Handling Hypoxic Bailouts with a BOV

Capt Morgan said:
I have my BOV connected by an QC6 to one mix and that's my bottom mix. The bottom mix like all my BO cylinders has a second stage fitted, my thinking is that the BOV is only for the initial bail out and will soon be switched to the second stage. I wouldn't trust myself to be unplugging and plugging QC6's while holding my breath so don't see the point of having more than one cylinder connected. I like to keep things simple.
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As an update to this discussion, I have now changed to Morgans setup as it is way more simpler and safer, just a QC6 on the deep bailout, if I make it as far as 20M it should be no problem to stick a 2nd stage in my mouth.
 
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A wreck dive is obviously different then a cave dive in regards to how long you may be off board. For deep wrecks I use a mix that's breathable at all depths. If I run my PO2 hot on the bottom I accept that knowing I'm leaving the bottom real fast. For example I run a 15/50 off-board mix at 300' which is a 1.51. I don't think that's too rich for the depth, especially if your leaving the bottom quickly. As far as this mix being hypoxic at or very near the surface? Most training agencies would say it is, but why is it different then breathing air at 9,000'? It's the same PO2. I have breathed at 10,000' hiking with only a few hours of acclimation, and 14,400' (12.2 PO2) starting 24 hours earlier at near sea level. This being exhausting hiking with a pack going uphill at a high angle. So am I wrong to think I can huff and puff at altitude with a low PO2 and pass out at the surface (or ladder) with an identical PO2. For me I feel comfortable with it and I like having a big bottle of all depth breathable mix plumbed to my BOV.
 
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Gotta ad... I feel comfortable with it. Running a 1.5, particularly in a mixed gas, is hazardous and the clock is ticking. I do it knowing that if I bailout I'm leaving the bottom quickly.
 
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hbm said:
A wreck dive is obviously different then a cave dive in regards to how long you may be off board. For deep wrecks I use a mix that's breathable at all depths. If I run my PO2 hot on the bottom I accept that knowing I'm leaving the bottom real fast. For example I run a 15/50 off-board mix at 300' which is a 1.51. I don't think that's too rich for the depth, especially if your leaving the bottom quickly. As far as this mix being hypoxic at or very near the surface? Most training agencies would say it is, but why is it different then breathing air at 9,000'? It's the same PO2. I have breathed at 10,000' hiking with only a few hours of acclimation, and 14,400' (12.2 PO2) starting 24 hours earlier at near sea level. This being exhausting hiking with a pack going uphill at a high angle. So am I wrong to think I can huff and puff at altitude with a low PO2 and pass out at the surface (or ladder) with an identical PO2. For me I feel comfortable with it and I like having a big bottle of all depth breathable mix plumbed to my BOV.
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hbm said:
A wreck dive is obviously different then a cave dive in regards to how long you may be off board. For deep wrecks I use a mix that's breathable at all depths. If I run my PO2 hot on the bottom I accept that knowing I'm leaving the bottom real fast. For example I run a 15/50 off-board mix at 300' which is a 1.51. I don't think that's too rich for the depth, especially if your leaving the bottom quickly. As far as this mix being hypoxic at or very near the surface? Most training agencies would say it is, but why is it different then breathing air at 9,000'? It's the same PO2. I have breathed at 10,000' hiking with only a few hours of acclimation, and 14,400' (12.2 PO2) starting 24 hours earlier at near sea level. This being exhausting hiking with a pack going uphill at a high angle. So am I wrong to think I can huff and puff at altitude with a low PO2 and pass out at the surface (or ladder) with an identical PO2. For me I feel comfortable with it and I like having a big bottle of all depth breathable mix plumbed to my BOV.
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Couldn't disagree more with this - sorry.

Racing off the bottom in a bailout situation - good luck! Can you not imagine any situation where you might be delayed? Also, maybe if you dive deeper than 90m you would eventually reach a point where your strategy breaks (for me its already broken at around 70m)

Hypoxia is a risk for sure - but don't rob Peter to pay Paul.
 
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hbm said:
A wreck dive is obviously different then a cave dive in regards to how long you may be off board. For deep wrecks I use a mix that's breathable at all depths. If I run my PO2 hot on the bottom I accept that knowing I'm leaving the bottom real fast. For example I run a 15/50 off-board mix at 300' which is a 1.51. I don't think that's too rich for the depth, especially if your leaving the bottom quickly. As far as this mix being hypoxic at or very near the surface? Most training agencies would say it is, but why is it different then breathing air at 9,000'? It's the same PO2. I have breathed at 10,000' hiking with only a few hours of acclimation, and 14,400' (12.2 PO2) starting 24 hours earlier at near sea level. This being exhausting hiking with a pack going uphill at a high angle. So am I wrong to think I can huff and puff at altitude with a low PO2 and pass out at the surface (or ladder) with an identical PO2. For me I feel comfortable with it and I like having a big bottle of all depth breathable mix plumbed to my BOV.
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It's not (just) the ppO2, BO with only 50% helium is too dense for 300ft. 50% helium surpasses the recommended density of 5.2gm/L at 7 ATA or 200ft. At 10 ATA its a whopping 7.42 gm/L. The 15% O2 is your choice, but you might want to bump that helium fraction up to 65+% to get the density down in line with recommended thresholds.
 
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