. And to be relaxed, you have to be stable. Being stable has several components. The first is weighting yourself correctly. This is important because being light means you have to swim to stay down, which is uncomfortable and uses a lot of energy. Being heavy might seem attractive, but a large air bubble in your BC will cause a great deal of buoyancy shift as you go up and down, and can lead to constant venting and adding, as well as a lot of swimming, all of which uses air. Correct weighting makes it easiest to achieve and retain neutral buoyancy, and lower your workload and your tension.
Once you have gotten your weighting right, the next trick is to distribute it effectively. In warm water, that usually isn't very hard, because you usually aren't carrying much weight. In cold water, it's a different story. New divers, especially in dry suits, may be carrying up to 30 pounds (or more) of lead. If they put it all in weight integrated pockets or weight belts around their waists, it's likely they'll end up out of balance. In this case, the minute they stop kicking, they rotate feet down, and they probably swim at a 30 degree or greater angle away from horizontal. In this scenario, you have two problems. One is that you are presenting a big frontal surface to the water, with a lot of resistance you have to overcome to move forward. The second is that, because your feet are pointing down, every kick pushes you up. If nothing countered that force, you'd just keep ascending. So, to stay where you are, you have to vent gas from your BC and remain continuously negative. That means, a good part of the energy that goes into every kick has . . . no net effect at all! It's just effort wasted, and gas used as a consequence.
So, shifting your weight around until you can float easily in a horizontal position means that you can aim your kick directly behind you, and all the force goes to push you forward, which is what you want.
Now, there is another component to stability, which is learning to function well as a tank/BC/person unit. I rarely see anyone talk about this, but you DO have to learn how to balance yourself and your equipment in the water. This is easier if your BC fits you well, and holds your tank firmly in the middle of your back. But it's still like learning to be the bicycle, and balance the rider. Until you get the hang of it, you're likely to feel as though you need to do a lot of waving your arms around to keep upright, and that's all wasted energy, too. THIS is one of the big components that just improves with practice (and with getting your own gear, too, if you get the right stuff).
Although streamlining gear DOES reduce effort, in the context of the inefficiencies of a new diver, a hanging strap or hose is insignificant compared with the other things I've already mentioned.
But the last piece is to learn to do less. Diving is a sport of gentle touring (unless you are spearfishing). Once you are stable, you don't have to kick to keep your balance, so don't! Go slow. Look for camouflaged creatures. Watch behavior, that you won't see if you blast past it. Diving a reef is like touring a museum -- if you march through, you won't see much!
Relaxation and efficiency . . . both come with time, but you can shorten the course by taking some thoughtful steps to change your gear and your procedures.
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