PDA

View Full Version : How to improve the air consumption



junzhang
08-30-2008, 08:03
I find I use much more air than my buddy (who's always a more experienced diver than me so far) and every dive is ended because I am low in air. I know the way to reduce air consumption is to relax, and improve your streamline in water..but somehow I still use bit more..

I hope I can get some advice about how to improve it here,some small tips, maybe I can try them on my next dive..cheers

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
08-30-2008, 09:19
Streamlining is 3rd order at slow speeds.- you should go slow! Streamline, of course, but don't get carried away. It's not the most important thing.

New divers just use more air. I think it really comes down to buyoancy control and psychology.

If you are not completely neutral you will use energy kicking in order to maintain the same depth. It might be so subtle that you are not aware of it. I dropped my consumption rate by 15% by concentrating on being completely neutral at all times- i.e. no finning allowed, except to move from place to place!

Also, if you are overweighted you will need to contantly fill and dump your BC to stay neutral as you change depth. This will waste a lot of air. One sign that you are overweighted is that your BC has a lot of water in it after a dive. By getting my weight belt right I dropped my consumption rate by 25%.

Most of the rest was/is psychological- right now you are probably very aware of your breathing. You want to get so used to diving that you are not aware of your breathing any longer. After 100+ dives, I am still not quite there, but I'm not working on improving it. And NOT working on it, helps in this case since my average consumption rate is contunuing to drop.

Keep diving!

No Misses
08-30-2008, 09:26
You hit on the top 2 things - Streamlining and Relaxing.

Streamlining: Are your really streamlined? There are multiple components to this.
-Are you carrying the proper ampunt of lead? If you are overballasted, you will have to put more air in your BC at depth. This will make you "wider" and adversly affect your streamlining.
-While diving, what do you do with your arms? could holding them straight along your body improve your profile?
-What danglies are hanging off of you? Cameras, lights, consoles, etc. creat drag when they are not tucked away.

Relaxing: This is one that only you can improve. Time in the water usually helps. More formal training may help you become a more comfortable diver.

Trim: Ask your dive buddy to critique your trim while swimming. If they can shoot video, it would be even better. Many divers swim head up or head down without being aware of it. If you can see video of your swimming, the flaws will jump out at you. When you stop finning, does your body rotate?

Proper bouyancy: Are you finning while your dive buddy is just hovering? Do you have to fin to hold your depth?

Depth: If you know that you use more gas than your buddy. Try staying 5-10 feet above them. The lower pressure will help you conserve gas.

Activity: Many divers jet around looking under every rock. This raises your SAC rate. Try to mosey around. Don't be in a hurry to get from point A to point B.

Good luck and keep diving.

rktman26
08-30-2008, 09:47
Another thing that helps as well is being physically fit. It takes some work to get in shape, if you're not already, but the benefits are worth it.

LCF
08-31-2008, 09:14
Relaxation and comfort definitely help gas consumption, and they only come with time. But the biggest reduction in gas need comes with becoming efficient underwater. The more muscle you have to use to dive, the more gas you will need -- there is no way around that!

So, how to become efficient? Begin with proper weighting. Doing a formal weight check is well worth while. You don't have to do it at the end of a dive. Weight yourself neutral at the surface with full tanks, and then add a pound for each 13 cubic feet of gas you intend to use (usually all but 500 psi is a good calculation).

Now, since you are diving in South Australia, I would assume you're diving cold water and need a fair amount of exposure protection, and therefore weight. Where you put the weight will affect your efficiency. If you have a lot of weight on a belt, or in weight pouches around the waist of your BC, you are likely to be obligated to assume a foot-down position in the water. The lift from your BC is in front of the weight you're carrying, so you rotate to raise the BC and lower your lower body. Then, any kicking you do drives you upward, so you have to stay negative to avoid climbing in the water column. Part of every kick is energy you're expending just to stay where you are! Moving weight around so that you are balanced will mean you can be still when you want, and the kicking you do will all propel you where you want to go. You can move weight up by moving the tank higher, using trim pockets (if your BC has them), putting an ankle weight around the tank neck, or using something like the XS Scuba weight pockets on your cambands.

Once you are balanced, the next key is not to rush around underwater. Much underwater life is camouflaged, and you'll miss a lot of it if you're racing past. Slowing down reduces gas usage, too!

One place where a lot of new divers waste energy is by swimming with their hands. The hands are not very effective for underwater propulsion, but they do use energy (and therefore gas). When you find yourself wanting to use your hands, try to figure out why you feel that way. Often, the desire to use the hands is a problem with buoyancy or balance. If it's just habit, swimming with your hands clasped for a while can help you break it.

And over all, be patient, and go diving. The more you do this, the better you get at it.

Splitlip
08-31-2008, 09:27
Proper breathing too. Inhale deeply. Pause (think of "h" sound not "k" sound. Keeps your air passage open).Exhale completely to expell CO2. Do it slowly and calmly. Not to be confused with skip breathing.

