air consumption, what to expect?

[P67000]

I logged a few informations about my air consumption. I was really disappointed by my latest results, mostly because I felt I was ruining the dives of everyone else. Of course, I am a newer diver, so I hope there is some space for improvement. But... how much? Should I expect dramatic change in consumption as I get more experience, or will I get stuck with bad results because of physiology? (lung size?)

32 minutes at a max depth of 39 feet, rather flat (colder water)
47 minutes at a max depth of 52 feet, but average probably around 30 (colder water)
49 minutes at a max depth of 35 feet, shallower at the end
40 minutes at a max depth of 32 feet, same site
29 minutes at a max depth of 103 feet (it was a wreck, we rather followed the deck, I'd guess it was flat but a little above the lowest point)
26 minutes at a max depth of 92 feet (same as above)
41 minutes at a max depth of 69 feet (I basically just sit at the bottom doing buoyancy exercices)
32 minutes at a max depth of 50 feet (rather flat bottom)

In all those case, I ended up on the reserve (in some case, a little too much inside for comfort, like 300 psi). I have read advice on how to help with air consumption, but nothing about what to expect. I mean, what is "average", what is "ok" and what kind of improvement have you witnessed between beginner divers and experienced ones?

 

[tracydr]

These don't look that bad, what kind of tank, exposure suit, water temperature. How large are you? What were the dive conditions? Did you have a surface swim, currents?

 

[DivemasterDennis]

There is no "average" air consumption, and there are variables with an individual diver. However, almost everyone decreases air consumption with experience, especially if you dive regularly. Different conditions, activities, temperature, and general health all impact air consumption. So too does you level of buoyancy control, body position control, streamlining, and equipment used. My experience was that for the first few dives I could do maybe 40 minutes at 40 feet on a 80 cu ft tank. Now after nearly 1000 dives I can easily double that (or more). The same is true at most depths- much less air use as a veteran than as a rookie, but I still have those dives where I am a bit excited, work a bit to get position for a photograph, etc. where air consumption is more limiting than ndl time. Monitor your gauges regularly, don't worry about air consumption, and consider these tips from our first book, The Scuba Snobs' Guide to Diving Etiquette:
Avoid Being an air sucker....a. Check you weighting...b. Trim your buoyancy often...c. Move less...
d. Stay a few meters above the rest of the group . More detail in the book. You will be fine. Happy Diving from the Scuba Snobs!
DivemasterDennis

 

[gcarter]

I have no idea how typical or atypical I am, but I am an air hog and my consumption is all over the place. Here is what I have been doing this year. Overall, the trend is slightly down, and I'm having fun. So I track it but don't sweat it. It is what it is

The thing that I see very clearly in my results is that my consumption goes up with a new site or buddy or experience (ie drift). The more I do a site, the better my consumption in that situation. These dives are in water ranging from 3C to 22C, most under 15C.

My son with around the same number of dives uses about half the air I do. Dive 57, last Wednesday, I did 38 minutes on an AL80 finishing with 700 psi. Somebody else on the same dive did 72 minutes and finished with 800 psi.



