Fiona Sharp death in Bonaire

[skippy311]

Ar dheis Dé go raibh a hanam

Not necessarily. She could certainly tox deep and happen to be positively buoyant, the loop venting as she ascends until it floods completely making her negative enough to settle on the reef at 24m. Not saying that's what happened, but it's a possibility.

Scrubber duration may or may not be a factor. Was she re-using a scrubber that already had time on it? Was it packed improperly leading to channeling? She would have to have purposely avoided bailing out, CO2 doesn't just go from fine to unconscious. And with a BOV, there would certainly be ample warning and opportunity to bail off the loop, first by switching to BOV, and then switching to her offboard gas. One of the benefits of a BOV is that you don't have to do the switch to a second stage while being physiologically incapable of holding your breath, so the idea that she took a CO2 hit and that's what killed her is kind of far-fetched. Not saying it's impossible, but fairly unlikely unless there were other contributing factors as well.

 

[Kinasi]

Ar dheis Dé go raibh a hanam

What does that mean?

 

[wedivebc]

What does that mean?

It's Irish. Google it.

 

[Dan]

On the right hand of God was his soul

 

[DiverLaura]

Last dive of trip after a number of tech range dives, correct?

Any chance she was doing a washout dive (high PPO2 deco at the deep stops) and combined with the PPO2 spike at depth, Hyperoxia simply bit her in the ass? (I've read through the entire thread and didn't see it mentioned).

For folks wondering what I'm talking bout, there was a practice in my generation of tech divers (early to late 90's) to run -very- hot deco especially after a series of dives when flying home was in the cards OR you felt a little subclinical niggle. Perhaps a deep dive to crush the bubbles and then hot deco at the 70-80' stop to 'wash' them essentially self treating. PURE speculation just tossing it out there, but it wouldn't be the first time the practice killed a very very experienced diver.

 

[dmaziuk]

Hmm. 70-80' would be about at the bottom of the wall near Buddy's.

 

[Peter69_56]

Not necessarily. She could certainly tox deep and happen to be positively buoyant, the loop venting as she ascends until it floods completely making her negative enough to settle on the reef at 24m. Not saying that's what happened, but it's a possibility.

Scrubber duration may or may not be a factor. Was she re-using a scrubber that already had time on it? Was it packed improperly leading to channeling? She would have to have purposely avoided bailing out, CO2 doesn't just go from fine to unconscious. And with a BOV, there would certainly be ample warning and opportunity to bail off the loop, first by switching to BOV, and then switching to her offboard gas. One of the benefits of a BOV is that you don't have to do the switch to a second stage while being physiologically incapable of holding your breath, so the idea that she took a CO2 hit and that's what killed her is kind of far-fetched. Not saying it's impossible, but fairly unlikely unless there were other contributing factors as well.

A question for you, have you ever had a CO2 hit? Are you speaking from experience or from what you know?

I am not trying to be smart ro have a go at you, but I ask for the following reason.

I have never had a CO2 hit but have had a caustic hit. I have however had a friend who had a CO2 hit from a canister that had come loose in his breather. His description to me was the following. "I felt something was wrong, just didnt feel right. I cleared the loop with DIL. This seemed to sort me so I continued on. A little while later I knew something was wrong and signaled to my buddy (his instructor) that I was aborting. At that stage I couldnt think properly and developed a huge migraine. I had only to swim maybe 15m to the shot line. I couldnt even get my head right to bail. It was only that my buddy was there who helped me switch, and helped me through the deco stops. I had such a blinding headache I could not function at all and just wanted to roll up into a ball". It wasnt until I got back on the boat, and was on O2 for some time before I regained some sort of functionality".

Now they are his words and his experience, so to say someone could not have died from a CO2 hit think is wrong. I can see from his experience where someone could easily stop functioning and just give up. Specially if a solo rebreather.

I agree the BOV gives you a chance to swap over, but it doesnt mean you have the ability or capacity to with a CO2 hit. From the description above, I would suggest my friend would not have been able to change over. With my caustic hit, I could have but would not have wanted to breath from a contaminated BOV, hence why I have a BOV but also a reg on each bailout tank as well as an LP line.

Thats my thoughts anyway.

 

[Peter69_56]

I worry about a depressed PPO2, or hypoxia, on every CCR ascent since it's a potential "shallow water blackout" situation. As you ascend, you have to vent, vent, vent in order to not start a runaway ascent. You must be sure to add enough 02 in order to drive your PPO2 up to counteract this.

And there is the rub. You are dumping from the loop because as you ascend, the loop volume grows, but at the same time the PPO2 drops so you have to add oxygen. So you are adding gas and dumping gas at similar times. If your unit is badly designed and the oxygen add outlet is near the dump or relief valve you can be adding oxygen and dumping it at the same time if you dont do it right.

 

[Peter69_56]

Precisely. None of us want to be 'next'. It's not ghoulish: it's survival. When a noob dies, we shake our collective heads, cite the need for better training, honoring their limits and/or hubris. The ocean is a harsh mistress and doesn't suffer fools. But, when an experienced diver dies, it gives us a certain pause. "If they aren't safe,then who is?" Here in cave country, we are often chastised for wanting to know what happened. They claim it's not our right to know and they always couch simple reasonable requests as demanding answers right this instant. This is not the same as rubbernecking at an accident. Not even close. We want to know how and why our heroes die. So, as Sam so aptly pointed out, we might possibly avoid the same mistake.

So true "There but for the grace of GOD go I"

 

[RainPilot]

And there is the rub. You are dumping from the loop because as you ascend, the loop volume grows, but at the same time the PPO2 drops so you have to add oxygen. So you are adding gas and dumping gas at similar times. If your unit is badly designed and the oxygen add outlet is near the dump or relief valve you can be adding oxygen and dumping it at the same time if you dont do it right.

GENERALLY speaking, the dil will be added on the inhale side and O2 on the exhale. This is to allow the O2 to mix on its way through the machine, avoiding localised spikes (If you, for example, breathed very rapidly and O2 was being added just before the mouth, you could be breathing next to pure O2 as the machine tried to raise the set point)

This design is to avoid the issue you mention, as well as to allow you to immediately get the "good gas" if you need to do a dil flush in case of a hot loop composition. Thats not to say all units are like that, but it is a pretty constant design paradigm in the industry.