Controlling Buoyancy with your breath: Why?

[Boyan]

Hi,

I recently finished GUE Fundamentals. One of the less intuitive lessons we learned was about weights, and specifically how we have too much of those.

The result of few weights seems to be a bigger impact of breathing on buoyancy.

At the end I got the hang of it, and I see some advantages, but I also see some disadvantages. When I did my OW cert dives I felt completely stable. It wouldn't matter if I took very deep and slow breaths, I wouldn't move a centimeter in the water column at all. With the DIR setup when I take a deep breath followed by a slow and complete empty lung I go up and down extremely.

Why would this be an advantage or am I doing something wrong?

Imagine: You are in a cave, something happens, you take a big breath, shoot to the top of the cave etc. Seems like an unnecessary potential problem which could be easily fixed with more weights + more air in the BC, which would diminish the effect of the lung on buoyancy.

 

[RyanT]

Alternatively, not being overweighted gives you enormous control of your position in the water column. So in your example of the cave, imagine you need to rise a foot or drop a foot to get around an obstacle. You can easily do this by taking a deeper or shallower breath. If you are heavy and unable to control your depth with your breathing, then you have to resort to kicking and/or lots of small buoyancy adjustments. Using your breathing to make small adjustments to your depth is much easier than other methods.

 

[fmerkel]

Try following your own logic to the other extreme > lots of weight and a huge BCD full of air = very stable clumsy mass underwater.

 

[Boyan]

Try following your own logic to the other extreme > lots of weight and a huge BCD full of air = very stable unmovable mass underwater.

Sure, that's a problem too.

 

[oly5050user]

What do you do if you make an out of air ascent and need to orally inflate your bcd? Too much lead and you may find yourself sinking while orally inflating bcd..you should be able to inflate bcd with face in water and not sinking or even needing to exert any energy to stay afloat. Two breaths into bcd should be enough to easily float. More than 3 or 4 breaths you are overweighted.

 

[The Chairman]

You are in a cave, something happens, you take a big breath,

Why take a deep breath in the first place? That's like complaining that if you turn the wheel of your car hard you're going to turn. What's the point of having precise control if you're going to freak out and lose it? The point is to be in control at all times... even if crap happens. Always establish neutral buoyancy before you try to solve a problem.

My OW students won't get certified by me if they aren't able to control their depth with their breath. In fact, they have to be able to descend to the bottom of the pool, ascend to the top and then descend to the bottom again using only their breathing. No control? No cert.

 

[Boyan]

What do you do if you make an out of air ascent and need to orally inflate your bcd? Too much lead and you may find yourself sinking while orally inflating bcd..you should be able to inflate bcd with face in water and not sinking or even needing to exert any energy to stay afloat. Two breaths into bcd should be enough to easily float. More than 3 or 4 breaths you are overweighted.

In a situation like this I suppose you would swim up or drop your weights.

 

[Boyan]

Why take a deep breath in the first place? That's like complaining that if you turn the wheel hard you're going to turn. What's the point of having precise control if you're going to freak out and lose it? The point is to be in control at all times... even if crap happens. Always establish neutral buoyancy before you try to solve a problem.

My OW students won't get certified by me if they aren't able to control their depth with their breath. In fact, they have to be able to descend to the bottom of the pool, ascend to the top and then descend to the bottom again using only their breathing. No control? No cert.

For some reason we were thought to take long deep breaths when diving, not sure where this comes from but I have heard it from two different OW instructors.

 

[diver0008]

For some reason we were thought to take long deep breaths when diving

A wrong reason.

Using your breath to get within inches of something and stay there takes many dives to master.

Breathing deeply underwater will waste your gas, and if your are properly weighted, render you somewhat out of control.

By choosing when to use large or small inhales/exhales you can fine tune your positioning.

But you have to have your weighting and neutrality figured out first.

 

[JohnN]

Why take a deep breath in the first place? That's like complaining that if you turn the wheel of your car hard you're going to turn. What's the point of having precise control if you're going to freak out and lose it? The point is to be in control at all times... even if crap happens. Always establish neutral buoyancy before you try to solve a problem.

My OW students won't get certified by me if they aren't able to control their depth with their breath. In fact, they have to be able to descend to the bottom of the pool, ascend to the top and then descend to the bottom again using only their breathing. No control? No cert.

Isn't it one of the balancing acts. . too much shallow breathing will build up CO2 and lead to hypercapnia. Too much deep breathing and you become an aqueous yo-yo.