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[TD]Divetime[/TD]
[TD]MaxDepth[/TD]
[TD] DepthAvg [/TD]
[TD] RMV [/TD]
[/TR]
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[TD]22[/TD]
[TD]27[/TD]
[TD]18.2[/TD]
[TD]7.49 [/TD]
[TD]0.87 [/TD]
[/TR]
[TR]
[TD]23[/TD]
[TD]31[/TD]
[TD]18.8[/TD]
[TD]10.83 [/TD]
[TD]0.92 [/TD]
[/TR]
[TR]
[TD]24[/TD]
[TD]29[/TD]
[TD]15[/TD]
[TD]7.41 [/TD]
[TD]1.18 [/TD]
[/TR]
[TR]
[TD]25[/TD]
[TD]24[/TD]
[TD]17.8[/TD]
[TD]12.18 [/TD]
[TD]1.11 [/TD]
[/TR]
[TR]
[TD]26[/TD]
[TD]40[/TD]
[TD]11.7[/TD]
[TD]5.87 [/TD]
[TD]0.89 [/TD]
[/TR]
[TR]
[TD]27[/TD]
[TD]38[/TD]
[TD]14.8[/TD]
[TD]7.09 [/TD]
[TD]0.91 [/TD]
[/TR]
[TR]
[TD]28[/TD]
[TD]39[/TD]
[TD]14.8[/TD]
[TD]8.90 [/TD]
[TD]0.77 [/TD]
[/TR]
[TR]
[TD]29[/TD]
[TD]30[/TD]
[TD]15[/TD]
[TD]11.07 [/TD]
[TD]0.98 [/TD]
[/TR]
[TR]
[TD]30[/TD]
[TD]26[/TD]
[TD]16.8[/TD]
[TD]13.45 [/TD]
[TD]1.06 [/TD]
[/TR]
[TR]
[TD]31[/TD]
[TD]40[/TD]
[TD]7.3[/TD]
[TD]5.06 [/TD]
[TD]0.90 [/TD]
[/TR]
[TR]
[TD]32[/TD]
[TD]45[/TD]
[TD]8[/TD]
[TD]6.06 [/TD]
[TD]0.82 [/TD]
[/TR]
[TR]
[TD]33[/TD]
[TD]44[/TD]
[TD]12.7[/TD]
[TD]5.30 [/TD]
[TD]0.86 [/TD]
[/TR]
[TR]
[TD]34[/TD]
[TD]30[/TD]
[TD]12.5[/TD]
[TD]6.40 [/TD]
[TD]1.21 [/TD]
[/TR]
[TR]
[TD]35[/TD]
[TD]18[/TD]
[TD]12.6[/TD]
[TD]6.30 [/TD]
[TD]0.88 [/TD]
[/TR]
[TR]
[TD]36[/TD]
[TD]22[/TD]
[TD]24.9[/TD]
[TD]14.60 [/TD]
[TD]0.72 [/TD]
[/TR]
[TR]
[TD]37[/TD]
[TD]22[/TD]
[TD]25[/TD]
[TD]14.90 [/TD]
[TD]0.94 [/TD]
[/TR]
[TR]
[TD]38[/TD]
[TD]21[/TD]
[TD]25[/TD]
[TD]10.70 [/TD]
[TD]0.83 [/TD]
[/TR]
[TR]
[TD]39[/TD]
[TD]24[/TD]
[TD]36.7[/TD]
[TD]19.60 [/TD]
[TD]0.96 [/TD]
[/TR]
[TR]
[TD]40[/TD]
[TD]36[/TD]
[TD]11.5[/TD]
[TD]6.30 [/TD]
[TD]0.88 [/TD]
[/TR]
[TR]
[TD]41[/TD]
[TD]22[/TD]
[TD]8[/TD]
[TD]4.90 [/TD]
[TD]1.02 [/TD]
[/TR]
[TR]
[TD]42[/TD]
[TD]40[/TD]
[TD]7.4[/TD]
[TD]4.90 [/TD]
[TD]0.91 [/TD]
[/TR]
[TR]
[TD]43[/TD]
[TD]31[/TD]
[TD]7.4[/TD]
[TD]4.80 [/TD]
[TD]0.90 [/TD]
[/TR]
[TR]
[TD]44[/TD]
[TD]22[/TD]
[TD]25.8[/TD]
[TD]12.10 [/TD]
[TD]1.11 [/TD]
[/TR]
[TR]
[TD]45[/TD]
[TD]32[/TD]
[TD]32[/TD]
[TD]13.60 [/TD]
[TD]0.79 [/TD]
[/TR]
[TR]
[TD]46[/TD]
[TD]34[/TD]
[TD]12.7[/TD]
[TD]7.10 [/TD]
[TD]0.93 [/TD]
[/TR]
[TR]
[TD]47[/TD]
[TD]35[/TD]
[TD]8.7[/TD]
[TD]5.40 [/TD]
[TD]1.05 [/TD]
[/TR]
[TR]
[TD]48[/TD]
[TD]42[/TD]
[TD]8.3[/TD]
[TD]4.80 [/TD]
[TD]1.04 [/TD]
[/TR]
[TR]
[TD]49[/TD]
[TD]27[/TD]
[TD]28.7[/TD]
[TD]18.70 [/TD]
[TD]0.88 [/TD]
[/TR]
[TR]
[TD]50[/TD]
[TD]28[/TD]
[TD]21.2[/TD]
[TD]14.90 [/TD]
[TD]0.89 [/TD]
[/TR]
[TR]
[TD]51[/TD]
[TD]35[/TD]
[TD]28.7[/TD]
[TD]17.01 [/TD]
[TD]0.92 [/TD]
[/TR]
[TR]
[TD]52[/TD]
[TD]49[/TD]
[TD]12.5[/TD]
[TD]7.12 [/TD]
[TD]0.71 [/TD]
[/TR]
[TR]
[TD]53[/TD]
[TD]47[/TD]
[TD]8.4[/TD]
[TD]5.33 [/TD]
[TD]0.90 [/TD]
[/TR]
[TR]
[TD]54[/TD]
[TD]40[/TD]
[TD]8.4[/TD]
[TD]4.66 [/TD]
[TD]0.79 [/TD]
[/TR]
[TR]
[TD]55[/TD]
[TD]28[/TD]
[TD]20.7[/TD]
[TD]14.39 [/TD]
[TD]0.94 [/TD]
[/TR]
[TR]
[TD]56[/TD]
[TD]37[/TD]
[TD]17[/TD]
[TD]9.57 [/TD]
[TD]0.80 [/TD]
[/TR]
[TR]
[TD]57[/TD]
[TD]38[/TD]
[TD]7.7[/TD]
[TD]4.71 [/TD]
[TD]1.06[/TD]
[/TR]
[/TABLE]

