Average Gas Consumption?

[DazedAndConfuzed]

Maybe you can bring a plastic bag with you, so instead of exhaling your breath out of the regulator, you can do it into the plastic bag, then inhale that again or another breath later. You can re-use the air since it still has good amount of oxygen left. Maybe suck it up with the opening facing up so that you don't suck up the CO2 that has sunk to the bottom of the bag.

 

[limeyx]

I know this is an open ended question and subject to many variables. I am a new diver and know my gas compsumption still needs improvement. I am diving mostly AA72's and am getting about 37 minutes on them with a max depth between 20 and 30 feet in about 53 degree water.
...
What are all you getting for time on a 80cf tank in cooler water.

Thanks

First off, what others have said --- don't sweat it too much, most people will expect a newer diver to have higher consumption for a while. As you get more confident, and comfortable, you will probably move less in the water, become more stable etc and use less gas.

One thing that for me affects gas consumption is how warm I am. I notice you are in Maine ? What kind of water temperatures and suit (wetsuit, drysuit) are you using ? Do you feel warm during the dive ?

There is a large variety of breathing rates, people are all over the map, but I think a "reasonable" SAC to shoot for would be in the 0.5 to 0.6 cubic feet per minute range at the surface.

That would mean at 33 feet you breathe 1.0 to 1.2 cft of gas per minute.

If you have a "full" 72cft fill in your tank, then that would correlate to a dive time of around 60-72 mins *if* you used all your air in the tank, so if you are allowing enough reserve gas to make a safe ascent with a buddy if they run out of gas, you should expect something shorter than that (depending on how much gas you reserve of course)

 

[smorneau]

Maybe you can bring a plastic bag with you, so instead of exhaling your breath out of the regulator, you can do it into the plastic bag, then inhale that again or another breath later. You can re-use the air since it still has good amount of oxygen left. Maybe suck it up with the opening facing up so that you don't suck up the CO2 that has sunk to the bottom of the bag.

Thanks for the usefull info, I think I will just put the bag over my head after reading this post!

 

[motorref]

I just got back from a week in the Bahamas, getting my daughters certified; On top of being a newbie I was VERY concerned about them, and was limited by a detached achilles tendon (surgery in a couple of weeks). I expected my air consumption to be pretty high, so I decided to use a 100 after a day or two, and I was pleasantly surprised by the amount of "extra" air I had left over, and I believe it all came down to being more relaxed as the week progressed. As many others have said so eloquently, this is the key to longer dives!

KevinL

 

[daz88]

Don't worry too much about it. Things come with time. Your SAC rate is one of them. Just make sure people your diving with know you're a new diver, and they'll know it will be a shorter dive. Everybody went through the same thing. Don't know anybody who had a great SAC rate from day one.
My kids both got their dive certs a few months back and my son kept asking me how a learned to make my air last so long. How long does it take? How do you breathe? How many dives until I can do it? and so on... And told him what everyone has been saying here. learn how to dive correctly, get more dives, relax. He's got about 30 dives now and his SAC rate has already improved alot from his first few dive weekends.
So just relax, you'll get there. Don worry about it too much. Just work on your skills and enjoy being under the water. relax...........

 

[exposure]

To add my 2 cents from my own small experience. Last year I did 30 dives in a row with my wife as a real beginner. At the beginning she told me 50 bars when I was about 90 to 100 bars, At the end of those dives she was about 10 bars from me. Put more dives on your belt and be comfortable under water. That's the key point for me. The good thing when you begin (like me) is that you have way to improve... Will be boring when there will be nothing to improve or learn

 

[aquaregia]

My SAC is insanely high. I warn people beforehand but I still feel bad.

Average depth of 25' I can do close to an hour on an AL80. My SAC is around 0.8cfm and my buddies have ranged between 0.35 and 0.7.

I also own small tanks, mostly 72s but a few 80s. Around here, tanks 100cf+ aren't uncommon. I ended up with some creative solutions, including doubling up my 72s or carrying an additional stage, all of which were complete overkill for the situation. I discovered that in a wetsuit, I didn't really want to do a dive longer than an hour in 50F water, and neither did my buddies.

It's worth mentioning a few things about the 72s though. One is that theyre often out of + rating, and so only get filled to 2250psi or 65cf. The next is that, due to the lower service pressure, if you leave a 500psi reserve*, you only have 78% of your tank to use, as opposed to the 83% in an AL80 or 86% of an HP100. This means that, if everyone plans to surface with 500psi, the guy with the LP72 has 50cf, the AL80 has 65cf and the HP100 has 85cf. It's not way different, but it is something to realize.


* NWGratefulDiver.com

 

[smorneau]

My SAC is insanely high. I warn people beforehand but I still feel bad.

Average depth of 25' I can do close to an hour on an AL80. My SAC is around 0.8cfm and my buddies have ranged between 0.35 and 0.7.

I also own small tanks, mostly 72s but a few 80s. Around here, tanks 100cf+ aren't uncommon. I ended up with some creative solutions, including doubling up my 72s or carrying an additional stage, all of which were complete overkill for the situation. I discovered that in a wetsuit, I didn't really want to do a dive longer than an hour in 50F water, and neither did my buddies.

It's worth mentioning a few things about the 72s though. One is that theyre often out of + rating, and so only get filled to 2250psi or 65cf. The next is that, due to the lower service pressure, if you leave a 500psi reserve*, you only have 78% of your tank to use, as opposed to the 83% in an AL80 or 86% of an HP100. This means that, if everyone plans to surface with 500psi, the guy with the LP72 has 50cf, the AL80 has 65cf and the HP100 has 85cf. It's not way different, but it is something to realize.


* NWGratefulDiver.com

Thanks, this is good info. I never concidered the "+" rating. I always thought they were 72's without the "+" rating. Maybe it's time to buy that used HP100 sitting at my LDS. I have not got a BP/W YET, so doubling is not an option.

 

[dumpsterDiver]

....

If you are in a group and are using air quicker than everyone else, stay a couple of meters above them- it makes a difference.

This is incredibly bad advice and if you did it to me you would not get invited to dive with me again. I absolutely hate having to roll over, look up, destroy my underwater night vision and get water up my nose just because some UW clown wants to play the "bird of prey- dive-buddy-trick". Stay with your buddy and in Maine, you are going to be close.

If you are big and strong enough, but a larger, heavier tank.. 72's are way to small for my liking, especially in cold water where it is harder to swim and metabolism goes up as your body tries to stay warm.

 

[James R]

Thanks, this is good info. I never concidered the "+" rating. I always thought they were 72's without the "+" rating. Maybe it's time to buy that used HP100 sitting at my LDS. I have not got a BP/W YET, so doubling is not an option.

That's not a bad idea, honestly.

I love my Faber HP100s...they are about the same size as an AL80, but obviously provide a good bit more air and I don't need any weight to dive them in a 5mm full suit & hooded vest (with aluminum backplate and wing) and I can go only 4lbs with my drysuit (or none with steel plate). In single tanks my RMV/SAC is usually between .45 and .6 depending on the dive and what treasure(s) I am working to recover. This means I finish most dives with well over 1000 and often 15-1700psig. Like TSandM, I can often get two dives on one of them.

I have tried the Worthington HP100s and did not like them. They are shorter, but more negative & tend to make me want to turtle much more than the Faber tanks. A lot of people I know have them and like them just fine, though.