I did all the stuff DBailey said and I've improved my sac rate 3 fold in my 80 dives. I also find it's hugely beneficial to start mentally preparing for a dive a few days before by going through my gear with a check list (ask your buddy to do the same), plan the dive early, visualize what you will do the morning of the dive and the dive itself. Eat a good breakfast and most importantly have FUN!
Running low on air quickly - need help and guidance
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John_B
Grasshopper
You aren't "running low on air quickly" you are "using up your air quickly".
Kill the motor. Quiet hands and quiet feet will make the most immediate difference. I'd bet you are finning without even realizing it, and probably sculling with your hands as well. Literally cross your arms and your fin tips, if you begin to sink, you haven't found your neutrally buoyancy. That's the starting place. Whenever you change depth, check again, and adjust with your inflator. Rinse and repeat. You'll eventually develop a feel for it.
Then slow down. Kick, glide, even hover. I'd bet you could kick half as hard and it would still be too much. It's not a race.
Finally, watch how little motion experienced divers make, then emulate that. My favorite diver (and best dive buddy) does entire dives with her arms crossed and just the slightest of fin kicks. She uses so little air, it's like she has gills. That's your target: running at idle, not redlined. Relax, the hustle and bustle of the busy world will still be there when you surface, there's no reason to bring it with you when you are diving.
Kill the motor. Quiet hands and quiet feet will make the most immediate difference. I'd bet you are finning without even realizing it, and probably sculling with your hands as well. Literally cross your arms and your fin tips, if you begin to sink, you haven't found your neutrally buoyancy. That's the starting place. Whenever you change depth, check again, and adjust with your inflator. Rinse and repeat. You'll eventually develop a feel for it.
Then slow down. Kick, glide, even hover. I'd bet you could kick half as hard and it would still be too much. It's not a race.
Finally, watch how little motion experienced divers make, then emulate that. My favorite diver (and best dive buddy) does entire dives with her arms crossed and just the slightest of fin kicks. She uses so little air, it's like she has gills. That's your target: running at idle, not redlined. Relax, the hustle and bustle of the busy world will still be there when you surface, there's no reason to bring it with you when you are diving.
I write about this periodically, but I haven't for a while, so . . .
The minimum amount of volume you have to move through the gas exchange part of your lungs is determined by your production of carbon dioxide. There is no way around that; you have to breathe what you have to breathe, to keep the CO2 level in your blood normal. Muscle activity causes increased CO2 production, so for the diver who wants to maximize his time underwater, becoming efficient and moving slowly is key, and I will talk about things that impact that a little later.
But it's important to note that I said that what we are talking about is the air that moves through the GAS EXCHANGE part of the lungs. Your lungs resemble upside-down trees -- as the air enters them, it moves through the trachea (trunk) into the major bronchi (primary branches) and then out through smaller bronchi until it reaches the air sacs, or alveoli, which are analogous to leaves. It is really only in the "leaves" that gas exchange takes place -- all the air that is sitting in the branches is not participating in the removal of CO2. As you exhale, you fill the branches with CO2-rich air, and when you inhale, you take that gas back into the alveoli. That volume, stuck in the branches, is called "dead space", and there is nothing you can do to diminish it (although you can increase it by adding a snorkel to the picture!).
So, let's say you are going to move 5l of air through your lungs in a minute. If you do it with 5 1l breaths, the dead space will be a small proportion of the volume of each breath, and most of the air will go to the air sacs. If you do it through 20 1/4l breaths, most of the gas is going to oscillate back and forth in the dead space, and very little CO2 elimination will take place. Anxiety tends to cause a rapid, shallow breathing pattern, which is not only very inefficient for CO2 reduction, but, because it allows CO2 to rise, causes additional anxiety! This is the root of the advice to use a slow, deep breathing pattern on Scuba, although too deep can cause buoyancy issues. If you did the "fin pivot" exercise in your OW class, you were looking for the breathing pattern that had you begin to exhale just as your body began to rise, and begin to inhale just as it began to fall, which is about the most efficient pattern you can use.
