One dead, one missing (since found), 300 foot dive - Lake Michigan

[John C. Ratliff]

Okay, I need to wrap my head around some rather new concepts (to me at least).

--To me, recreational Scuba is always open circuit Scuba. This couple apparently were diving CCRs, which to my way of thinking is not recreational, but rather technical diving.

--Again, to me, recreational Scuba is accomplished within the no-decompression limits, and at a depth no greater than 130 feet of sea water (5 atmospheres absolute pressure, 40 meters).

Yet, these news reports, and some here, are referring to these kinds of dives (300 feet on CCRs) as recreational dives. Why?

In order to accomplish a dive on CCR, the gas mixture must be carefully calculated, and most likely includes the use of helium in the mixture (to preclude nitrogen narcosis) and reduced oxygen levels. These levels of oxygen must be automatically increased, or a switch made to alternate gas supplies, when surfacing if my understanding of diver physiology is correct (docs, help me out here). In doing an emergency swimming ascent from 300 feet, would the CCR be able to change the oxygen level fast enough to sustain consciousness?

This level of support needed for a complex dive to 300 feet on CCR is not available on just any dive boat, in my opinion. This is more like an expedition than a recreational dive, but was not treated as such.

Lastly, I spoke last year to Spencer Campbell, who conducted some of the original research on deep diving and decompression, and who oversaw the research dives on the Cobb Sea Mount. I asked him about the propriety of doing deep decompression dives without a recompression chamber immediately available, as many do today? His reply is that he would never contemplate doing those deep, decompression dives without a recompression chamber immediately available.

Just some thoughts from a vintage dive and long-time safety professional (now retired).

SeaRat

 

[Marie13]

If you're not diving as employment (commercial diving), then it's recreational, whether it's sport or technical flavors.

 

[Marie13]

Well, it does affect me a bit when people with tons more training than me perish.
As I was not there, I am not interested at all in discussing depth and circumstances or depths or equipment or choices or ... that might have could have made a difference.
Only replying to a direct question asked, because it was asked. If Moderators feel that does not belong here, I would agree:
Was I planning to do dives that deep?
Maybe not, who knows. But given time, funding, training opportunities etc... I was fancying a rebreather some day. Maybe still am. My main goal might be silence, stealth and duration over depth (observing marine life, taking pics...). But I just got tons of respect of the UW situation to begin with... and when highly trained people perish or get hurt ... I tend to get more...
That‘s all...

You're an engineer, are you not? OCD enough for rebreather, I'd suspect. No rebreather for me. Too expensive and I'm not OCD enough. I just throw my gear in my car and dry it off when I get home. Rinsing gear? That's only it's got gravel from the quarry on it. Don't dive salt, so that's not a concern. I much prefer low maintenance. A rebreather is just too danged high maintenance for me. The Great Lakes wrecks I love don't worry about my bubbles.

 

[Schwob]

You're an engineer, are you not? ...

A good one and well aware of what all can go wrong, hence the abundance of respect for the underwater environment...

 

[helodriver87]

If she made a direct ascent from 300', nothing short of a chamber on the boat would've saved her, and even that is extremely questionable. Support is obviously prudent in dives like this, but I don't think it would've made a bit of difference in this case. When you're dealing with depths/deco obligations like this, you have to understand that going to the surface for help, no matter how much you may need it, isn't a possibility. I don't know how this played out, and we may never know, but it's obvious that she blew off a ton of deco. Barring some bizarre combination of independent failures, it looks like a failure to remember that reality.

 

[Protondecay123]

Okay, I need to wrap my head around some rather new concepts (to me at least).

--To me, recreational Scuba is always open circuit Scuba. This couple apparently were diving CCRs, which to my way of thinking is not recreational, but rather technical diving.

--Again, to me, recreational Scuba is accomplished within the no-decompression limits, and at a depth no greater than 130 feet of sea water (5 atmospheres absolute pressure, 40 meters).

Yet, these news reports, and some here, are referring to these kinds of dives (300 feet on CCRs) as recreational dives. Why?

In order to accomplish a dive on CCR, the gas mixture must be carefully calculated, and most likely includes the use of helium in the mixture (to preclude nitrogen narcosis) and reduced oxygen levels. These levels of oxygen must be automatically increased, or a switch made to alternate gas supplies, when surfacing if my understanding of diver physiology is correct (docs, help me out here). In doing an emergency swimming ascent from 300 feet, would the CCR be able to change the oxygen level fast enough to sustain consciousness?

This level of support needed for a complex dive to 300 feet on CCR is not available on just any dive boat, in my opinion. This is more like an expedition than a recreational dive, but was not treated as such.

Lastly, I spoke last year to Spencer Campbell, who conducted some of the original research on deep diving and decompression, and who oversaw the research dives on the Cobb Sea Mount. I asked him about the propriety of doing deep decompression dives without a recompression chamber immediately available, as many do today? His reply is that he would never contemplate doing those deep, decompression dives without a recompression chamber immediately available.

Just some thoughts from a vintage dive and long-time safety professional (now retired).

SeaRat

Much less the temperature down there. Isn't the water temp near freezing at that depth there this time of year? Can you imagine have a free flow on your first stage or really anything important freeze up after 10 minutes at that depth?

 

[John C. Ratliff]

If you're not diving as employment (commercial diving), then this it's recreational, whether it's sport or technical flavors.

I don't really believe what you say here. Recreational diving to me is a form of diving whereby I can go diving almost spontaneously, with little prior planning. When I get to the site, then I need to take into consideration the conditions immediately in front of me, and take measures to either mitigate these hazards; decide to dive in spite of the hazards, and rely upon safety measures to protect me; or call the dive.

