Scuba diver dies while exploring popular shipwreck, a third tragedy in the Florida Keys

[Biotech Diver]

Umpman & Biotech Diver...

MOD for 32% at sea level with an ATA of 1.4 is 111 feet.
Are you suggesting to use 32% at sea level with an ATA of 1.6 during a working part of a dive to 132 feet is ok?

WTF do you think I said "Yup" in response to your post and gave you a thumbsup?

 

[boulderjohn]

You don’t have any minutes on 32% at 130 feet.

The PADI EANx32 tables give you 18 minutes at 130 feet.

 

[formernuke]

The PADI EANx32 tables give you 18 minutes at 130 feet.

Look closely, says exceeds 1.4

 

[boulderjohn]

Look closely, says exceeds 1.4

...and? Does that mean it can't be done?

The PADI course lists 1.6 as the contingency limit. You are not supposed to plan dives that deep, but if end end up doing it, the tables give you a limit.

 

[scubadada]

I apologize if I missed it, has any additional information been released since the diver was found inside the wreck by divers from Horizon Divers? Specifically, was the diver out of gas or not?

Sorry to return to the original thread topic, did we ever hear anything about the cause of this death?

 

[Dan G]

Looks that way to me. Sadly not the first person on this forum to say 1.6 is ok for working part. But you can't fix stupid, only Darwin can.

This is where I disagree. You can fix this b/c the diver may simply have been told by someone with more experience that 1.6 is OK for the working portion of the dive. It's not ideal to be at 1.6 for long, but it's not as if a diver suddenly implodes when they hit 1.6 ATA.

I can totally see a situation where a newer recreational diver with limited experience talks to a more experienced diver on the boat after a dive and is told, "I hit 1.6 and I'm fine." The newer diver doesn't know the context of that diver's experience and decides that 1.6 is fine all of the time and for an unlimited amount of time. You may call that stupid, I just think that's what happens in diving sometimes. We pick up stuff from those around us and we don't always know what to toss in the garbage and what's good advice.

 

[Norwegian Cave Diver]

If the diver has taken and passed a nitrox course then they should KNOW that 1.4 is the working number and 1.6 is the resting number that is considered acceptable.
If they haven't taken a nitrox course well then good luck...

 

[boulderjohn]

If the diver has taken and passed a nitrox course then they should KNOW that 1.4 is the working number and 1.6 is the resting number that is considered acceptable.
If they haven't taken a nitrox course well then good luck...

That is only the standard procedure for technical diving with decompression stops. Recreational divers are taught in most nitrox classes that 1.4 is the regular standard, and 1.6 is called the "contingency standard," meaning that it is acceptable to go to that depth briefly for various reasons, but should not be planned that way. As I noted elsewhere, the PADI EANx 32 tables give a maximum bottom time of 18 minutes at 130 feet (1.6).

 

[boulderjohn]

It's not ideal to be at 1.6 for long, but it's not as if a diver suddenly implodes when they hit 1.6 ATA.

Many people do get the idea that if they exceed 1.4, they will instantly go into convulsions, but toxicity takes a longer exposure than that. I have not done any sort of sophisticated study, but every single case of oxygen toxicity of which I am aware came on a technical dive with prolonged exposures. I am not aware of any cases of toxicity on a recreational dive with divers using AL 80s. I would be happy to review such a case if anyone can direct me to it.

Here are some cases I know of. You can do the math on them.

• A diver who had been laid up with an injury for months went on a dive to a wreck (Hydro Atlantic--deck at 150 feet) using double tanks he thought were filled with air. He had been on the wreck, probably at an average depth of 160 feet, for a while before he toxed. His tanks had 36% nitrox.
• A diver at Ginnie Springs in Florida went to the bottom (about 100 feet) breathing from a stage bottle he thought had air in it, but it was filled with oxygen. I don't know how long he was breathing oxygen at 100 feet before he toxed.
• A WKKP cave diver was in a group that was supposed to drop their 50% bottles off at a depot at 70 feet before descending to the bottom, breathing off a different gas mixture in a similar tank. The diver accidentally left his bottom stage at the depot and descended with the group to 200 feet while breathing from the 50% tank. I don't know how long he was at 200 feet before he toxed.
• A diver using a prototype rebreather did what was planned to be a short photography dive in Jackson Blue in Marianna, Florida. He used a diluent of 57%, apparently hoping to drop the mixture down to a safe level in the cavern before descending the chimney to about 100 feet. He and his buddy were at 100 feet for a while before he toxed. His buddy's incredible rescue skills saved him. When we recovered his gear, his O2 bottle was empty--it should have been nearly full. We can't be sure what his actual O2 percentage was when he toxed, but it had to be high. (Because he lived, he didn't have to release any details, and he didn't.)

 

[rx7diver]

If the diver has taken and passed a nitrox course then they should KNOW that 1.4 is the working number and 1.6 is the resting number that is considered acceptable.
If they haven't taken a nitrox course well then good luck...

FWIW, I took my Recreational Nitrox course in 1993. We used Dick Rutkowski's "Enriched Air Nitrox" text. We were taught that PO2 = 1.6 ATA was the recreational limit, and that this should be dialed back for arduous diving (like diving in Lake Superior or diving in currents).

rx7diver