 

[P67000]

These don't look that bad, what kind of tank, exposure suit, water temperature. How large are you? What were the dive conditions? Did you have a surface swim, currents?

The "colder" ones were around 55 °F, the other ones were with 77°F. 5mm suit (or was it 3? It was rental gear and I am not totally sure) and AL80. My main concern was that I ended up with 500 psi when I got a glimpse of other divers with much more air, and my instabuddy, a short asian woman, was around half-time... I felt guilty, even if I couldn't do much about it.

@divemasterdennis: I have already cut my weighting by more than half since I started diving. There might be some room for improvement, but 10 pounds for a 5'8 in the sea and said gear doesn't seem outlandish... especially when I'll come back to freshwater. Moving less and relaxing more are the way to go. Staying above the group well... As a last resort I guess it's the only way.

 

[DukeAMO]

I got my SAC rate to drop dramatically within a few dives by moving/wiggling/fighting the water less, and relaxing more. I went from using my air 20% faster than DH to using less air than him just by doing that. I know I can get better simply by practicing that, as well as finding sites with less current that are easier to navigate without kicking too much. ;-)

 

[TSandM]

Well, if that was an Al80, and trying to use the data you gave for dives where your depth was fairly constant, I come up with an RMV of .6 to .9, which isn't bad for a new diver. You can probably cut that by a good 30%, when you become more relaxed and more stable in the water. .7 is quoted as a fairly average gas consumption for an adult male, although I know a lot of adult males whose RMV is lower than that.

The bottom line is that you use what you use -- bigger people will use more, people who swim fast will use more, and people whose diving technique is very efficient will use less.

 

[Scuba_Noob]

The more you dive, the more comfortable you will get in the water, and that will cause your air consumption to decrease. Your buoyancy will improve, and fewer adjustments will have to be made throughout the dive. Also, remember that diving is about the journey, not the destination. Dive slow and relaxed, not fast.

I suggest recording your air consumption info in your log book to see how it decreases. By around 50 dives, it should be pretty stable (it might change when playing with new equipment). Try this site SAC Calculator

From my first few dives to my 50th or so dive, I went from an SAC average of around 0.75 down to about 0.5, and it's been really stable since.

 

[spectrum]

I logged a few informations about my air consumption. I was really disappointed by my latest results, mostly because I felt I was ruining the dives of everyone else. Of course, I am a newer diver, so I hope there is some space for improvement. But... how much? Should I expect dramatic change in consumption as I get more experience, or will I get stuck with bad results because of physiology? (lung size?)