Now, assuming that you have conquered the anxious panting, the next thing to look at is minimizing exertion. The fastest place to address that is to SLOW DOWN. Most new divers swim constantly. In part, this is due to instability in the water -- if they stop, they pitch head or feet down, or roll on their sides. Swimming is like moving a bicycle, because it gives you stability. But much marine life survives by camouflage, so you see much less if you are zooming . . . and you have less time to see it in, too.
So, if people swim because they are unstable, how do you develop stability? It starts with weighting. Carrying the correct amount of weight is important, because being significantly overweighted causes buoyancy instability, and the diver who is constantly adjusting his BC, and swimming up or down to correct deviations from depth, is using more gas. But what is also important is having that weight in just the right places, because physics is inexorable. If you don't have the things that sink balanced over things that rise, and you do not do anything to counter the forces (eg. swim), you will rotate until those pieces have lined themselves up. For new cold water divers using integrated weight BCs, that will often mean rotating into a significantly feet-down position. Occasionally, especially if using aluminum tanks, it will result in feet up.
A diver who is not horizontal, and who is kicking, will of necessity be propelling himself to a different depth. If his feet are below him, he's swimming up; if they are above him, he's swimming down. Now, assuming he wants to stay where he is, there is only one solution . . . he has to adjust his buoyancy to counter the force he's creating with his fins. If he's swimming up, he has to remain negative in order not to rise. And of course, when he attempts to stop, he will SINK, which immediately results in more kicking. This vicious cycle uses gas very fast, and is the primary cause of increased gas use in novice divers who have made it past the anxious panting stage and who aren't incorrigible zoomers.
So, time spent determining the actual required weighting, and balancing your equipment so that you can hover in a horizontal position WITHOUT kicking, is key in reducing gas consumption. Pair those with relaxed breathing and a slow pace, and you'll see your bottom time increase enormously.
However, as a final note -- CO2 production is proportional to body mass. Bigger people need to move more volume through their lungs than smaller people, and people with more muscle mass will use more than people with a higher body fat proportion (because fat has a low metabolic quotient). So if you are significantly bigger than your buddy (as many men who dive with their wives are, for example) it's unlikely you will ever match consumption. If you want to match bottom time, you will need a bigger tank.
The minimum amount of volume you have to move through the gas exchange part of your lungs is determined by your production of carbon dioxide. There is no way around that; you have to breathe what you have to breathe, to keep the CO2 level in your blood normal. Muscle activity causes increased CO2 production, so for the diver who wants to maximize his time underwater, becoming efficient and moving slowly is key, and I will talk about things that impact that a little later.
But it's important to note that I said that what we are talking about is the air that moves through the GAS EXCHANGE part of the lungs. Your lungs resemble upside-down trees -- as the air enters them, it moves through the trachea (trunk) into the major bronchi (primary branches) and then out through smaller bronchi until it reaches the air sacs, or alveoli, which are analogous to leaves. It is really only in the "leaves" that gas exchange takes place -- all the air that is sitting in the branches is not participating in the removal of CO2. As you exhale, you fill the branches with CO2-rich air, and when you inhale, you take that gas back into the alveoli. That volume, stuck in the branches, is called "dead space", and there is nothing you can do to diminish it (although you can increase it by adding a snorkel to the picture!).
So, let's say you are going to move 5l of air through your lungs in a minute. If you do it with 5 1l breaths, the dead space will be a small proportion of the volume of each breath, and most of the air will go to the air sacs. If you do it through 20 1/4l breaths, most of the gas is going to oscillate back and forth in the dead space, and very little CO2 elimination will take place. Anxiety tends to cause a rapid, shallow breathing pattern, which is not only very inefficient for CO2 reduction, but, because it allows CO2 to rise, causes additional anxiety! This is the root of the advice to use a slow, deep breathing pattern on Scuba, although too deep can cause buoyancy issues. If you did the "fin pivot" exercise in your OW class, you were looking for the breathing pattern that had you begin to exhale just as your body began to rise, and begin to inhale just as it began to fall, which is about the most efficient pattern you can use.
