How much air in your BC?

[Walter]

OK, this was fascinating. So let me get this straight, the advantages then of ST cylinders over AL is NOT that you get less buoyancy swing from full to empty but just that the cylinders do not become positively buoyant when empty?

Almost. What you are missing is the steel tank is lighter and you're carrying less lead. That means you have less work to do.

 

[spectrum]

Deefstes

Read this and follow the math. It illustrates what's happening.

The effects of air depletion are a wash between cylinder materials or styles. The advantages center around weight and buoyancy properties.

Pete

 

[SharkDiver36]

Most of what I've read is great advice to your questions; I didn't read every response tho.

The #1 and #2 rule in diving is - Comfort & Fit.

I guess it boils down to what you're comfortable with. Knowing your configuration helps with this; steel vs. AL.

My preference, as well as some of the response's I've read, is to be a little heavy by a couple pounds. Being a couple pounds heavy really doesn't have an impact on air consumption either, one extra squirt of air in your bc isn't a crisis worth arguing over.

When I let the air out I go down easy. When I do my safety stop I don't have to ever worry about being a little 'light' and fight to stay at a shallow depth.

Be comfortable. Use the weight you like and know how much you need if you dive steel tanks or AL tanks. That really is the bottom line.

You should be comfortable with your gear.

 

[Doc Harry]

There was a time when people went scuba diving without a BC.

 

[D_B]

If your properly weighted, then you will never ... "be a little heavy by a couple pounds."
and will never ... "have to ever worry about being a little 'light' and fight to stay at a shallow depth."

I'm sure there are occasions when carrying a couple of extra lbs would be necessary, but I could feel when I carried 2lbs by accident and I didn't like what it did to my buoyancy control and my comfort underwater

 

[shark_tamer]

Here's my 0.02$.

And feel free to correct me if this is totally wrong.

At the beginning of the dive, I want to barely be able to break the surface.
Then add 1 kg.

That's how I have learned it.

 

[Nemrod]

None to a puff or two.

N

 

[LeadTurn_SD]

None to a puff or two.

N

1+

I dive single tank (Al80), 3mm full wetsuit plus 5mm hood.

I generally do not use any air in my wing until I get below about 50 feet, and even there it is fairly optional (can still hover easily enough using lung volume). This would be different with a thicker wetsuit of course.... I have the advantage of a 3mm wetsuit and some, ahem, "bioprene" that does not lose it's buoyancy

Best wishes.

 

[Hatul]

Another point relevant to this discussion is that it's more efficient to dump air from the inflator hose pointing up than from all the dump valves on the bladder, especially if the BC is prone to air trapping.

Adam

 

[TSandM]

it's more efficient to dump air from the inflator hose pointing up

I'm actually fairly sure that I can dump faster from my rear dump than from my inflator hose, and in fact, tech divers are often taught that, in the face of a runaway inflator, the rear dump should be used for that reason.