Fiona Sharp death in Bonaire

[jstrang]

For this dive there really is not much of a helium penalty. whether you have 20/20 or air the deco schedule for the 15 minute bottom time is nearly the same.

I still think the high wob due to gas density and the high pO2 at that depth would have led to increased risk of toxing. Even after she started her ascent she would have endured 20-25 minutes of high O2 levels. Her levels would not have been below 1.4 until she reached ~180 feet and wouldn’t be below 1.0 until she reached 100’. High CO2 and high O2 for that length of time would be disastrous for all of us.

 

[John Bantin]

Facts sent to me from an Insider:

Of course, if you have pertinent information you feel should be passed on, I am here for you. I will only pass on info at my discretion that I feel to be reliable.

That was the same information given to me.

 

[rjack321]

I don't dive an mCCR, but interested in the terminology. I'm using the term "setpoint" to mean your target PO2, but it seems that you are using it to mean current PO2, right? Help me understand...

On either eCCR or mCCR, if you decide that you want to be at a PO2 of 1.3, that's your setpoint. On eCCR the solenoid makes up for the continual drop from metabolism, whatever your workload is, based on the sensors. On mCCR, your orifice is chosen to let O2 into the loop at just below metabolic rate, and it's up to the diver to use the MAV to maintain the setpoint. If you don't pay attention and use the MAV, the PO2 will drop, as will hard work, ascending or a clogged orifice. But the setpoint doesn't change, even if you don't maintain it, by my definition of the term.

Setpoint is really a eCCR term IMHO. You cant "set" a mCCR to do anything.

On mCCR setpoint = current ppO2, they are one in the same. Which might not be the desired ppO2 but there is nothing to change it but manually adding. I guess you could have "current ppO2" as opposed to "desired setpoint" on mCCR but its a contrived thing.

Fiona's inspo is an eCCR but I don't know how she ran it. Low SP parachute vs active eCCR or something else

 

[doctormike]

Setpoint is really a eCCR term IMHO. You cant "set" a mCCR to do anything.

On mCCR setpoint = current ppO2, they are one in the same. Which might not be the desired ppO2 but there is nothing to change it but manually adding. I

Got it, that makes sense! Thanks... I just use the term to mean "desired PO2". I figured that you "set" an mCCR to the desired PO2 with your brain.

 

[rjack321]

For this dive there really is not much of a helium penalty. whether you have 20/20 or air the deco schedule for the 15 minute bottom time is nearly the same.

I still think the high wob due to gas density and the high pO2 at that depth would have led to increased risk of toxing. Even after she started her ascent she would have endured 20-25 minutes of high O2 levels. Her levels would not have been below 1.4 until she reached ~180 feet and wouldn’t be below 1.0 until she reached 100’. High CO2 and high O2 for that length of time would be disastrous for all of us.

Why do you think her ppO2 would have been that high?

On eCCR its fairly easy to breath the loop down, especially on a long gradual swim. She could have easily been at 1.1-1.3 at 91m. WOB would have been quite high but not necessarily ppO2.

 

[jgttrey]

I do think there is a lot of good learning going on in this thread, even if ultimately much of it proves to be on topics unrelated to the cause of this tragedy. To me, that's the point of A&I. It isn't some scuba star chamber of armchair quarterbacks, or it shouldn't be. I think the latter is what some people think and react against.

Much good information posted so far. I'd be curious what the time at depth was and whether the computer download showed controlled stops prior to 80' that would be indicative of a controlled ascent and following a deco schedule as part of a planned 300' dive.

I'm still having a hard time wrapping my head around the idea that this was a planned 300' dive given the DIL choice, BO gases, and quantities thereof. But, if the profile shows a typical dive profile with some "stable" time spent at depth and controlled stops per deco schedule leading up to whatever happened at 80', then that would strongly suggest the dive was planned. It would also mean that much of our discussion about gas density, narcosis, BO amounts, etc. is less relevant, perhaps not irrelevant, but less relevant to the immediate cause of a problem at 80'.

 

[jstrang]

Why do you think her ppO2 would have been that high?

On eCCR its fairly easy to breath the loop down, especially on a long gradual swim. She could have easily been at 1.1-1.3 at 91m. WOB would have been quite high but not necessarily ppO2.

Her dil pO2 would be 2.0 if she was using 20/20 at 300’ - as soon as she activated her adv it would be high. I get that she could metabolize some of it down but as soon she does she has to replace that loss of loop volume with a high pO2 mix.

My experience has been on wrecks and walls that went down to 300’+ with a high He mix so admittedly I don’t think I’ve ever tried to use up O2 to lower my actual pO2 all I’ve had to do is Fire the adv to bring my pO2 down.

My recollection of running it manually with a low set point was it didn’t change quickly. At that depth I was basically just using the diluent for both O2 and loop volume.

it would be informative to see what her actual pO2 was through the dive. Maybe someone will let us know if she was able to keep it lower than 1.6.

 

[tursiops]

So that means 20/20 dil, right? So leaving aside the hot loop issues, that's still an END of 218 FSW.

What does "setpoint controller and computer set to air" mean? Not sure I understand that in the context of CCR. Her decompression stress was calculated with her computer set to air OC bailout? What was the setpoint?

Her dil was air.

 

[Wookie]

Her dil was air.

No. Her dil was 20/20. Confirmed by multiple sources.

 

[tursiops]

No. Her dil was 20/20. Confirmed by multiple sources.

Well, that's interesting, since air was confirmed by multiple sources.
I'll see what I can track down.....there are not that many first-hand sources here (I'm still at Buddy Dive).