Now, assuming that you have conquered the anxious panting, the next thing to look at is minimizing exertion. The fastest place to address that is to SLOW DOWN. Most new divers swim constantly. In part, this is due to instability in the water -- if they stop, they pitch head or feet down, or roll on their sides. Swimming is like moving a bicycle, because it gives you stability. But much marine life survives by camouflage, so you see much less if you are zooming . . . and you have less time to see it in, too.
So, if people swim because they are unstable, how do you develop stability? It starts with weighting. Carrying the correct amount of weight is important, because being significantly overweighted causes buoyancy instability, and the diver who is constantly adjusting his BC, and swimming up or down to correct deviations from depth, is using more gas. But what is also important is having that weight in just the right places, because physics is inexorable. If you don't have the things that sink balanced over things that rise, and you do not do anything to counter the forces (eg. swim), you will rotate until those pieces have lined themselves up. For new cold water divers using integrated weight BCs, that will often mean rotating into a significantly feet-down position. Occasionally, especially if using aluminum tanks, it will result in feet up.
A diver who is not horizontal, and who is kicking, will of necessity be propelling himself to a different depth. If his feet are below him, he's swimming up; if they are above him, he's swimming down. Now, assuming he wants to stay where he is, there is only one solution . . . he has to adjust his buoyancy to counter the force he's creating with his fins. If he's swimming up, he has to remain negative in order not to rise. And of course, when he attempts to stop, he will SINK, which immediately results in more kicking. This vicious cycle uses gas very fast, and is the primary cause of increased gas use in novice divers who have made it past the anxious panting stage and who aren't incorrigible zoomers.
So, time spent determining the actual required weighting, and balancing your equipment so that you can hover in a horizontal position WITHOUT kicking, is key in reducing gas consumption. Pair those with relaxed breathing and a slow pace, and you'll see your bottom time increase enormously.
However, as a final note -- CO2 production is proportional to body mass. Bigger people need to move more volume through their lungs than smaller people, and people with more muscle mass will use more than people with a higher body fat proportion (because fat has a low metabolic quotient). So if you are significantly bigger than your buddy (as many men who dive with their wives are, for example) it's unlikely you will ever match consumption. If you want to match bottom time, you will need a bigger tank.
Here's an exerpt on the subject from our first book, The Scuba Snobs' Guide to Diving Etiquette:
Not everyone uses up their air at the same rate. We get that. But some people are terrible and dont need to be. Some air suckage is correctable. You can, through good diving practices, reduce your air consumption. Here are some tips for you air suckers to improve your bottom time:
a) Check your weighting. If you go through air faster than everyone else, there is a real good chance you are over-weighted or under-weighted.
b) Trim your buoyancy often. We regularly observe other divers and see that they cannot hover. To remain at a certain depth, they are kicking or moving their arms to maintain that depth. Those movements burn air. Use your low pressure inflater/ deflater- that is what it is there for. Maintain neutral buoyancy and you will use a lot less air.
c) Move less. Swim less. Stop and smell the coral. Look for pretty little things under ledges. Dont be in constant motion.
d) Stay a few meters above the rest of the group.
If you will do these four things, we are confident that you will suck less air, and for some of you, a lot less air.
And of course, the more you dive the more comfortable and relaxed you will be in the water, and your air consumption rate will improve.
DivemasterDennis
This was an adventurous, high stress hammerhead shark dive, 90 feet deep, strong currents, with special entry and exit rules because there was no mooring and the boat was at the mercy of ten foot high waves. In addition to all of that, we had an hour long boat ride to get the site, and it was a very rough ride. Dennis puked more than once. On arrival at the dive site we were all anxious to make the dive. Most of us listened to the briefing about current, depth, where to look for the hammerheads, and so on. Most of us. But one diver, the lady, was clueless. About 14 minutes into the dive, just when we first sighted a nice school of hammerheads, the lady signaled low on air. Actually she was way beyond low, and because of conditions, the dive came to an end for everyone. After fourteen minutes, and she was down to about 400 psi in her tank. Everyone else had at least four times that much. The lady was the buzz killer. She cheated the rest of us out of our dive. Why do we say it was her fault? Because it was! She swam around like a crazy person the entire time; she didnt listen to the briefing and so hung in the strongest part of the current; she had negligible buoyancy control; she was clearly overweighted (and overweight); she was not qualified to do the dive and so was anxious the entire time. She also didnt monitor her gauges or she would have known that for most of the dive she was ten feet or more deeper than the profile planned, and she never corrected for that. Its a miracle she looked at her gauges before her air was totally depleted!
