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

[DOBY]

Isn't one of the main advantages of CCR that HE can be used below 100 ffw at reasonable expense.

I am not a CCR or trimix diver, but I would think for that dive (planed 190 ffw, floor 200 ffw) you would want a trimix with END <= 100 ffw at depth of 200 ffw, and O2 MOD >= 200 ffw for BO (and therefore DIL).

Yes! CCR’s use a lot less Helium. And it’s not complicated to calculate an appropriate diluent.

First you want a pO2 at maximum depth to be around 1.0ata so as to be able to flush down any O2 spikes.
(1) 1.0ata/((190+33)/33) x 100 = 15% O2

Next you want the END ~ 100ft so set pN2 to around 3.2ata
(2) 3.2/((190+33feet)/33) x 100 = 47% N2

The rest is Helium
(3) 100% - 15% - 47% = 38% He

Trimix 15/40 would have been a good mix for a 190 foot dive, especially if task loaded.

The first thing learned in a basic Enriched Air course is that Nitrox is not to dive deeper, but to increase NDL or lower decompression time. It actually requires you to dive shallower. This dive plan makes no sense. Using a Nitrox mix beyond it’s MOD and adding additional O2 via a manual orifice is a very bad dive plan. The only way to make it work is to shut off the O2 and breathe down the pO2 as you descend - which is a very bad dive plan!!!!

 

[tbone1004]

Glad the report is out, will be curious to see how we interpret the findings to improve our own diving.

 

[Vicko]

Did the victim have a dil MAV? I didn’t find that in the report. Per the KISS website, an O2 MAV is standard with an ADV for SW.

Report states he was adding a lot of o2 on descent, since his dil was already rich enough to give 1.8ppo2 on the bottom the only sensible reason (that I can think off) to add o2 is if somehow there was a mixup with some form of dill addition.

 

[Trouts]

Did diver 3 and the victim both have (what they thought to be) EAN 24? Granted I don't know a ton but from the report it would seem that would have been unsafe to go to 190 for either of them. And if they didn't have the same gas set up, why not? You would think a team would have a standard set of gas if the divers are working together on the same project?

Diver 3 had an appropriate gas for their planned dive, as did all other team members diving that day (besides the victim). Standardized gases were used for all safety and deco bottles. Individual team members were responsible for filling, analyzing, and labeling their own personal side-mount bottles. Typically a mix of 15/50 was used for dives to that depth. (I say "typically" because team members with plans to go deeper than the 220 ft restriction brought gas suitable for those planned dives- and also may have used them for shallower setup dives).

Gayle Orner

 

[DOBY]

Report states he was adding a lot of o2 on descent, since his dil was already rich enough to give 1.8ppo2 on the bottom the only sensible reason (that I can think off) to add o2 is if somehow there was a mixup with some form of dill addition.

The Sidewinder is a mCCR which has a manual add valve (MAV). But there is also an orifice that continuously adds a small amount of O2. I think the NSS-CDS report is referring to the small, continuous addition of O2 via the orifice and not actively adding O2 via the MAV on descent. As the report states there was no in-line oxygen shutoff valve and the oxygen tank valve was found in the open position.

 

[hehatemefrisbee]

Diver 3 had an appropriate gas for their planned dive, as did all other team members diving that day (besides the victim). Standardized gases were used for all safety and deco bottles. Individual team members were responsible for filling, analyzing, and labeling their own personal side-mount bottles. Typically a mix of 15/50 was used for dives to that depth. (I say "typically" because team members with plans to go deeper than the 220 ft restriction brought gas suitable for those planned dives- and also may have used them for shallower setup dives).

Gayle Orner

Thank you for the info. I wonder if an update to the SOP's would include verification of each other's tank analysis and gas plan.

 

[DiveTucson]

I am curious based on the gas he was carrying and the apparent planned dive why someone on the team didn't stop the dive from moving forward. It is clear to me based on the report that the entire plan was to do the dive and place the deep(ish) bailout while using the 24-26% diluent. This makes no sense for so many reasons...

 

[inquis]

I think the NSS-CDS report is referring to the small, continuous addition of O2 via the orifice and not actively adding O2 via the MAV on descent.

However, that continuous addition should be removed by metabolism (unless set incorrectly). Perhaps the non-official 1.8 atm ppO2 early report mentioned above was in error. Certainly seeing the time-history of the ppO2 would have been useful.

 

[lostsheep]

Dive team to keep permit following 'tragic accident' at Roaring River spring, state says

A long-standing policy states that dives must be for scientific and interpretive purposes only.

www.news-leader.com

 

[L13]

Thank you for the info. I wonder if an update to the SOP's would include verification of each other's tank analysis and gas plan.

Unless your buddy's gases are not considered part of your backup gases, I would think you would always want to know what they were carrying and where for selfish reasons. Since I don't dive at that level, I don't know what the norm is. A big reason I'm reading this and similar threads is to learn since I hope to expand my dive envelop safely.