Current Views on Hypoxic bailout/BOV Configurations

[Tracy]

It's quite a conundrum. I can't argue with what you've just said, yet I have stayed with a necklaced bailout second stage.

My (?flawed?) reasoning this far has been
1) if I plumb it to my 3l, I've got very little time
2) I've got extra weight and hoses and connections right where I don't want them
3) I've gotta plan how to plumb my extra bottles to plug in soon after the stress of my bailout

Yet... how nice to just flick a switch in an emergency.

To continue the train of justifying a decision that many disagree with, I've also convinced myself I won't get into that situation without  early warning.
Because I realized that (its shortcomings aside), it was an extremely fast solution to a big problem, if I were to consciously reject a BOV, how was I going to recognize a hit? Dr. Simon Mitchell teaches us that fully 25% of divers don't sense their hypercarbia.
So I did this:
Post in thread 'Overshooting NDL and mandatory deco stops' Overshooting NDL and mandatory deco stops

And that's how I justified keeping my simple necklace...

But I think I'm going to try it one more time. I think next time I'll push it as high as I can, and then, instead of just pulling out the mouthpiece and sighing nice, clean air, I'll see if I can hold my breath long enough to purge and place the mouthpiece of a bailout bottle. I've repeatedly read of folks that say they couldn't bear to stop breathing long enough to switch. I think it's a psychological phenomenon (since my O2 sat should be fine at depth), but practicing it can't hurt should I let it go so long before bailout that I'm really panicking.
Or maybe it'll prove that I  have to recognize it early enough to be able to switch. Or maybe it'll prove that I should buy that 12-pound BOV...

As a small note. While true, a BOV is heavy on land. My IBOV is neutral in the water. It is also plumbed to my bailout. Once I bail to the BOV, I never come off it. Through the ascent and gas switches. In the even of a caustic, yes, I would deploy a reg, but that would be the only reason.

 

[Wibble]

I’ve now been won around to using a BOV on my Revo. Just waiting for budgetary approval from SWMBO…

Will shortly be ordering a Revo BOV plus loop hoses to keep the DSV and hoses as a backup.

My planned usage profile would be:

• Will not connect BOV to diluent cylinder
• BOV will always be connected to the bottom gas bailout using QC6 connectors
• Always have "BCD" tails and regulators on all bailout & deco cylinders (as per currently)
• Basically the BOV is only for bailing out to deep bailout gas. Deco switches will be as per normal regulator switch.
• In the event of a shallow CO2 hit, will switch from CC to OC BOV, wait for breathing to settle then switch to the appropriate decompression cylinder.

Thinking is this is simple with as little change as possible. I am not planning on doing any "hypo" hypoxic 100m/330ft plus depths so bailing out to bottom bailout will be normoxic-ish at all depths, certainly OK at 6m/20ft — if I ever do, then may change this.


Any thoughts/comments on this logic?

 

[rsingler]

Any thoughts/comments on this logic?

Reassure me that your BOV has a low enough WOB that I can recover from a CO2 hit when I'm hyperventilating more than I ever have before, and with thick gas.

 

[Tracy]

Reassure me that your BOV has a low enough WOB that I can recover from a CO2 hit when I'm hyperventilating more than I ever have before, and with thick gas.

I can assure you mine does. The IBOV is an apeks xtx50. It breathes better than my old detuned bailout regs.

 

[JonG1]

Sounds good Wibs and makes perfect sense to me.

 

[KenGordon]

I’ve now been won around to using a BOV on my Revo. Just waiting for budgetary approval from SWMBO…

Will shortly be ordering a Revo BOV plus loop hoses to keep the DSV and hoses as a backup.

My planned usage profile would be:

• Will not connect BOV to diluent cylinder
• BOV will always be connected to the bottom gas bailout using QC6 connectors
• Always have "BCD" tails and regulators on all bailout & deco cylinders (as per currently)
• Basically the BOV is only for bailing out to deep bailout gas. Deco switches will be as per normal regulator switch.
• In the event of a shallow CO2 hit, will switch from CC to OC BOV, wait for breathing to settle then switch to the appropriate decompression cylinder.

Thinking is this is simple with as little change as possible. I am not planning on doing any "hypo" hypoxic 100m/330ft plus depths so bailing out to bottom bailout will be normoxic-ish at all depths, certainly OK at 6m/20ft — if I ever do, then may change this.


Any thoughts/comments on this logic?

This is my setup.

I assume that any problem with co2 making a switch hard will improve after I have breathed down the deep bailout.

Having multiple gas sources for the BOV seems to me to contradict all the normal rules for identifying and verifying a gas prior to switch. Also there is a risk that the BOV starts off on the wrong gas.

 

[Wibble]

Reassure me that your BOV has a low enough WOB that I can recover from a CO2 hit when I'm hyperventilating more than I ever have before, and with thick gas.

Apparently the Revo BOV WOB is good according to those that have used one. It’s also light and compact.

 

[Tracy]

Having multiple gas sources for the BOV seems to me to contradict all the normal rules for identifying and verifying a gas prior to switch. Also there is a risk that the BOV starts off on the wrong gas.

How? I don’t follow this at all? The procedure for a gas switch didn’t change.

 

[Wibble]

How? I don’t follow this at all? The procedure for a gas switch didn’t change.

My logic for only connecting to the bailout (normoxic and above) is that there cannot be any question of it being a non-breathable gas at any depth (ignore very hypoxic mixes -- out of scope)

I appreciate that you could build in a check to ensure you're breathing from a breathable gas before switching to the BOV. IMHO that adds a step which both complicates the process (flick BOV lever) and delays getting to breathable gas -- the primary reason for using a BOV and not a regulator.

Of course for very deep dives you'd probably be changing the BOV gas as you descend/ascend as the hypoxic mixes would be fatal in the shallows and intermediate/deco mixes are poisonous at depth. (Is this what you mean?)



For now I want a very simple solution: bottom bailout and a quick flick of the BOV lever. Then standard OC protocols for no-tox deco gas switching using their regulators.

 

[lermontov]

My logic for only connecting to the bailout (normoxic and above) is that there cannot be any question of it being a non-breathable gas at any depth (ignore very hypoxic mixes -- out of scope)

I appreciate that you could build in a check to ensure you're breathing from a breathable gas before switching to the BOV. IMHO that adds a step which both complicates the process (flick BOV lever) and delays getting to breathable gas -- the primary reason for using a BOV and not a regulator.

Of course for very deep dives you'd probably be changing the BOV gas as you descend/ascend as the hypoxic mixes would be fatal in the shallows and intermediate/deco mixes are poisonous at depth. (Is this what you mean?)



For now I want a very simple solution: bottom bailout and a quick flick of the BOV lever. Then standard OC protocols for no-tox deco gas switching using their regulators.

I agree with @Tracy -surely one would do a check on the surface as to what gas your BOV is plumbed into even with a say 10/70 mix your ok at 10m, its extremely unlikely youll get a co2 hit on a descent before you reach a safe po2 so were only talking about ascent issues . Obviously if your ascending you may need to switch to a better gas but those protocols are already in place