Air Consumption Curiosity

[Tigerman]

Im quite steady at < .5 cft/min with a shorty, al80 and my camera rig. Introduce the drysuit and things change for a coupe of reasons - first of all more insulation means more weight to push around. Also when I dive dry I tend not to be just swimming around looking at and taking pictures of cool stuff but actually work in some way, shape or form and the sac can easilly get to .8-.9 cft/min depending on what Im doing..

 

[Soggy_Diver]

About .5 cubic ft/min in warm water.
About .7 cubic ft/min in cold water.

 

[RickyF]

My RMV runs between .32 - .38 for most dives.

 

[bygolly]

When I started out I was around 1 cu.ft/min. Now with 500+ dives I find I am .45 cu.ft/min in warm water, .65 cu.ft/min in cold.

 

[TSandM]

The number widely quoted as the average for a standard-sized adult male is 0.7 cfm. Women or smaller men will use less; larger people tend to use more.

Stress, exertion, cold, streamlining -- all can have very significant impacts on consumption. On one of my early dives practicing running line, I doubled my consumption rate from my normal.

It is extremely dangerous to try to lower your SAC rate beyond a certain point, because it can only be done by allowing the blood CO2 levels to rise. This increases narcosis and tends to produce anxiety and lower the panic threshold. You breathe what you have to; you learn to be efficient, streamlined and relaxed, and then if you need to, you buy a bigger tank

 

[DivemasterDennis]

Pyramid 65, apart from knowing your tank size, it's hard to rate your air consumption rate. I do not all dives were shall ( less than 30 feet. always remember you air consumption increases at depth. If your dives were at 50 to 60 feet instead of the depths they were, you consumption would be about 1 and 1/2 time what is was, all else being equal. Rathe3r than wonder "where you stand" get in the habit of logging all your dives, and include depth bottom time and air in and air out numbers. In nearly 1000 dives I have never asked anyone for their sac rate. Really. It is not a disqualifier for me. I'll dive with just about anyone who will monitor their gauges, stay buddy close throughout the dive, and stick to the dive profile.
DivemasterDennis

 

[boulderjohn]

The number widely quoted as the average for a standard-sized adult male is 0.7 cfm. Women or smaller men will use less; larger people tend to use more.

There was a recent thread (that I will leave unidentified) in which people were talking about their dive times with AL 80s. A significant portion of the people responding said they routinely got 80-90 minute dives with their AL 80s, and they said just about everyone who dives with them gets about the same. They emphasized that these are not extraordinary divers--just the average run of the mill diver using the same operators they do. (Their point was that there should never be any need for anyone to use larger capacity tanks.) I suggested that these dives had to have a pretty shallow average depth, but that comment was not well received. I did the math. That was not well received, either.

 

[Tigerman]

There was a recent thread (that I will leave unidentified) in which people were talking about their dive times with AL 80s. A significant portion of the people responding said they routinely got 80-90 minute dives with their AL 80s, and they said just about everyone who dives with them gets about the same. They emphasized that these are not extraordinary divers--just the average run of the mill diver using the same operators they do. (Their point was that there should never be any need for anyone to use larger capacity tanks.) I suggested that these dives had to have a pretty shallow average depth, but that comment was not well received. I did the math. That was not well received, either.

I just went through the past 32 dives Ive done with AL80 tanks to fill in the air consumptions from my log and out of those dives my consumption has been running at .35-.50 cuft/min depending on how cold Ive felt and how much current theres been, most of them .40-.45 cuft/min.
There was five of those dives running at 70-77 minutes and what they had in common, other than (on average) a .39 cuft/min consumption with an ammount of spare gas that would make 80 minutes fully, safely doable with atleast 50 bar left in the tank is that the average depth where between 8,5 and 10,5 meters (average of the average depths 9.15 meters) - which is suspect is exactly in line with the math you did before..

 

[The Kraken]

Mine runs, on an average dive, from about .45 to .50.

Stressful dives more, needless to say.

 

[bradells]

There was a recent thread (that I will leave unidentified) in which people were talking about their dive times with AL 80s. A significant portion of the people responding said they routinely got 80-90 minute dives with their AL 80s, and they said just about everyone who dives with them gets about the same. They emphasized that these are not extraordinary divers--just the average run of the mill diver using the same operators they do. (Their point was that there should never be any need for anyone to use larger capacity tanks.) I suggested that these dives had to have a pretty shallow average depth, but that comment was not well received. I did the math. That was not well received, either.

I can easily do a 90min dive on half an AL80. Max depth 70ft, with ~70 of those minutes at 20ft ..... In nice warm Caribbean water.

This was on the last invasion, I came up because when I looked up to the boat, I saw most people looking over the side at me, figured it was time to come up.

There was an OW class going on at the same time on that boat, and they lasted longer than I would have on my first few dives (45min @ 20ft)

BRad