32 minutes at a max depth of 39 feet, rather flat (colder water)
47 minutes at a max depth of 52 feet, but average probably around 30 (colder water)
49 minutes at a max depth of 35 feet, shallower at the end
40 minutes at a max depth of 32 feet, same site
29 minutes at a max depth of 103 feet (it was a wreck, we rather followed the deck, I'd guess it was flat but a little above the lowest point)
26 minutes at a max depth of 92 feet (same as above)
41 minutes at a max depth of 69 feet (I basically just sit at the bottom doing buoyancy exercices)
32 minutes at a max depth of 50 feet (rather flat bottom)

In all those case, I ended up on the reserve (in some case, a little too much inside for comfort, like 300 psi). I have read advice on how to help with air consumption, but nothing about what to expect. I mean, what is "average", what is "ok" and what kind of improvement have you witnessed between beginner divers and experienced ones?

There are many variables that enter into your consumption rate. I assume you know that you will consume faster at deeper depths. That being said you can enjoy longer dives for now by staying shallower. That extended bottom time and associated practice can pave the way to a better rate.

Using TSandM's numbers 60-90 is common for your dive count and where some divers will be. I also agree that you have a real good shot at knocking 30 or so points off that score. Some of it will be physiology but from what I have seen much more is comfort, good form and technique.

Comfort: Just keep diving in your comfort zone. Experience is a wonderful thing and it alone will make a difference.

Good Form: Make sure your weight and horizontal trim are dialed in. More here. Be sure your gear fits.A poorly fit suit will chill you. A poorly fit BC will leave you fussing and diving like a bag of worms.

Technique: Think fish! Dive at a comfortable pace. You need not be a moving like a torpedo. Kick glide kick glide. If you have buddies leading fast dives you have identified a contributor to high usage. Put your arms someplace, at your side crossed on your chest ot locked forward. You do not want to be flapping and waving. That's a waste of energy and makes you a menace.

Breathe at a natural pace. This will vary with where you are in the dive, current and depth. The important thing is to make sure you breathe deeply, exhale fully and inhale deeply, not exaggerated just deliberately. This allows you to relax and you will find a comfortable breathing rate. Carbon dioxide retained when exhaling incompletely is the trigger to the need to breathe so exhaling cannot be overstated.

Even with progress you can expect your rate to vary by .2 or more. Mood, exertion and so forth will all drive variation.

It's probably worth mentioning that you consider respecting the limits of your air supply a little more. If those last few hundred PSI were burned messing in the shallows, no big deal, If they were your safety stop that's another story. I realize you are trying to manage the impact on others but reserves must be maintained.

Pete

 

[P67000]

First, thank you all for your answers. They're really appreciated. :thumbs-up

There are many variables that enter into your consumption rate. I assume you know that you will consume faster at deeper depths. That being said you can enjoy longer dives for now by staying shallower. That extended bottom time and associated practice can pave the way to a better rate.

Yes. My worries were caused because we dove on wrecks, and you really can't deviate from the deck depth, maybe by a few feet above the rest of the group but not much more. And perhaps because I buddied with someone with great air consumption despite her lack of experience (and maybe half my weight also) and could only compare with her and the DM... Because during my training sessions, it didn't appear to be _that_ bad to cause concern, or maybe I just didn't pay attention yet.

Using TSandM's numbers 60-90 is common for your dive count and where some divers will be. I also agree that you have a real good shot at knocking 30 or so points off that score. Some of it will be physiology but from what I have seen much more is comfort, good form and technique.

OK, I was looking for that sort of numbers, not to set a goal but to know that I have room for improvement with experience and when I'll get used to new conditions.

It's probably worth mentioning that you consider respecting the limits of your air supply a little more. If those last few hundred PSI were burned messing in the shallows, no big deal, If they were your safety stop that's another story. I realize you are trying to manage the impact on others but reserves must be maintained.

In all cases but one (and that was an error, I realize this) we turned at the right time, I guess. I signalled half time and 1,000 psi to the DM. I would have thought that going up I would drop the air consumption, but it was apparently not the case during most of these dives. Maybe I just breathed heavily because of the stress of thinking I am near my reserve... Going for slow and deep breath is definitely something I should do.