The lady was not allowed to do the second dive. She should never have been on the first dive. She misrepresented her experience and competence. While she was joking about getting a t-shirt that said I survived the Molokai Shark Dive, everyone else on the boat was wishing she hadnt. No one has to be an air sucker. We can all do a little better. Come on people, work on your skills!
DONT FEED ANYTHING TO ANYTHING THAT LIVES IN THE OCEAN
We feel very strongly about this. The only real exception is if you puke in the ocean because that is really a part of the ecosystem. We dont go on shark dives where the
Not everyone uses up their air at the same rate. We get that. But some people are terrible and dont need to be. Some air suckage is correctable. You can, through good diving practices, reduce your air consumption. Here are some tips for you air suckers to improve your bottom time:
a) Check your weighting. If you go through air faster than everyone else, there is a real good chance you are over-weighted or under-weighted.
b) Trim your buoyancy often. We regularly observe other divers and see that they cannot hover. To remain at a certain depth, they are kicking or moving their arms to maintain that depth. Those movements burn air. Use your low pressure inflater/ deflater- that is what it is there for. Maintain neutral buoyancy and you will use a lot less air.
c) Move less. Swim less. Stop and smell the coral. Look for pretty little things under ledges. Dont be in constant motion.
d) Stay a few meters above the rest of the group.
If you will do these four things, we are confident that you will suck less air, and for some of you, a lot less air.
And of course, the more you dive the more comfortable and relaxed you will be in the water, and your air consumption rate will improve.
DivemasterDennis
This was an adventurous, high stress hammerhead shark dive, 90 feet deep, strong currents, with special entry and exit rules because there was no mooring and the boat was at the mercy of ten foot high waves. In addition to all of that, we had an hour long boat ride to get the site, and it was a very rough ride. Dennis puked more than once. On arrival at the dive site we were all anxious to make the dive. Most of us listened to the briefing about current, depth, where to look for the hammerheads, and so on. Most of us. But one diver, the lady, was clueless. About 14 minutes into the dive, just when we first sighted a nice school of hammerheads, the lady signaled low on air. Actually she was way beyond low, and because of conditions, the dive came to an end for everyone. After fourteen minutes, and she was down to about 400 psi in her tank. Everyone else had at least four times that much. The lady was the buzz killer. She cheated the rest of us out of our dive. Why do we say it was her fault? Because it was! She swam around like a crazy person the entire time; she didnt listen to the briefing and so hung in the strongest part of the current; she had negligible buoyancy control; she was clearly overweighted (and overweight); she was not qualified to do the dive and so was anxious the entire time. She also didnt monitor her gauges or she would have known that for most of the dive she was ten feet or more deeper than the profile planned, and she never corrected for that. Its a miracle she looked at her gauges before her air was totally depleted!
The lady was not allowed to do the second dive. She should never have been on the first dive. She misrepresented her experience and competence. While she was joking about getting a t-shirt that said I survived the Molokai Shark Dive, everyone else on the boat was wishing she hadnt. No one has to be an air sucker. We can all do a little better. Come on people, work on your skills!
DONT FEED ANYTHING TO ANYTHING THAT LIVES IN THE OCEAN
We feel very strongly about this. The only real exception is if you puke in the ocean because that is really a part of the ecosystem. We dont go on shark dives where the
LowDrag
Contributor
Teflon-Don...the first thing I notice is a bit of anxiety over going through your air quicker. You gotta put that behind you. It doesn't matter what your air consumption rate is in the beginning, most of the people you dive are in the same boat anyway. The previous posts have all been info that I have listened to in the past. I have worked on not sculling, getting my trim in check and getting my buoyancy straightened out. Don't let me mislead you on these subject's, I am still working on all them every time I dive. I also went to a better set of reg's which is something you have not mentioned. I started with a less expensive ScubaPro first and second stage and then later came across a deal for a pair of Mk25/S600's that I could not pass up. I noticed after the first dive that my SAC rate had improved, that was when I was putting my info into my log book. My SAC dropped pretty decently. I am not trying to get you to buy anything just giving you an example is all. Combine time, dives and comfortableness and you will get your SAC where you want it.
