Air consumption

[archer1960]

that and pint isn't really something used in scuba so I didn't use it.... We think in lbs of lift and CF of gas, vs L of gas and kg of lift....

Storker I wasn't attacking your profiles, merely commenting that it is highly unlikely for the increased air consumption to be due to the increased bubble size of your suit, but more an actual increase in your SAC rate due to the conditions, which is perfectly normal

The only reason I mentioned pints and pounds is that they are relatively small units, which Americans will be familiar with. They know how big (how much volume) a pint of air is, and then can get a feel for how much (or little) it takes to change lift by a pound. A cubic foot and its 60+ lbs is too big of a unit to be useful for that discussion.

 

[vman]

Please understand that this will not effect your air consumption in the least, it simply changes the ease of breathing of the regulator. It does not change the amount of gas you breath.

I don't understand.. how does the regulator change ease of breathing without controlling air flow? If it constricts air flow by reducing the diameter of an opening, then theoretically speaking the volume of air delivered should be lower ( assuming the same amount of suction force ). Maybe I'm wrong, but that's my thinking.

 

[Diver0001]

Work of breathing (easier or harder) doesn't change the amount of air that goes into full lungs. It just changes how much effort you need to put into getting that air.

R..

 

[gfaith]

I don't understand.. how does the regulator change ease of breathing without controlling air flow? If it constricts air flow by reducing the diameter of an opening, then theoretically speaking the volume of air delivered should be lower ( assuming the same amount of suction force ). Maybe I'm wrong, but that's my thinking.

There is your answer! When you adjust, as you stated, you increase the amount of suction force needed. When the driver gets his adjustment correct he decreases the WOB, and that, in theory, would help with lowering gas consumption.

 

[CT-Rich]

I was diving a couple of days ago and on my first dive I was video taping the dive site and trying to cover as much ground as I could to find the target spot I was looking for. I was using my 100 bottle and was on the bottom for 37 minutes. Later I made a second dive with a similar profile, but because I was out batteries I was just puttering around, hit neutral on my BCD, did a slow modified frog kick that is very low energy and toodled along at without a care in the world. I had the same bottom time with a 72 as I did with the 100. The oldsters probably couldn't tell you why they have better sac's because they are just comfortable and zero stress. I sympathize with you I am a really big guy (6' 7' and 220lbs) and I look at the these little waifs that can do two dives on a 50....

 

[scubadada]

I know this has been talked to death, but still...

I have around 100 dives all in Cozumel and I am AOW cert. Recently I dove one week with other divers that have been diving 30+ years. They were all very big men. My dive buddy and I are both very fit. My buddy watched me dive and says I rarely move a muscle except of course when I need to fin. my hands are always clasped or folded and arms tucked close. Nothing hanging from my wetsuit. In other words my trim is good. The more experienced divers have their hands outstretched or out to the sides or basically just whatever they feel like doing. They are as or more active as I am. In fact a couple of them were zooming around with giant cameras making sure to get in everyone's way to "get the shot". We were all on nitrox. They all consistently use less air! I was up 10 to 15 minutes earlier every time. (about an hour total most dives). I think I dive fairly relaxed. I cant figure out why I am using more air!

Hi mridude,

I just noticed that you are the same OP as for the weighting thread I just replied to http://www.scubaboard.com/forums/basic-scuba-discussions/512597-trying-get-my-weight-right.html I would imagine that your air consumption will improve for many of the same reasons your weight requirement will decrease, more dives, more experience, improved technique.

As has been pointed out, it may help you to calculate your SRMV (or SAC) to give you a better idea of where you are now, what variables affect your air consumption, and how you improve in the future.

I did not start tracking my SRMV until about 450 dives, but have calculated it for the last 5 years/nearly 600 dives. My air consumption has improved very modestly during that period, less than 10%, but I was doing reasaonably well when I started monitoring. It's remarkable how little air consumption actually varies, for me, the largest variables are warmth, and to a lesser extent, effort. When I'm cold while diving, my air consumption is predictably higher. My average SMRV is O.37 cu ft/min and 95% of my SMRVs are between 0.29 and 0.45. This information is extremely valuable to me for gas planning.

Best of luck with your weighting and gas consumption, best of all, have fun getting there