Buoyancy Control with Dry Suit

[MXGratefulDiver]

I'm confused, once you achieve neutral buoyancy, BCD's or drysuits shouldn't need to be adjusted until the end of the dive. (Except for the drysuit comfort adjustment).
I teach that once neutral buoyancy is established, very slight adjustments may or may not be needed in order to counteract the air put into the drysuit. But I don't encourage drysuit as a buoyancy device. Jonnythan hit the nail on the head IMO.

Hmmm ... this would only be true on a square profile dive. Otherwise, as you change depth, the air in your suit and/or BCD will compress while the weight it is compensating for will not ... therefore you will need to add air as you go deeper or vent it as you go shallower to maintain neutral buoyancy.

... Bob (Grateful Diver)

 

[ScubaFreak]

Hmmm ... this would only be true on a square profile dive. Otherwise, as you change depth, the air in your suit and/or BCD will compress while the weight it is compensating for will not ... therefore you will need to add air as you go deeper or vent it as you go shallower to maintain neutral buoyancy.

... Bob (Grateful Diver)

hey bob,

That's true I guess, i was going on the basis of achieving your desired depth and then achievng your neutral buoyancy.

SF

 

[jonnythan]

Hmmm ... this would only be true on a square profile dive. Otherwise, as you change depth, the air in your suit and/or BCD will compress while the weight it is compensating for will not ... therefore you will need to add air as you go deeper or vent it as you go shallower to maintain neutral buoyancy.

... Bob (Grateful Diver)

It's not even true on a square profile dive. You'll need to dump a small amount of air as time goes on to counteract the buoyancy you're gaining by breathing down your gas.. especially if you're diving with lots of back gas.

At the beginning of the dive, you'll have to have enough air in either your wing or suit to counteract the weight of the gas compressed into your tank(s).. and you need to give that up slowly over the course of the dive. That's why you weight yourself with empty tanks.. you start out "extra" negative by the weight of your gas.

 

[ScubaFreak]

i wear steel tanks, don't have that big of an effect on my buoyancy.

 

[MXGratefulDiver]

It's not even true on a square profile dive. You'll need to dump a small amount of air as time goes on to counteract the buoyancy you're gaining by breathing down your gas.. especially if you're diving with lots of back gas.

Over time this is true ... but normally the rate of change due to cylinder boyancy as you breathe down your gas is minimal compared to that induced by depth changes as you move about on your dive. Also, keep in mind that slight changes ... over a period of, say, a couple of minutes ... will be compensated for by your breathing pattern.

Of course, all of this is dependent on your breathing habits and your depth profile, both of which tend to vary with time and conditions.

But in general, yes ... it's a given that your cylinders will become more buoyant as you breathe down your gas.

... Bob (Grateful Diver)

 

[Al Mialkovsky]

I used to use the drysuit for bouyancy but now I put just enough gas in there to stay comfortable.

 

[boomx5]

I would be curious to find out how many people use their suit for bouyancy control, while wearing steel doubles filled with Trimix and carrying a couple of deco bottles. I would also be interested to see what size argon bottle they use.

 

[MXGratefulDiver]

I would be curious to find out how many people use their suit for bouyancy control, while wearing steel doubles filled with Trimix and carrying a couple of deco bottles. I would also be interested to see what size argon bottle they use.

In general, it would be interesting ... however, given that this thread is in the New 2 Scuba forum, I'd hazard to say not many ...

... Bob (Grateful Diver)

 

[boomx5]

In general, it would be interesting ... however, given that this thread is in the New 2 Scuba forum, I'd hazard to say not many ...

... Bob (Grateful Diver)

Yeah...I know what forum it's in...I was just curious that's all.

 

[JasonH20]

I have a feeling this probably becomes a second nature kind of thing after awhile. Add air to suit / bc, either / or, it won't matter, you can handle and adjust just fine either way after you get comfortable with it.

I can remember when I was 15 and learning to drive a stick. Modulating the clutch took my full concentration to keep from stalling the car. Now I drive rush hour traffic with a 6sp manual without a second though. Give me 50 dives, and I'll probably wonder why I ever struggled with buoyancy...

As everyone says, practice, practice, practice! (which I hope to do alot of now!)

Thanks,
Jason