Good luck
Good luck
The Kraken
He Who Glows in the Dark Waters (ADVISOR)
ScubaBoard Supporter
Scuba Instructor
Divemaster
I like the way JohnB put it. Sage advice.
And you can never go wrong with TSandM's advice.
Safe dives . . . . . .
. . . safer ascents !
the K
And you can never go wrong with TSandM's advice.
Safe dives . . . . . .
. . . safer ascents !
the K
Yoga helped me out a gret deal when I first started diving. It taught me breath control and relaxation techniques.
OP
Teflon-Don
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Wow this certainly is a helpful community we got over here, I really appreciate you taking the time to give me your words of wisdom.
Just so you have a better angle of where I'm coming from, I'll explain a little about myself and the group that I took the OW classes with. I know them all pretty well, some better than others, we are a group of 4. Sometime during the OW classes a couple of newcomers joined us on certain dives, not including the 2 instructors at all times. The other guys, although no picture of great health, have grown up around the sea and were into free diving several years before they considered scuba. They vary in size and weight, all of us are smokers (I've cut down drastically now), we were all new to Scuba. Ive always loved the sea and felt comfortable there (although once had a near death experience and nearly drowned when I was much younger) but never considered diving, because:
a) I've moved around a lot in my life and wasn't living close to the sea (now I do).
b) I didn't have the available funds to really get in to it.
c) I thought that it would probably be something that I was unable to achieve.
About a year ago I decided to change the old (bad) direction my life was taking me and turn a new leaf, in ALL aspects. I've always loved the idea of Scuba (and extreme sports) and generally being one with nature. So without straying away from the subject matter too much, a year ago I was at a tropical resort on holiday and planned to take PADIs 'Introduction to Scuba', filled out all the necessary paperwork and started (I think it was about a 3 hour course then 1 supervised dive). The instructor only had me and 1 other guy in the class (who'd apparently done scuba before but didn't have a certificate). Anyway the instructor is explaining away to us and the more he talks the more I'm thinking "damn this is a lot of vital information to take in" (they give you no reading material), plus we are sitting in the lobby of the aqua-fanatics training center which was basically sofas and chairs on sand, with a bunch of lockers surrounding us, nice looking but not the most serious environment you'd expect. Before you know it they take you to the shore at about 3 meters depth to start the first skills. Right off the bat I was feeling uncomfortable and having issues with my reg and breathing, and was starting to hyperventilate, kept on asking the instructor "are you sure there's nothing wrong with the reg because it doesn't feel right". He was just saying "relax this is a common issue with beginner divers just be at ease breath slow deep breaths". I listened to his advice but as soon as he started showing us the first skill of clearing your mask halfway, I was thinking "hell no"!
I can't get the hang of breathing right now and it's just going to get worse by filling my mask with water. I ascended (for about the 4th time) and told the instructor, I'm sorry about this but I can't continue, I'm not usually one to quit on things but I dont want to waste your time any more or the other guys, "I just dont feel comfortable". He told me not worry about it, just to relax and swim around him from above and when I was ready, just come back down. I said sorry but its just not going to happen, as I reached the shore and walking back to the training center with my tail between my legs in complete embarrassment over what just happened, he pops back up, and calls for me I turn around he says "Don't ever give up on your dream of being a scuba diver, I know you can do it!" (sounds like a scene from a movie I know, but this really happened). Then he submerged himself in the water, never to be seen again.
From that day on, the instructors words kept playing in my mind, I never really had the intention to give up completely but jumped on the opportunity when myself and the 3 guys (the OW guys), decided to start taking the OW class about 3 months ago. After reading all the material, doing the knowledge test and pool practicals etc.. I was in much better shape and felt much more at ease, never feeling as uncomfortable as I did on that first day.
The more you guys write about what is important for me to lower my air consumption the more it is obvious to me that I need to take all the advice and put it in to practice. The difference between how I am now and that dreaded first day is like night and day, but there is still a long (fun) journey ahead of me and many improvements to make. I will keep you posted on my progress, thank you all again for your help.
