Air Consumption

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TheSherpa

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Messages
39
Reaction score
21
Location
Maine
# of dives
25 - 49
Just did my longest dive (my 5th dive). I managed to get 57min from a ~2900psi fill al80. Returned with 300psi. 56°water at an average depth of 25ft. Does this seem high? How long do more experienced divers see? I was towing our dive flag, and had to pickup a rock to carry with me the last 5min (just barely under-weighted).
 
Your consumption is on the high side of normal. You consumed 71.7 cubic feet of gas with a SAC of 26.0 PSI per minute and a RMV of 0.716 cubic feet per minute.

Lots of factors contribute, physical size, water temp, stress levels, workload, experience. As you dive more it will improve naturally so keep diving.
 
It will get better as you dive more. Don’t worry much about it. Better trim and streamlined gear helps.
 
Your consumption is on the high side of normal. You consumed 71.7 cubic feet of gas with a SAC of 26.0 PSI per minute and a RMV of 0.716 cubic feet per minute.

Lots of factors contribute, physical size, water temp, stress levels, workload, experience. As you dive more it will improve naturally so keep diving.

Hi @TheSherpa

This is a common question. You may find this thread useful, Average Gas Consumption There are many other threads on the topic, the search function at the top of each page can be very useful.

Very best and good diving

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Just did my longest dive (my 5th dive). I managed to get 57min from a ~2900psi fill al80. Returned with 300psi. 56°water at an average depth of 25ft. Does this seem high? How long do more experienced divers see? I was towing our dive flag, and had to pickup a rock to carry with me the last 5min (just barely under-weighted).
I am of the belief that your air consumption is what it is. Fixating on it is counter productive.

As you dive more and get more comfortable and skilled, it WILL come down. Some of us are destined to always have a high consumption simply down to size (there is no way a 6'3 guy can be as efficient on gas as a 5'4 woman). I have come to accept that if I want to match dive times , I generally need a larger tank (renting a 15l on holiday if 12l is the norm).
 
Dive times vary greatly based on a lot of things. Body weight, relaxed level during dive, depth, water temps, currents to name a few. In the Caribbean, I have dives regularly go over 60 min.

My longest dive ever was 1:19 – 80 tank 80/20 air, Cozumel, no more than 90 ft, 84 F water temp, in top shape, 6# of lead, and a 7-8 min safety stop. And my last trip to CZ Aug 2019, every dive was 60+ except one dive.

In the colder waters in Socorro this year a ‘long dive’ was 53 minutes… 80 tank 32 nitrox, 75-77 water temp, still in top shape, 10# of lead a 5 mil wetsuit, 3-5 min safety stops, I do not think I ever broke 100 ft.

57 minutes is good, but not unheard of.
 
As a beginner you may be better served concentrating on some fundamental skills rather than air consumption. Most beginners carry way too much lead. It’s important to be properly weighted with minimal air in your BC at depth. Work on your trim and position in the water column (without fiddling with your BC inflator). Slow down. Focus on the dive and your surroundings. Most beginners are easily distracted. Moreover, they are in perpetual motion with bicycling legs, flailing arms, waving hands and pivoting heads. Be calm, relaxed and in control. By default, addressing these basic skills will improve your air consumption. Unfortunately, I was completely oblivious as a newbie. You can concentrate on breathing more effectively, deeply and efficiently AFTER you become a more experienced and confident diver. Good luck!
 
What Marie said. Just about everyone consumes more gas as a new diver than they do after they gain some experience. Everyone's baseline is different, but your RMV/SAC will almost certainly drop as you do more diving. Plus, you were towing a dive flag, which definitely adds a bit of task loading given it was only your fifth dive.

As you gain more experience, if you find that you are the rate-limiting factor in your dive group, just get a bigger tank. Until then, just dive, work on your trim, buoyancy, and weighting, and have fun! You didn't run out of air, and that's by far the most important issue.
 
I would agree with all the above. With just 5 dives under your belt, air consumption should be pretty far down your list of things to work on. Your SAC will improve just by diving more, but you will reach a point where it no longer improves as you reach the limit of your body can do. Big lungs will use more air than little lungs. And skip breathing and other such foolishness is not the answer. If you have a mismatched SAC rate with you dive buddies that is the reason the dive gods made larger tanks. Enjoy diving as it just gets better the more you do it!
 
I pretty much stopped caring how long I can make a tank last or if I can cut a pound or two of weight. About the only thing I do care about is did my buddy and I have fun.

That being said; Somewhere around dive #30, I figured out that "breath normal" isn't possible when you actually think about breathing. Also about the same time if figured out the true meaning of "never hold your breath". When I thought about "breath normal" I was actually taking longer and deeper breaths than what is actually normal. When I stopped thinking about breathing, stop trying to conserve air, accepted my air consumption is what it is, it actually improved quit a bit. I still consume more air than my less experienced wife/dive buddy so I tend to dive slightly shallower than her, try not to drag dive flags, don't use reg. at the surface. My next step will be to replace my split fins with basic fins like my wife uses. Unless we're drifting. I need more kick cycles than she does.
 
https://www.shearwater.com/products/swift/

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