Also move deliberately and slowly. Don't waste energy pushing through the dense medium if there is no need.

Grin
09-01-2008, 08:23
It seems when we first dive we are excited and we want to get somewhere, so we paddle around at a rate that equals jogging on land. You will notice other divers hitting the water and racing down and away. They can't get there fast enough! You gotto break that mindset and enjoy. Sink down slow, and try to trim out about 20 ft off the bottom then liesurly swim at a speed that doesn't get your heart pounding, and you breathing like you just ran a mile. Your gas consumption will go way down, you will feel great throughout the day and at the end of the day, you reduce many diving related injury issues from DCS to clearing and ear problems etc... when you slow everything down.
Your problem is you dive buddy having to do the same thing as you. Hopefully you can get them to slow down for you. More than likely they will see the benefits as soon as they do it your way a few times. If they don't I say get a pony bottle and treat every dive as a solo dive and go your speed. Gotto look out for #1 and if they are not staying with you then your speeding up to feel safe is not a great idea. Either they comply easily and willingly or you adjust accordingly for #1(you).

Rileybri
09-01-2008, 08:39
Is it me or are we missing the big one tree for the forest here? How big or small are you compared to you buddy? Size does matter (:smiley2:).. If you are 225lbs and your buddy is a whopping 115lbs you can relax all you want and streamline all you want and you will still never have a better SAC rate than they will. Just basic physiology. A better measure of you Air consumption rate is to track you SAC rate from dive to dive and strive to get every dive just a bit better. This is a basic SAC rate Calculator (http://www.spearfishing.org/bruces_tips/java/sac.html) that was passed on to me from a ST member and I am now doing the same. Dont worry about who is calling the dives and for what. You got to come up some time right?? If after you have loogs enough dives to get your SAC down and you are still thumbing the dives and it is still getting to you (air hog!) than look into getting an bigger tank. More gas=more time! good luck and remember this is a great excuse to get out and dive more!

Skred
09-01-2008, 09:54
While not as high on the list as the other great points already listed, I would add that it is important that the gear you are using fit correctly. A wetsuit that doesn't fit right around your trunk could cause you to use more gas at depth as the suit compresses and makes it harder to feel like you've taken a full breath.

junzhang
09-02-2008, 19:05
Thanks for all your advices. I think the no.1 in my list is to get the proper weight and buoyancy control.

Last dive I had trouble sinking at first, it's my first boat dive and I am hiring the weights from the club which I had not used before, and with some mis-calculation maybe, I just can't get down. Keeping my buddy in the cold water for more than 5 minutes I managed to add some weight and got down.

I think i was actually a bit over weighted at that time because it seemed to be heavier than any time before. But when the air was low and I went to a shallower platform, I felt I have to swim hard to keep me in the same depth, I checked the BC and I believed it couldn't be defalte any more. This also made me quite nervouse because I am afraid that I could go up surface out of control. Late somehow I managed to find the neutral buoyancy back (don't know how..)..so this is big issue and as you all have said, I definately have every excuses to pratice more.

Skuttle
09-02-2008, 19:15
Don't feel bad, I'm struggling with this issue as well. This has been a very infomative thread. Love learning!

Ladyvalea
09-12-2008, 00:09
Proper breathing too. Inhale deeply. Pause (think of "h" sound not "k" sound. Keeps your air passage open).Exhale completely to expell CO2. Do it slowly and calmly. Not to be confused with skip breathing.

Also move deliberately and slowly. Don't waste energy pushing through the dense medium if there is no need.
I don't understand the "h" sound thingy?
ok, so I inhale all my air and exhale completely till empty lungs and inhale again?

freeski4ever
09-12-2008, 00:27
Lowering your SAC rate simply takes time. Its all about relaxing and getting comfortable with your environment and equipment. The more you dive, the better your SAC rate gets.

BillS
09-12-2008, 08:31
Great thread! Thanks for all the excellent tips. I wonder if PADI has ever thought about making "Air Consumption" a speciality course?

Warren
09-12-2008, 11:19
Also , if you're doing a long surface swim out, take time to relax and catch your breath befoere you go under.

Even from a boat I notice that with the bit of adrenaline you get from getting suited and jumping in leaves you a bit unsettled - So I take a few minutes even then to relax and go over the dive profile in my head, and engage in some light chatting to relax.

That can buy you an extra 10 minutes! Well, your buddy too, but I always try to cater to the biggest air user. Don't let anyone rush you to get diving, you'll be slightly out of breath, hurried and uncomfortable, and fall into some bad breathing habits.

Nice smooth big deep breaths, and be conscious of it for a few dives and you can train yourself to be more efficient.

