Two Divers from same boat die in a week

That's too bad. That is a deep dive, so both divers are not >500 dives / rec. divers. At that depth it will be rebreathers and mixed gas. It will be interesting to see what the autopsy and equipment reports come back with.

Ok, here is my take.....coming from a diver of 200+ dives from easy to deep technical...that type of dive is left for commercial, research dedicated divers. The tables don't exsist for the novice, the Navy sat divers, yes, with decon chambers aboard the vessel. Being the guy was 64 years old says either he was "very, very accustomed to this type of dive", or he needed to be Jack Lalane in condition.
It really didn't matter what type of air supply he was using, being rebreather, mixed gas, or just plain air. A diver could do a "bump dive" to that depth on any supply, but the decon time would be crazy.
I think that in order to do any dive below the stated Navy tables, you have to show advanced certification documentation to be allowed that type of profile. Maybe he had all of that, but two deaths in that time span.....not so much.
Gods speed to him and his family

He couldn't do it on straight air. Not anywhere near that depth on straight air. He's be narked (nitrogen narcosis) out of his brain at 125' and the partial pressure at 180ish feet becomes an issue. >200 feet rebreathers are out and compressed air will kill you. >215 feet, Oxygen toxicity will kill you. Trimix will take you down to about 350'.

Anyone getting on a dive boat doesn't get in the water with rebreathers, trimix, heliox, or even nitrox for that matter doesn't do so without showing cert cards, DAN insurance card, etc.

If he came out of the water in cardiac arrest, that could have been a dive issue from not following deep dive accession and deco procedures, or it could have been another issue. He very well could have had a heart attack down there and bolted.

A quick look at his dive computer will give you the profile and answer a lot of the questions and speculation.

I have bumped dives better than 130' on regular air and done a multiple profile the same day using my computer. Yes, you are right, he might have had an physical issue at the bottom which caused him to bypass his decon stop in search of rescue. But even though they might be popular dives in that area, they are also technical by any standard when they bypass regular compressed air/mixed gas/ below 120' feet. It is just not for a recreational diver to try.
Hope they find the answers.....

what happened to 30' for 45min, and a cold beverage and a lounge chair? Hey, to each their own, smoke em' if you got em', but at 64 he should have been looking at other distractions....just saying. I know I would have rather gone on doing something much, much more fun.
Party on,

Two divers on the same boat, granted not on the same dive, but same boat. That's bad juju.

I'd be interested and will follow the story to see his dive computer / profile.

Sorry, but I've got over 4,000 dives and 125' on air is NOT an issue...I've taken a few hundred divers to that depth and never had a problem w/ nitrogen narcosis - not to say someone might not have felt giddy or the like, but nothing that caused anyone to do anything irrational which is the real danger w/ nitrogen narcosis.

I'd also have to look more closely at the depth at which the partial pressure of O2 becomes a real danger but it's not "180-ish" as I've been there on air and know lots of others who have and have had no problem...(all in the clear, warm, light-current waters of the Caribbean).

Again, everyone's physiology is different and that's not to say someone won't get narced at 125' and that someone else won't have an O2 pp problem at 180' but most people won't.

I know this for a fact though: for every depth below 150' you're going to increase the technical/complexity/danger level exponentially. Add in cold water, low vis, strong currents and that kind of diving is limited to the very, very few.

A very large downside risk for 15 minutes of poking around in the dark...

I could have written this post down to the numbers of dives and completely agree.

The effects of N2 narcosis differ from person to person. I know people who can't dive on air deeper than 90' because they get to paranoid but I also know people who claim to control their narcosis and dive to 180'. There is this PSAI Narcosis Management course. I've not done this course because I limit myself to 150' and only go there if it is worthwile.

I haven't read the article but guess that the cause of death could also have been a PFO.

Tests have shown that every body gets narc-ed and impaired starting at basically the same depth. Saying you can control it is much the same as saying you have driven drunk enough times that you can handle that just fine too.

"Scientific evidence does not show that a diver can train to overcome any measure of narcosis at a given depth or become tolerant of it."

There are many variables that come into play at that depth. Body temp., basic physical condition, hydration, physical exertion leading to co2 build up, etc.

While those depths have been and can be reached on air (21% O2), these days any sane person is using mix gas to get there.

As far more than one diver dieing on the same boat, just Google the dive boat "Seeker" and it's history. It's not uncommon.

I'm happy to talk scuba shop with anyone at any level of granularity.
I've taught deep diving classes with students that get 'tipsy' at 100' and others that get tipsy at 130. Every body reacts differently. We agree on that.

Just how long do you expect your bottom time to be on compressed air @ 150? I'll wait here while you research PP02 tables.

Cheers-

That is a foolish endeavor to begin with, but I can tell you from personal experience that you can spend 12 hours on the bottom at 1700 meters on about a 1/3 of a single 80.

Steel 95, I can see.... but an 80? no way.....

Hi,

You might find there is more to Marmots answer than the actual physical item quoted to give a volumetric comparison.

Evidently I'm terrible at reading code between the lines.