Fatality off Pensacola - Read and learn

[Tortuga68]

YES

Was your max depth less than one metre? If not I think you'll find you spend some time on the descent and ascent, and maybe a safety stop as well

You dont know this!!! 1.4pp02 is not a guarentee.

Exactly. People have toxed under 1.4, even at 1.0. There are a lot of other factors to consider than just the PP

1.4 is considered a safe margin for the working portion of the dive by many agencies. Going over it by 5% isn't going to be the sole difference between living & dying

 

[Hatul]

Have you ever done a dive where the entire dive time was at the maximum depth?




Sounds like an equipment solution to a skills problem

Also 0.076 bar over 1.4 PP isn't going to kill anyone

About the O2 toxicity, I used to think that as well, until we had a case of a diver convulsing on an 8 minute dive at ppO2 of 1.49 bar. There are many factors that go into oxygen toxicity such as CO2 level, exertion, cold and individual factors. Since a convulsion at depth is likely fatal it's just bad idea to plan a dive to a ppO2 of 1.47. I've set my computer to max ppO2 of 1.3 bar after reading that case report and the Dan article.

 

[Tortuga68]

About the O2 toxicity, I used to think that as well, until we had a case of a diver convulsing on an 8 minute dive at ppO2 of 1.49 bar. There are many factors that go into oxygen toxicity such as CO2 level, exertion, cold and individual factors. Since a convulsion at depth is likely fatal it's just bad idea to plan a dive to a ppO2 of 1.47. I've set my computer to max ppO2 of 1.3 bar after reading that case report and the Dan article.

I really think you're just making my point for me... you've decided to use 1.3 now instead of 1.4. Some people use 1.2 or even 1.0. They're arbitrary numbers designed to provide what the diver thinks is an acceptable safety margin. If you choose 1.3 and exceed it by 5% are you "gunna die" just because of that?

People have toxed under 1.0 and people have not toxed at 3.0. As you - and I - said, there are a lot of other factors. In the dive in question, we don't know if the dive was planned at 1.47; what the exposure was; work level; environment etc.

As ahava pointed out, 1.4 or 1.3 or whatever is no guarantee of not toxing

 

[Hetland]

About the O2 toxicity, I used to think that as well, until we had a case of a diver convulsing on an 8 minute dive at ppO2 of 1.49 bar. There are many factors that go into oxygen toxicity such as CO2 level, exertion, cold and individual factors. Since a convulsion at depth is likely fatal it's just bad idea to plan a dive to a ppO2 of 1.47. I've set my computer to max ppO2 of 1.3 bar after reading that case report and the Dan article.

And there are probably thousands, if not, tens of thousands of dives safely completed each year with a ppo2 of over 1.4

I think the mix was a tad rich myself, but I seriously doubt it was a significant factor in this fatality.

 

[ahava]

Was your max depth less than one metre? If not I think you'll find you spend some time on the descent and ascent, and maybe a safety stop as well

Yes it was. I think its obvious that time is spent on decsent and ascent.

 

[shmuggy]

No- safety stops are too important and this diver did all he should have to assist the diver. It was up to the boat crew to be looking out for their divers as they ascended and to assist them at the surface. Also, the diver may have been in a panic when he left the octopus presenting a danger to others. This was a very sad situation all round.

 

[Tortuga68]

I think its obvious that time is spent on decsent and ascent

Then you didn't spend the entire dive at max depth. Even on a square profile dive to 102', you're usually going to spend at least ~9 minutes on descent, ascent and safety stop, which on a 35 minute dive would mean only 75% of your dive time was at the bottom, reducing the nitrogen loading and the required decompression

 

[Hatul]

And there are probably thousands, if not, tens of thousands of dives safely completed each year with a ppo2 of over 1.4

I think the mix was a tad rich myself, but I seriously doubt it was a significant factor in this fatality.

I agree with you, however it's a risk-benefit situation and you don't gain that much by using more oxygen while cutting your safety margin. You have to decide for yourself what that safety margin should be. For me I would not take EAN36 on a 102 ft dive. Nevertheless, as someone pointed out this does not appear to be a factor in the death, but it may be a sign that some of the divers at least were not overly safety conscious IMO.

 

[motorref]

I agree with you, however it's a risk-benefit situation and you don't gain that much by using more oxygen while cutting your safety margin. You have to decide for yourself what that safety margin should be. For me I would not take EAN36 on a 102 ft dive. Nevertheless, as someone pointed out this does not appear to be a factor in the death, but it may be a sign that some of the divers at least were not overly safety conscious IMO.

I realize that this incident is long past, but I've been "trolling" the Accidents and Incidents" forum for things to look out for and learn from. That they were exceeding the recommended depth my first thought as well, although being a newbie I had to look it up to be sure that the recommended limit on 36%EAN is 95 ft. If they knew the bottom was @ 102, why use 36% instead of 32%?

Confused, but learning,
Kevin L

 

[ahava]

Then you didn't spend the entire dive at max depth. Even on a square profile dive to 102', you're usually going to spend at least ~9 minutes on descent, ascent and safety stop, which on a 35 minute dive would mean only 75% of your dive time was at the bottom, reducing the nitrogen loading and the required decompression

Sorry if you noticed on my origional post I stated that if you stayed at that depth for the entire dive. I used that 35 min. as bottom time. I have had many square profiles to those depths and times. Sorry I wasnt trying to split hairs with my statement!!