Saving Air

[del_mo]

When I need to adjust my buoyancy by adding air, I do it manually in an effort to try and save tank air. My wife tells me I am actually wasting air doing it that way. Since I am seldom right (life is easier that way), I was wondering if anyone has an opinion on this topic.

 

[The Kraken]

I don't know if the term "wasting" it is exactly correct, but from where do you think you get the air in your lungs.

All things being equal, you are using a bit more air by blowing into your inflator hose because it requires energy and the creation of that energy requires air THEREFORE you are putting the same amount of air into your BC but also using that little bit of air required to generate the energy. Also, you're supposed to be exhailing very slowly when your reg isn't in your mouth so you're losing that air also.

Cancun Mark has in his signature a statement:
"There are two theories of how to argue with a woman, neither of which work."

 

[Scott Riemer]

If you're underwater the air is still coming from the same place. Looks like the Kraken and I posted about the same time. I agree with him, you're probably using more air.

 

[Charlie99]

In theory oral inflation could use less if it's just air you were going to exhale anyway. In real life, though, you probably use more because of breaking your normal breathing pattern.

In either case, the amount isn't much: 32 pounds of lift is 1/2 cubic feet, which even at 100' is only 2 cu ft of free gas.

It IS a good thing to orally inflate your BC often enough that you are comfortable using this alternate inflation method.

 

[DandyDon]

When I need to adjust my buoyancy by adding air, I do it manually in an effort to try and save tank air. My wife tells me I am actually wasting air doing it that way. Since I am seldom right (life is easier that way), I was wondering if anyone has an opinion on this topic.

She's right, you're wrong - again!
:lol: :lol3:​

 

[miketsp]

My guess is that with good technique - take a good breath, remove the reg being careful to rotate it mouthpiece down as you remove it, hold a few seconds to make the most of what O2 is in the breath, put 7/8 of it into the BC and then reinsert the reg using the final 1/8 of your breath to remove any water without needing to purge - then there may be a very slight gain. But I would bet that most divers would waste some air either clearing the reg or upsetting their steady breathing cycle so I think the net gain would be zero.
Then too you would have less fine control as you are trying to put the air in under abnormal buoyancy condition - full lungs. It really is easier to use the inflator...

 

[mempilot]

Just buy doubles.

 

[OE2X]

Just buy doubles.

LOL. Mempilot does have a point there. In otherwords have a large enough tank so that you can stay down long enough.

More importantly though when you are starting off is to relax, try not to kick to fast and do your best to keep your SAC rate down. As you become better at your buoyancy control you will find that you will use a lot less air for your BCD. Also make sure you aren't overweighted. All of these factors will help out so you won't have to manually inflate your bcd. Sure it's a good exercise and not one that you should be unfamiliar with doing.

 

[matt_unique]

When I need to adjust my buoyancy by adding air, I do it manually in an effort to try and save tank air. My wife tells me I am actually wasting air doing it that way. Since I am seldom right (life is easier that way), I was wondering if anyone has an opinion on this topic.

The air you would use is just about negligible. If you are constantly dumping and adding air then it would be noticeable but short of that you don't need to worry about it. You will use less air as you gain experience.

--Matt

 

[mempilot]

Just to show a quick analagy.

A 6cf bottle is enough to inflate a drysuit for several dives. I doubt you're using very much backgas to inflate your bc unless you are overweighted.

If you are an exceptionally dense person(no harm meant, talking mass here), then try a 100cf tank instead of the traditional 80's.