Average Gas Consumption

[Blackcrusader]

Heh. After 35 dives started to calculate my SAC. Here is average for 3 last dives:

20,54 lpm \ 0,73 cfm for me. 97 kg / 213 pounds; 185 cm \ 6 ft 1 inch .
15,6 lpm \ 0,55 cfm for my wife. 56 kg \ 123 pounds; 159 cm \ 5 ft 2,5 inch.

You will improve a lot over time. One new diver here has gone from first dives in December 2020 with sac of 20l/min to less than 12l/min from changing the way he dives. But he has now done I think over 50 dives. Regular diving you can improve a lot for sure.

 

[Divin'Papaw]

I'm very late to this thread but better late than never. I just ran a calculation of my average RMV since getting my Perdix AI. That is over my last 119 dives. My average is 0.46 cfm. I've responded to the poll based upon that average.

I also ran MIN and MAX as well. My MIN was 0.32 cfm and my MAX was 0.61 cfm.

I was very late coming around to an air integrated computer but I sure do love the data it makes available to me!

 

[scubadada]

Wow, there have been 22 more responses to the 2016 poll since the last update. This is probably one of the most active polls on SB. Remember, you are able to change your vote in this poll if/when your average RMV changes. In the 2016 poll, the median and mode are both 0.5-0.59 cu ft/min. The weighted average also falls in this range. Thanks for all the responses and posts

See post #1 for imperial/metric conversion

 

[stepfen]

Heh. After 35 dives started to calculate my SAC. Here is average for 3 last dives:

20,54 lpm \ 0,73 cfm for me. 97 kg / 213 pounds; 185 cm \ 6 ft 1 inch .
15,6 lpm \ 0,55 cfm for my wife. 56 kg \ 123 pounds; 159 cm \ 5 ft 2,5 inch.

Welcome to scubaboard. We have somewhat similar figures (now I am 90kg and 190cm but I use to be around 110kg since I started diving in 2016 and until the end of 2019).
To get an idea what to expect here is how my SAC evolved over these years:

Year // No of dives // average SAC (lt/min)
2016 // 26 // 21.8
2017 // 29 // 17.1
2018 // 67 // 16.4
2019 // 90 // 14.7
2020 // 55 // 13.3

First year or so I was trying actively to reduce my SAC (tried breath control, singing while exhaling and whatever other bullsh*t recipe I would find around). Nothing really worked. Then thanks to scubaboard I stopped worrying about SAC itself and focused on diving as much as possible (to become more comfortable underwater) and tried to become a better diver (improve my buoyancy, my trim, my technique etc). Reduction of SAC followed naturally.

All the best

 

[Divin'Papaw]

Welcome to scubaboard. We have somewhat similar figures (now I am 90kg and 190cm but I use to be around 110kg since I started diving in 2016 and until the end of 2019).
To get an idea what to expect here is how my SAC evolved over these years:

Year // No of dives // average SAC (lt/min)
2016 // 26 // 21.8
2017 // 29 // 17.1
2018 // 67 // 16.4
2019 // 90 // 14.7
2020 // 55 // 13.3

First year or so I was trying actively to reduce my SAC (tried breath control, singing while exhaling and whatever other bullsh*t recipe I would find around). Nothing really worked. Then thanks to scubaboard I stopped worrying about SAC itself and focused on diving as much as possible (to become more comfortable underwater) and tried to become a better diver (improve my buoyancy, my trim, my technique etc). Reduction of SAC followed naturally.

All the best

That's awesome and I love the data to support it. I've found by experience that the important elements of keeping my SAC down are (1) getting/staying comfortable (2) working as little as possible (3) staying physically fit (4) deep, slow breathing.

Any changes to any of those factors drive up my SAC. If I'm cold, stressed, forced to work hard for some reason, in new equipment I'm not comfortable with, in a new environment I'm not yet comfortable with, etc. ... BAM ... SAC goes up sometimes markedly.

 

[scubadada]

Welcome to scubaboard. We have somewhat similar figures (now I am 90kg and 190cm but I use to be around 110kg since I started diving in 2016 and until the end of 2019).
To get an idea what to expect here is how my SAC evolved over these years:

Year // No of dives // average SAC (lt/min)
2016 // 26 // 21.8
2017 // 29 // 17.1
2018 // 67 // 16.4
2019 // 90 // 14.7
2020 // 55 // 13.3

First year or so I was trying actively to reduce my SAC (tried breath control, singing while exhaling and whatever other bullsh*t recipe I would find around). Nothing really worked. Then thanks to scubaboard I stopped worrying about SAC itself and focused on diving as much as possible (to become more comfortable underwater) and tried to become a better diver (improve my buoyancy, my trim, my technique etc). Reduction of SAC followed naturally.

All the best

Hi @stepfen

Great data, thanks for sharing. In 5 years and 267 dives, you have reduced your RMV by 40% and now have the same average RMV as our SB friend, @JimBlay

My gas consumption has always been pretty good, but I did not start following my RMV until I was at 443 dives. In the next 10 years and 1500+ dives, my yearly average RMVs have only varied by 0.04 cu ft/min (1.1 L/min). It appears my RMV was essentially fixed by the time I started calculating it. I am at the lower end of the tight range and variability has decreased a little.

 

[stepfen]

One important factor that kept my SAC high for the first year or so was me worrying about it too much. Then I realized that ending a dive a bit earlier than the rest was not a huge deal. This, together with getting more comfortable and gradually better technique were for me the most important factors at the beginning.

Nowadays I agree with all of the factors @JimBlay mentioned above and I would add (at least for me) that diving solo also has huge (positive) impact to my SAC.

When with a buddy (or even worst in a group), I simply can't relax enough. As I said I am a (relatively) big guy and I hate being disturbed but also disturb other people. When there are divers around me I constantly worry that I am disturbing somebody or that I will get disturbed (eg squeezed to the reef). Also when group diving, one needs to follow the group which usually means chasing the freaking dive guide. Do they do it on purpose (swim fast, make customers finish their air faster, finish dive faster, go home faster) or is it just my impression?

When I dive solo I am in paradise - all by myself

 

[ATJ]

Another factor for SAC/RMV is not getting cold. My SAC/RMV can skyrocket when I get cold.

I now pretty much dive all year around in my drysuit. I'm comfortable and my SAC/RMV stays pretty constant.

 

[DiveClimbRide]

When I'm cold my SAC is around 20lpm(0.7cfm) and when I'm warmish it goes as low as 13lpm(0.48cfm). My all time highest was running and swimming around in freezing water with no fins carrying rocks, and that was 38lpm(1.3cfm)

 

[BBking]

You will improve a lot over time. One new diver here has gone from first dives in December 2020 with sac of 20l/min to less than 12l/min from changing the way he dives. But he has now done I think over 50 dives. Regular diving you can improve a lot for sure.

Yeah, figured this out. At least, as the instructor said, you always have spare air in your wife's tank

Welcome to scubaboard. We have somewhat similar figures (now I am 90kg and 190cm but I use to be around 110kg since I started diving in 2016 and until the end of 2019).
To get an idea what to expect here is how my SAC evolved over these years:

Thanks! And thanks for data!

And about worrying about SAC. On the one hand, I heard about it: "Just dive, man! No worries" and this is true in my opinion, but on the other, thanks to worrying abount SAC, I read a lot of related literature and found out some good info.
E.g, about weighting Started with 10 kg in shorty suit, and now its only 5kg in 5mm full wetsuit. Or diff between steel\aluminium tanks etc
I mean, its better to know, than not to know.