P.S The reason I haven't mentioned my equipment is because I don't own any as of yet, I'm still renting the equipment from the scuba shop. I want to get in a little more experience before I consider buying any gear so I know what's right for me, and not make any hasty bad decisions.
Just so you have a better angle of where I'm coming from, I'll explain a little about myself and the group that I took the OW classes with. I know them all pretty well, some better than others, we are a group of 4. Sometime during the OW classes a couple of newcomers joined us on certain dives, not including the 2 instructors at all times. The other guys, although no picture of great health, have grown up around the sea and were into free diving several years before they considered scuba. They vary in size and weight, all of us are smokers (I've cut down drastically now), we were all new to Scuba. Ive always loved the sea and felt comfortable there (although once had a near death experience and nearly drowned when I was much younger) but never considered diving, because:
a) I've moved around a lot in my life and wasn't living close to the sea (now I do).
b) I didn't have the available funds to really get in to it.
c) I thought that it would probably be something that I was unable to achieve.
About a year ago I decided to change the old (bad) direction my life was taking me and turn a new leaf, in ALL aspects. I've always loved the idea of Scuba (and extreme sports) and generally being one with nature. So without straying away from the subject matter too much, a year ago I was at a tropical resort on holiday and planned to take PADIs 'Introduction to Scuba', filled out all the necessary paperwork and started (I think it was about a 3 hour course then 1 supervised dive). The instructor only had me and 1 other guy in the class (who'd apparently done scuba before but didn't have a certificate). Anyway the instructor is explaining away to us and the more he talks the more I'm thinking "damn this is a lot of vital information to take in" (they give you no reading material), plus we are sitting in the lobby of the aqua-fanatics training center which was basically sofas and chairs on sand, with a bunch of lockers surrounding us, nice looking but not the most serious environment you'd expect. Before you know it they take you to the shore at about 3 meters depth to start the first skills. Right off the bat I was feeling uncomfortable and having issues with my reg and breathing, and was starting to hyperventilate, kept on asking the instructor "are you sure there's nothing wrong with the reg because it doesn't feel right". He was just saying "relax this is a common issue with beginner divers just be at ease breath slow deep breaths". I listened to his advice but as soon as he started showing us the first skill of clearing your mask halfway, I was thinking "hell no"!
I can't get the hang of breathing right now and it's just going to get worse by filling my mask with water. I ascended (for about the 4th time) and told the instructor, I'm sorry about this but I can't continue, I'm not usually one to quit on things but I dont want to waste your time any more or the other guys, "I just dont feel comfortable". He told me not worry about it, just to relax and swim around him from above and when I was ready, just come back down. I said sorry but its just not going to happen, as I reached the shore and walking back to the training center with my tail between my legs in complete embarrassment over what just happened, he pops back up, and calls for me I turn around he says "Don't ever give up on your dream of being a scuba diver, I know you can do it!" (sounds like a scene from a movie I know, but this really happened). Then he submerged himself in the water, never to be seen again.
From that day on, the instructors words kept playing in my mind, I never really had the intention to give up completely but jumped on the opportunity when myself and the 3 guys (the OW guys), decided to start taking the OW class about 3 months ago. After reading all the material, doing the knowledge test and pool practicals etc.. I was in much better shape and felt much more at ease, never feeling as uncomfortable as I did on that first day.
The more you guys write about what is important for me to lower my air consumption the more it is obvious to me that I need to take all the advice and put it in to practice. The difference between how I am now and that dreaded first day is like night and day, but there is still a long (fun) journey ahead of me and many improvements to make. I will keep you posted on my progress, thank you all again for your help.
P.S The reason I haven't mentioned my equipment is because I don't own any as of yet, I'm still renting the equipment from the scuba shop. I want to get in a little more experience before I consider buying any gear so I know what's right for me, and not make any hasty bad decisions.
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industrious95
Contributor
I was a major air hog when I started. Experience is a great teacher.
Breath slowly and calmly. Obviously, if you're finning or moving, you're going to breathe more, but you'll learn over time that you don't have to gulp the tank down, it's not going to disappear if you breathe too slowly.