My buddy dives a HP100, I'm still diving an AL80... We hit our turnaround point about the same time, and I am fatter than him... :smiley36:

stairman
09-12-2008, 12:22
experience is the best way to lower your sac rate.Relax,streamline and pull and glide if in a rocky location.Try frogkicking as well.I learned proper breathing technique in cave training.Breathe in fully,pause about 3 seconds without closing your throat,then exhale fully,pause for about 3 seconds and repeat.You dont have to lock the throat to pause and shouldnt.Many divers who are trained to exhale on ascent in an emergency run out of air before they reach the surface because they are expelling too much.A continuous hum,all the way to the surface is suficient,and can be done three times longer than trying to breathe out all the way up.Body size also matters as stated above.

stairman
09-12-2008, 12:26
Also remember that filling and dumping your BC wastes more air.Strive for nuetral buancy with slight increases on the inflator.If you put to much in and have to dump some out,thats air wasted that you cant breathe.

IndyDiver
09-12-2008, 12:57
Proper breathing too. Inhale deeply. Pause (think of "h" sound not "k" sound. Keeps your air passage open).Exhale completely to expell CO2. Do it slowly and calmly. Not to be confused with skip breathing.

Also move deliberately and slowly. Don't waste energy pushing through the dense medium if there is no need.
I don't understand the "h" sound thingy?
ok, so I inhale all my air and exhale completely till empty lungs and inhale again?

After you inhale deeply and have lungs full of air, you don't want your throat to close and seal them off. (More risk of lung expansion injury.)

If you are making a silent "H" sound to yourself during the pause between inhaling and exhaling, then your throat is open and air can escape from your lungs even if you are not actually trying to exhale at the moment.

If you are making a "K" sound, then the back of your tongue is pushed up and your throat is sealed off. (If you are drifting up at the time, this is definately not desireable)

James1010
09-12-2008, 13:27
Being in shape does help but I am 6-3 240 pounds and I do very well on my air. Just relax, and use the current.

James1010
09-12-2008, 13:28
But I did a drift dive at 60ft and I came up with the last people and I have 750 psi but there was this girl who had 2300 pounds left! Blew my mind and our dive time was over 60 minutes.

3rdEye
09-12-2008, 13:31
Being in shape does help but I am 6-3 240 pounds and I do very well on my air. Just relax, and use the current.


generally, how long are your dives on an AL80?

I'm 6'1 230, and most of my dives seem to end up around 45-50 minutes before I have to start heading up....used to be worse.

ReefHound
09-12-2008, 14:24
Great thread! Thanks for all the excellent tips. I wonder if PADI has ever thought about making "Air Consumption" a speciality course?

My LDS has an Air Consumption Clinic that incorporates all these tips and more, includes 3 hours of classroom where you learn many things and two dives at the lake where you put it into practice. Your SAC is measured on both dives and everyone sees some improvement, some have seen over 25% improvement. You don't get any kind of badge or card, it's purely for yourself to get better.

russp
09-12-2008, 14:46
Getting my weight and trim correct did more to get my air consumption under control than any breathing technique. In a 3mm full, I was carrying 10 pounds in my BCD pockets. Now I just carry 2 in each pocket and 2 by my tank valve and I'm level in the water without having to struggle to stay at depth or using a lot of air in my BCD to counter the extra weight.

Splitlip
09-12-2008, 19:59
Proper breathing too. Inhale deeply. Pause (think of "h" sound not "k" sound. Keeps your air passage open).Exhale completely to expell CO2. Do it slowly and calmly. Not to be confused with skip breathing.

Also move deliberately and slowly. Don't waste energy pushing through the dense medium if there is no need.
I don't understand the "h" sound thingy?
ok, so I inhale all my air and exhale completely till empty lungs and inhale again?

After you inhale deeply and have lungs full of air, you don't want your throat to close and seal them off. (More risk of lung expansion injury.)

If you are making a silent "H" sound to yourself during the pause between inhaling and exhaling, then your throat is open and air can escape from your lungs even if you are not actually trying to exhale at the moment.

If you are making a "K" sound, then the back of your tongue is pushed up and your throat is sealed off. (If you are drifting up at the time, this is definately not desireable)



Thanks Indy.
For part 2 of the question: Exhaling completely expells more CO2. Inhaling and pausing let's your avioli transfer more O2 to the lungs and blood.
This is most efficient. Hyperventilating is the least.

Splitlip
09-12-2008, 20:01
Being in shape does help but I am 6-3 240 pounds and I do very well on my air. Just relax, and use the current.


generally, how long are your dives on an AL80?

I'm 6'1 230, and most of my dives seem to end up around 45-50 minutes before I have to start heading up....used to be worse.

Need to consider the depth. :)

ReefHound
09-12-2008, 21:26
Another corollary to the breathing is to breathe through the diaphragm not your chest. This allows a fuller expulsion of CO2 and allows transfer in your lower lungs and use all of the alveoli.

cajunfla
09-15-2008, 05:11
I have an Oceanic Por Plus 2 computer....for the large numbers. The software calculates SAC rate if given the starting and ending PSI, cylinder size in cubic ft., and the 'working' PSI, amongst other info.

What is the working psi on an AL80N ? 3300PSI ?