Virginian diver dead at 190 feet - Roaring River State Park, Missouri

[tursiops]

Found what I was remembering. It was more than a hint and occurred back in the summer. Hopefully this links back to his full posting.

Assuming O2 is as narcotic as N2 is meant to be a conservative, safe assumption, not a statement of scientific fact.

 

[L13]

Found what I was remembering. It was more than a hint and occurred back in the summer. Hopefully this links back to his full posting.

Didn't link. I would like to read the original post, could you try and link it again?

 

[inquis]

Didn't link.

It works, click on his name or the circled up-arrow in the quote header.

 

[L13]

It works, click on his name or the circled up-arrow in the quote header.

Thanks! I didn't know it worked that way!

I don't know how I missed that thread. Great info!

 

[boriss]

The American way of describing tanks makes things blurry.
Does it help if they are called 7L tanks instead of 50s?
They were most likely filled to 3600-3900 making them 70 some CF. Pretty similar volume to an AL80 which is a standard deep BO for that depth range.

A bit unrelated to the thread, but I've seen this mentioned several times and it's inaccurate. At 3600psi the LP50's contain ~63.6 cf. An AL80 at 3k psi will hold ~77.5 cf. That's about a 20% difference. Just something to keep it in mind for when you're planning.

 

[Whitrzac]

A bit unrelated to the thread, but I've seen this mentioned several times and it's inaccurate. At 3600psi the LP50's contain ~63.6 cf. An AL80 at 3k psi will hold ~77.5 cf. That's about a 20% difference. Just something to keep it in mind for when you're planning.

Math works out to 68cf at 3600psi and 73cf at 3900.
There is some loss from z factor, I dont have that ## handy.
Most people are hesitant to fill al80s above 3k, most of them I've seen are slightly less.

There's something to be said about the significantly lower drag too.

Ether way, its a moot point on this dive. There were stage bottles every 50(?) ft at RR.

 

[Manatee Diver]

Ether way, its a moot point on this dive. There were stage bottles every 50(?) ft at RR.

Agreed, while I don't agree with the team's choices of tanks and contents, it wasn't a factor in the death as the general understanding from the team members that have spoken up that he should've had trimix for this dive.

 

[boriss]

Math works out to 68cf at 3600psi and 73cf at 3900.
There is some loss from z factor, I dont have that ## handy.
Most people are hesitant to fill al80s above 3k, most of them I've seen are slightly less.

There's something to be said about the significantly lower drag too.

Ether way, its a moot point on this dive. There were stage bottles every 50(?) ft at RR.

"Math" (based on extrapolation) is incorrect, which is why I made my post. Here are the z factors, for reference: Z Factors for SCUBA | Dive Gear Express®

The number I gave (63.6cf @ 3.6k) is for air. If I calculated for trimix that number would be about 10% lower, but the quantity of gas wasn't the only important point, it's also the relative difference comparing to AL80.

Lastly, it's a moot point as far as the dive is concerned, which is why I was responding to Tracy. I wanted to ensure that he (or anyone else who may read it) use correct numbers for planning purposes. If there's anything we've learned from this incident and so many others is that human factors play a major role in catastrophes. That starts with planning. I'm only trying to ensure that people are planning correctly instead of assuming their LP50 doubles might contain 140cf of gas when overfilled - they do not. That's all... nothing more nothing less.

Back to regularly scheduled programming

 

[Tracy]

"Math" (based on extrapolation) is incorrect, which is why I made my post. Here are the z factors, for reference: Z Factors for SCUBA | Dive Gear Express®

The number I gave (63.6cf @ 3.6k) is for air. If I calculated for trimix that number would be about 10% lower, but the quantity of gas wasn't the only important point, it's also the relative difference comparing to AL80.

Lastly, it's a moot point as far as the dive is concerned, which is why I was responding to Tracy. I wanted to ensure that he (or anyone else who may read it) use correct numbers for planning purposes. If there's anything we've learned from this incident and so many others is that human factors play a major role in catastrophes. That starts with planning. I'm only trying to ensure that people are planning correctly instead of assuming their LP50 doubles might contain 140cf of gas when overfilled - they do not. That's all... nothing more nothing less.

Back to regularly scheduled programming

I am mildly familiar with gas planning. Double 50s at 140cf are adequate bailout for me on a 200' dive with a straight exit. I am not familiar with the cave they were diving and I don't know the exit path. The difference between those at 140 cf and double 80s at 154 is marginal in my opinion. If I am planning bailout and 14 cf is the difference between planned and required, I change my plan.

 

[Sebs]

I've read this thread start to finish. I'm still a rec diver but have taken intro to tech (and was told to dive more doubles) and even with my extremely limited understanding of tech diving, at some point the conversation of "hey, what gas are you using and what's your p02" should have been had. My instructor was teaching ITT with a heavy influence of GUE so maybe that's not normal but to me it's incredible that you have an expedition team that somehow failed to see that one of its divers was using a gas woefully inadequate for the job.

Hell, even in rec diving you're meant to ask your dive buddy what they're diving so you have somewhat similar NDL and MOD.

Honestly that expedition team leader should be ashamed of themselves for running such a dive operation.