Average Gas Consumption

[wnissen]

Hi Scubadada,
Yes, I contributed. I hope eventually to improve my answer.

AMEN...

Typically on a caribbean dive, I go 60-70 minutes, ending with 500 psi

So you can't tell without knowing an average depth. The reason it's "surface" air consumption is that the increased pressure is divided out. An aluminum "80" contains about 2,300 liters of air at ambient temperature and pressure, with about 1900L remaining at a 500 psi reserve . If I have an RMV of 20 liters, I would be able to breathe for 95 minutes at the surface. At 20 meters I would breathe through the same 20 liters every minute, but since it would be compressed to 3 atmospheres my actual, unscaled consumption would be 60 liters per minute, so I'd only be able to dive for 32 minutes. Or 48 minutes at 10m.

If you sync dives to a computer, Subsurface will tell you what your RMV is if you supply the cylinder size. I can see at a glance that I pretty consistently use about 20L/min in 12C / 55F ocean water, and about 16L/min in warm lake water. I don't have enough tropical ocean dives to know that number, but it would be between the two. It's very helpful for dive planning.

 

[scubadada]

After diving with @scubadada last week I can attest that he actually breathes through gills behind his ears which accounts for his exceptionally low RMV.

Thanks for the comment, actually, our dives were controlled by my wife's gas consumption, she is doing better and better .

 

[scubadada]

Thanks @wnissen

Your RMV will improve with experience, improved buoyancy, trim, propulsion, and effort. It would be gratifying to follow your RMV from earlier in your diving career, until later. I did not start following my RMV until nearly 450 dives, it has improved only minimally since that time. I have always had a relatively good RMV, without any data, I attribute much of it to my competitive swimming career, starting at a very young age.

Good diving, Craig

 

[mcohen1021]

So you can't tell without knowing an average depth.

yeah, this convo is way over my head. I look at my pressure, depth and pc and just dive until I get out at 500 psi. I was just saying a typical carib dive for me is 60-70 min. Usually, I stay 85 or less.

 

[scubadada]

yeah, this convo is way over my head. I look at my pressure, depth and pc and just dive until I get out at 500 psi. I was just saying a typical carib dive for me is 60-70 min. Usually, I stay 85 or less.

There are many simple online calculators that will give you your RMV if you know your gas consumption, average depth, and cylinder characteristics. This is just one of them Surface Air Consumption Calculator | DiveBuddy.com.

To use your example, say you dived for 60 minutes, at an average depth of 60 feet, using an AL80 rated and filled to 3000 psi, and surfaced with 500 psi (used 2500 psi). Your RMV would be a very respectable 0.39 cubic feet per minute.

Some computers will give you your average depth in the on board log, some will require that you download your dives.

 

[arew+4]

I've got 4 additional data points for you, can't enter them, maybe you can.
Wife, same dive history as myself averages .30-.35
Children, 40 dives each. Last 10 dive range
Daughter 5'2" 100lbs .40-.47
Son 1 5'11" 180lbs .60-.70
Son 2 6'1" 215 lbs .70-.85

Size, Experience, Fitness. Seems to be the order of impact, based on my experience.

 

[scubadada]

I've got 4 additional data points for you, can't enter them, maybe you can.
Wife, same dive history as myself averages .30-.35
Children, 40 dives each. Last 10 dive range
Daughter 5'2" 100lbs .40-.47
Son 1 5'11" 180lbs .60-.70
Son 2 6'1" 215 lbs .70-.85

Size, Experience, Fitness. Seems to be the order of impact, based on my experience.

Hi @arew+4

Thanks for the reply. Each SB member is allowed only one vote in the poll, including me. My vote is in there, glad yours is too

 

[scubadada]

There has been another recent thread regarding gas consumption Fully exhale when diving? Breath control?. Following your RMV can give you feedback regarding changes you have made in buoyancy, trim, propulsion, effort, relaxation, and, even your breathing pattern

 

[Bob DBF]

I've got 4 additional data points for you, can't enter them, maybe you can.

Thanks for the reply. Each SB member is allowed only one vote in the poll, including me.

Or you could just share your secret of Scubaboard and have them join and answer the poll, and give their perspective. Not a good idea if they are young and might be led astray by those in the Pub.


Bob

 

[HDP]

Over 210 hours of diving:

Max = 35 l/min
Min = 9.3l /min
Avg = 13 l/min