I've been doing a very light workout on the treadmill for the past 10 years and I think it's made me more efficient. Losing weight also helped. But don't measure yourself against other divers, that will only frustrate you. Maybe find a dive buddy who breathes at a similar rate so you won't be apprehensive about making him cut his dive short. At least, I know that was one of my issues when I started out.
When I'm diving with strangers and need to buddy up with an unknown, one of the questions I ask is "how long do you think your tank's going to last at this depth?" I'm not saying I always find a match, but it's a lot better than looking at my gauge and seeing 500 PSI while his has 1500. Or visa-versa.
Breath slowly and calmly. Obviously, if you're finning or moving, you're going to breathe more, but you'll learn over time that you don't have to gulp the tank down, it's not going to disappear if you breathe too slowly.
I've been doing a very light workout on the treadmill for the past 10 years and I think it's made me more efficient. Losing weight also helped. But don't measure yourself against other divers, that will only frustrate you. Maybe find a dive buddy who breathes at a similar rate so you won't be apprehensive about making him cut his dive short. At least, I know that was one of my issues when I started out.
When I'm diving with strangers and need to buddy up with an unknown, one of the questions I ask is "how long do you think your tank's going to last at this depth?" I'm not saying I always find a match, but it's a lot better than looking at my gauge and seeing 500 PSI while his has 1500. Or visa-versa.
The way I see it...
There is a certain limited cf of air in your tank. With each breath, you use a portion of this air. That's your tidal volume. I believe the average is around 500 ml or about 7ml/kg. If you are a manly man you are physiologically wired to take a larger breath then a petite female. Hence an automatic hit for most of you guys when it comes to gas consumption. But lets say you are average and each breath consumes 500 ml from your tank. All else equal, it's obvious then that the more breaths you take, the faster the tank will empty. Now what would make you breathe faster and harder? Physical stress is one reason, such as swimming, arm movement, fighting trim...I think you get the idea. I think TSandM covered the reason for this very well. Its the same thing on land, you exercise, you breathe harder. That's why you read so many recommendations to get neutrally buoyant and in trim and to avoid excess movements.
So what else? Emotional stress, such as excitement, anxiety or dealing with the unexpected. That's one reason that even experienced divers know their sac rate may rise if there is an unexperienced event and will often take this into account when gas planning. And new divers are excited divers, or at least they should be! That's why many of us recommend the slow, deep breaths such as yoga breaths. Not only does this maximize respiratory effort and reduce dead space but it also helps relax the diver. Its hard to get too stressed when your breathing is slow and relaxed. In fact, deep breathing is a relaxation technique in itself. I think controlled breathing, diaphragmatic breathing or relaxation breaths are an important aspect of scuba that is often overlooked or under appreciated.
Just my take.
There is a certain limited cf of air in your tank. With each breath, you use a portion of this air. That's your tidal volume. I believe the average is around 500 ml or about 7ml/kg. If you are a manly man you are physiologically wired to take a larger breath then a petite female. Hence an automatic hit for most of you guys when it comes to gas consumption. But lets say you are average and each breath consumes 500 ml from your tank. All else equal, it's obvious then that the more breaths you take, the faster the tank will empty. Now what would make you breathe faster and harder? Physical stress is one reason, such as swimming, arm movement, fighting trim...I think you get the idea. I think TSandM covered the reason for this very well. Its the same thing on land, you exercise, you breathe harder. That's why you read so many recommendations to get neutrally buoyant and in trim and to avoid excess movements.
So what else? Emotional stress, such as excitement, anxiety or dealing with the unexpected. That's one reason that even experienced divers know their sac rate may rise if there is an unexperienced event and will often take this into account when gas planning. And new divers are excited divers, or at least they should be! That's why many of us recommend the slow, deep breaths such as yoga breaths. Not only does this maximize respiratory effort and reduce dead space but it also helps relax the diver. Its hard to get too stressed when your breathing is slow and relaxed. In fact, deep breathing is a relaxation technique in itself. I think controlled breathing, diaphragmatic breathing or relaxation breaths are an important aspect of scuba that is often overlooked or under appreciated.
Just my take.
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