Now, in 1977 Ted Beoler re-wrote NAUI's dive manual. I was called the NAUI Pro Manual. Let me show you what the description for a "Deep Diving" course stated in that manual:

"Deep Diving
"This course is to provide the diver with the knowledge and skills to safely plan and make deep dives while avoiding the need for stage decompression. Deep diving is defined as dives made between 60 and 130 feet. Training dives are not to be conducted beyond 130 feet.

"Coverage is to include purpose, problems, hazards planning, preparation, equipment (additions and modifications), air supplies, personnel, techniques, emergency procedures including hyperbaric chamber location and transportation, plus depth limits for sport diving. Decompression procedures are to include: Nitrogen narcosis and decompression sickness (definition, cause, symptoms, signs, first aid, prevention), history of decompression, concepts, definitions of terms, problems, principles, and techniques. Complete coverage of the Repetitive Dive Tables, work sheets, problem solutions, exceptions and dive planning are also to be included. Altitude diving, flying after diving and hyperbaric chamber access and operation should be included, as well as other short- and long-term deep diving hazards."

SeaRat

 

[helodriver87]

I don't really believe what you say here. Recreational diving to me is a form of diving whereby I can go diving almost spontaneously, with little prior planning. When I get to the site, then I need to take into consideration the conditions immediately in front of me, and take measures to either mitigate these hazards; decide to dive in spite of the hazards, and rely upon safety measures to protect me; or call the dive.

Now, in 1977 Ted Beoler re-wrote NAUI's dive manual. I was called the NAUI Pro Manual. Let me show you what the description for a "Deep Diving" course stated in that manual:

"Deep Diving
"This course is to provide the diver with the knowledge and skills to safely plan and make deep dives while avoiding the need for stage decompression. Deep diving is defined as dives made between 60 and 130 feet. Training dives are not to be conducted beyond 130 feet.

"Coverage is to include purpose, problems, hazards planning, preparation, equipment (additions and modifications), air supplies, personnel, techniques, emergency procedures including hyperbaric chamber location and transportation, plus depth limits for sport diving. Decompression procedures are to include: Nitrogen narcosis and decompression sickness (definition, cause, symptoms, signs, first aid, prevention), history of decompression, concepts, definitions of terms, problems, principles, and techniques. Complete coverage of the Repetitive Dive Tables, work sheets, problem solutions, exceptions and dive planning are also to be included. Altitude diving, flying after diving and hyperbaric chamber access and operation should be included, as well as other short- and long-term deep diving hazards."

SeaRat

This is really pedantic. Obviously, recreational diving is anything that's, well, recreational in nature. As in, we do it for enjoyment rather than employment. Within the diving community, there's a fairly well established delineation between technical and recreational diving. Most technical dives are recreational in nature, but fall well outside the scope of recreational diving.

 

[Bob DBF]

Yet, these news reports, and some here, are referring to these kinds of dives (300 feet on CCRs) as recreational dives. Why?

Because commercial and Military salvage divers would never attempt those dives on that equipment. Also, of course, because the divers are doing this as a recreational activity.


Bob

 

[doctormike]

Okay, I need to wrap my head around some rather new concepts (to me at least).

--To me, recreational Scuba is always open circuit Scuba. This couple apparently were diving CCRs, which to my way of thinking is not recreational, but rather technical diving.

--Again, to me, recreational Scuba is accomplished within the no-decompression limits, and at a depth no greater than 130 feet of sea water (5 atmospheres absolute pressure, 40 meters).

Yet, these news reports, and some here, are referring to these kinds of dives (300 feet on CCRs) as recreational dives. Why?

Marie already said it, but in some countries there are stricter definitions than in others. This is really a semantic issue that varies from venue to venue.

@Wookie will explain it best, but I believe that there are four main classifications: commercial diving, military diving, scientific diving and everything else. Everything else is "recreational", even if you are diving to 300 feet on a CCR. That is, no one is paying you to do it, so you are just doing it for fun.

In common usage, on the other hand, people say “recreational” when they mean a dive without mandatory staged decompression stops. So depending on your definitions, this dive could be considered recreational or not.

In order to accomplish a dive on CCR, the gas mixture must be carefully calculated, and most likely includes the use of helium in the mixture (to preclude nitrogen narcosis) and reduced oxygen levels. These levels of oxygen must be automatically increased, or a switch made to alternate gas supplies, when surfacing if my understanding of diver physiology is correct (docs, help me out here).

A CCR works by circulating a single breath for most of the dive, and removing the CO2 that your body generates. There are two small tanks - one maintains a set PPO2 by adding O2 at a rate sufficient to match what the diver metabolizes. The other adds a diluent - air or some other gas - to maintain the loop volume as you descend and ambient pressure increases. Diluent can contain helium for deeper dives, to keep the END in an acceptable range, but it isn't added continually once you are at depth.

When you ascend on CCR, ambient pressure drops and so does your PO2. This is one of the challenges of diving a rebreather, and a fast ascent from depth can indeed result in hypoxia, so O2 is added to the loop on ascent.

In doing an emergency swimming ascent from 300 feet, would the CCR be able to change the oxygen level fast enough to sustain consciousness?

In an emergency swimming ascent (CESA), I believe that the diving equipment is irrelevant - OC or CCR. It is no longer supplying gas to the diver. The ascent results in gas continually venting from the lungs, so the only FIO2 that is in the equation is what was in your lungs when you started the ascent.