Retained Stage Breathing Order...

[Manatee Diver]

Back to stage cave diving. That is above my level of expertise but sounds like a CCR is needed if that many stages are needed…

It would make dive planning easier. But I don't quite feel ready for CCR yet.

 

[rddvet]

It would make dive planning easier.

That is a misconception, just like you can carry less gas due to being cc. They seem to be the most commonly perpetuated myths along with "you get less deco cc". The benefit imo is added time and safety. Things can definitely go wrong on the ccr, but most of the time there are warning signs, it doesn't usually happen as a sudden kaboom, you have more time to fix them, and you have more options to fix a problem such as scr mode. The real benefit is I can see 5 times more parts of ginnie with a stage on cc than I can on oc because I figure out my radius of getting back to the surface and can then explore wherever the hell I want within that area. If say for example I plan to go past the henkel, I've still got to carry two stages like I would on oc.

 

[Manatee Diver]

The real benefit is I can see 5 times more parts of ginnie with a stage on cc than I can on oc because I figure out my radius of getting back to the surface and can then explore wherever the hell I want within that area.

That is pretty much what I mean, my understanding is that CCR gas planning is basically a chain on a dog. Two LP85s would be X,000ft from the entrance, stage is another Y,000ft.

So planning this circuit would be more looking at my maximum penetration and working from there.

 

[J-Vo]

I was not aware until this thread that this was controversial, just that some don't do it rite.

I was taught to breath half+200 from each stage then drop it while adding half breathable to back gas reserve. So, for each full 80 stage, you need to increase your back gas reserve about 36cuft. Whenever you have a stage on you, you should be breathing it and reserving as much back gas as possible for emergencies. Unless of course your at drop pressure and waiting for a good spot to drop it.

This increases turn pressure on a set of 85s by about 200psi per stage. So, turn at 2600 when starting with 3600 and a full stage. Turn at 2800 of back gas on a two stage dive. 6 stages and your back gas 85s are all reserve.

 

[oya]

Without getting into math...

If I'm wearing a stage, I'm breathing a stage.

For you example of a circuit: Why not just breath the stage to near-dead and retain donatable backgas as emergency gas (with the built-in safety buffer of retained gas but, as I said, I'm not gonna get into math.

But as other have pointed out, there's a million different ways of doing or teaching it. And, also pointed out, just depressingly it seems the most common is either "just breath thirds" or 1/2+ without a backgas reserve.

 

[tbone1004]

I was not aware until this thread that this was controversial, just that some don't do it rite.

I was taught to breath half+200 from each stage then drop it while adding half breathable to back gas reserve. So, for each full 80 stage, you need to increase your back gas reserve about 36cuft. Whenever you have a stage on you, you should be breathing it and reserving as much back gas as possible for emergencies. Unless of course your at drop pressure and waiting for a good spot to drop it.

This increases turn pressure on a set of 85s by about 200psi per stage. So, turn at 2600 when starting with 3600 and a full stage. Turn at 2800 of back gas on a two stage dive. 6 stages and your back gas 85s are all reserve.

You're going to want to redo your math... It's a LOT more than 200psi per stage....

36cf*2640/85=1100psi. On doubles/sidemount divide by half so 600psi per stage....

Without getting into math...

If I'm wearing a stage, I'm breathing a stage.

For you example of a circuit: Why not just breath the stage to near-dead and retain donatable backgas as emergency gas (with the built-in safety buffer of retained gas but, as I said, I'm not gonna get into math.

But as other have pointed out, there's a million different ways of doing or teaching it. And, also pointed out, just depressingly it seems the most common is either "just breath thirds" or 1/2+ without a backgas reserve.

I'm with you. I breathe the stage to a third, carry it twice as far as I breathed it in minutes, then breathe the stages until the Jetstreams keep bubbling a bit when I stop inhaling signaling they are at 200psi ish and then switch to the next stage. Way better IMO.

I do take @Bobby 's advice seriously though and if I'm diving stages to thirds I make sure to carry them farther in than I breathed them. No downside other than slight inconvenience to keep carrying them in but huge benefits if you are in an emergency to having more gas farther back in the cave. Obviously in the example of breathed a stage to 600ft and stage rock as it 900ft with no-mans land at between it and the next stage rock at 1500ft then drop it at 900, but don't drop them the second you hit thirds.

 

[kaylee_ann]

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[kensuf]

You're going to want to redo your math... It's a LOT more than 200psi per stage....

36cf*2640/85=1100psi. On doubles/sidemount divide by half so 600psi per stage....

Which works out to 200 off the penetration gas, 200 off the exit gas, leaving you an extra 200 in reserve too.

 

[tbone1004]

Which works out to 200 off the penetration gas, 200 off the exit gas, leaving you an extra 200 in reserve too.

ahh, when he said it increases turn pressure by 200psi I read that as instead of turn at 2400 you would turn at 2600 when in reality you now turn at 3000.

 

[kensuf]

No, you turn at 2600.

Straight thirds:
Start at 3600 (1200/1200/1200)
Turn at 2400 (1200)
Exit using 1200 (leaving with 1200)
Final reserve 1200

Shaving 200 off penetration gas
Start at 3600 (1000/1000/1600)
Turn at 2600 (1000)
Exit using 1000 (leaving with 1600)
Final reserve 1600