SAC decreasing with depth

[petmal]

Hello.

I used Suunto DM to calculate SAC as a function of time for some of my dives. What I found is that my SAC consistently decreases with increasing depth. The effect may be pretty substantial. Does anybody have the same experience?
I was thinking about effects of nitrogen narcosis (although the effect is present even in shallow dives, like 15m or so) and increased gas density, which as far as I know has also impacts on breathing.

Petr

 

[spectrum]

In recreatiuonal ranges work of breathing should not be a factor assuming gear is in good repair. Anxiety, percieved or not is more likely.

When diving at depth how did you feel? Were you in your comfort zone?

Pete

 

[String]

At depth buoyancy is easier, dont need to vary lungs or BC as much. You aren't "working" as hard as you are during an ascent or descent and so on.

My SAC on technical dives is lower for the bottom portion than the deco, especially the shallower deco where buoyancy is more fiddly.

 

[pjhansman]

Hello.

What I found is that my SAC consistently decreases with increasing depth. The effect may be pretty substantial.

Perfect.....I think that means if you go deep enough you won't have to breathe at all

 

[petmal]

In recreatiuonal ranges work of breathing should not be a factor assuming gear is in good repair. Anxiety, percieved or not is more likely.

When diving at depth how did you feel? Were you in your comfort zone?

Pete

I was fine, swimming at very much the same rate all the time. I understand it is often more work on ascends and descends, but I don't think this can explain everything.

 

[petmal]

Perfect.....I think that means if you go deep enough you won't have to breathe at all

No doubt about it... SAC could even get negative, than I would be producing gas rather than consuming it.

 

[spectrum]

Oh I misread your OP. You are running a lower SAC at depth, a favorable situation. (That's not a common concern)

This is really good news. Think about it.... In each breath you have multiple atmospheres of air and the requisite oxygen. You have more O2 in your lungs than you can hope to use. If you have sucessfully coupled that with a good clean breathing style and good diving form you may notice that your frequency of breathing becomes almost alarmingly low. You may be in the gooove so to speak.

Pete

 

[Cave Diver]

I would be producing gas rather than consuming it.

Some people do that enough already on the surface.

 

[petmal]

In recreatiuonal ranges work of breathing should not be a factor assuming gear is in good repair.

I am not entirely sure about this but I remember reading about effects of increased gas density on breathing. I think it actually slows one's breathing down and it has nothing to do with the regulator. It is more a physiological effect.

 

[petmal]

Oh I misread your OP. You are running a lower SAC at depth, a favorable situation. (That's not a common concern)

This is really good news. Think about it.... In each breath you have multiple atmospheres of air and the requisite oxygen. You have more O2 in your lungs than you can hope to use. If you have sucessfully coupled that with a good clean breathing style and good diving form you may notice that your frequency of breathing becomes almost alarmingly low. You may be in the gooove so to speak.

Pete

As far as I know blood saturation with O2 is nearly 100% even in 1 ATA of pressure. Could increased ppO2 make body cells more effective? I have no idea...