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

[Nitrogenius]

They likely started out as 32% fills from a cave country trip and were topped with air a few times.

Maybe.. then I would account for them as what they are analyzed for MOD but otherwise treat them like air for decompression purposes. Meaning not really a decompression gas, but mere "deep BO" only and not a particular good one.

50s were more than enough gas, I believe it was mentioned that they were at most 50ft from the next stage bottle. One of the news articles mentioned 10-14 stages.

Well only if the usage of those stage tanks was actually planned for and the individual diver capable in the handling.
To all info that is available here that seems somewhat questionable also given the course of events leading to the accident per the report does not suggest that the support divers have in fact been relying on any of the staged tanks for BO purposes..
It seems that alls those staged tanks were intended for the push divers only.
of course a well rrained diver could have made use of them in an emergency but it seems to be a fact that they have not even been attempted to be used.

The American way of describing tanks makes things blurry.
Does it help if they are called 7L tanks instead of 50s?

nope i am very well aware what it means so not blurry to me at all

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.

Understood that they might have been "cave filled"..
They would not even be an 80 and in my book and also as best practices at least (if not good practices) suggest on a decompression dive to such depth also a single 80 is not enough..
In fact any "single" gas BO is not reasonable at such dive in my opinion and seems like an "alpinist" approach.
Only the incorporation of the stages could change that. But that seems questionable if that had been planned for (see above)

 

[Nitrogenius]

You're not looking at how standard gases fit into the overall safety system, how they can be used to remove pressure from the divers to do the dive without the right gases, and how they can enable other members of the group to speak up when they see something they view as unsafe happening.

By choosing to dive standardized gasses the team is agreeing before the "heat of the moment" on what is ....

If he'd had been diving standardized gasses and using a team approach to diving the conversation on the pre-dive checks could have gone something like this.

• The gas selection parameters are chosen beforehand, not when you're dealing with logistical or cost issues and avoids debates around acceptable risk once people have already invested considerable time and money and feel external pressures to complete the dive

Interesting views to be honest..
Never looked at standard gases from this angle.
Never been a fan of them as I am a very much use your own brain approach guy as that's the reason you have it and my personal believe that standardization leads to stupidity on the long run as the mainboard is not really being challanged anymore, however this is an appealing view!!
Thanks for that.
Something to THINK about

 

[PirateFoxy]

Interesting views to be honest..
Never looked at standard gases from this angle.
Never been a fan of them as I am a very much use your own brain approach guy as that's the reason you have it and my personal believe that standardization leads to stupidity on the long run as the mainboard is not really being challanged anymore, however this is an appealing view!!
Thanks for that.
Something to THINK about

As another data point, as someone who'd be on the surface and trying to coordinate things in an emergency, I think in this sort of situation where there is an entire team/program diving in challenging conditions, standard gases for the project would simplify things for me if something did go wrong and emergency personnel and rescuers were coming to me with questions to establish the details of the situation, as I'd very easily be able to say "this is what everyone is carrying, this is how it should be being used" without having had to make sure I checked in with everyone beforehand to find out what they'd decided to use that particular dive. (Last thing divers want when they're getting ready for a dive is someone bothering them about that sort of thing, anyway.)

(Not saying that means standard gases should be used because it makes it easier for surface teams to keep track of things no matter what the actual divers think, just pointing out that there can be benefits for people who are on the team but not diving, too. If you see what I mean.)

 

[Kay Dee]

See a lot of references to deceased being narced in this thread. Do we know this for a fact (i.e. he was known - by his dive partners - to be susceptable to narcosis) or just assuming such because of the depth?

 

[PfcAJ]

See a lot of references to deceased being narced in this thread. Do we know this for a fact (i.e. he was known - by his dive partners - to be susceptable to narcosis) or just assuming such because of the depth?

It’s physiological. If you’re not on helium at those depth, you’re impaired.

 

[steinbil]

See a lot of references to deceased being narced in this thread. Do we know this for a fact (i.e. he was known - by his dive partners - to be susceptable to narcosis) or just assuming such because of the depth?

Are you implying that there are people that are unaffected by gas narcosis at 190ft/58m on a nitrox mix? Now I’m not saying there aren’t any differences in tolerance, or that people don’t experience the narcosis differently, but from what I’ve read/heard it seems to be universally recognized that we are all affected by narcosis whether we notice it or not, and that this depth would be way past any limit of significant gas narcosis…

 

[Nitrogenius]

See a lot of references to deceased being narced in this thread. Do we know this for a fact (i.e. he was known - by his dive partners - to be susceptable to narcosis) or just assuming such because of the depth?

Also keep in mind that on a CCR without Helium in the mix the actual Narcotic equivalent depth is even deeper than with air depending on the chosen setpoint.
With 1.3 assumed that would actually increase the depth compared to air from 58 to 60 m..
There is no doubt that any diver is in fact impaired as such a depth..

 

[steinbil]

Also keep in mind that on a CCR without Helium in the mix the actual Narcotic equivalent depth is even deeper than with air depending on the chosen setpoint.
With 1.3 assumed that would actually increase the depth compared to air from 58 to 60 m..
There is no doubt that any diver is in fact impaired as such a depth..

Please excuse my ignorance about rebreathers, but how so? If you increase the ppo2, arent you just adding O2 and effectively making a richer nitrox mix in the loop? And if nitrogen and oxygen are equally narcotic, how would that change the END? Is there something I’m missing?

 

[Wibble]

Please excuse my ignorance about rebreathers, but how so? If you increase the ppo2, arent you just adding O2 and effectively making a richer nitrox mix in the loop? And if nitrogen and oxygen are equally narcotic, how would that change the END? Is there something I’m missing?

Theory is helium is really cheap on a rebreather as you use so little, so there’s no reason to dive CCR without helium.

 

[formernuke]

Theory is helium is really cheap on a rebreather as you use so little, so there’s no reason to dive CCR without helium.

.
That's the reason I got a rebreather