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

[Protondecay123]

Hey John.

Most any CCR will have multiple redundant readouts of the (multiple, redundant) O2 sensors in the loop. These often take the form of Shearwater handsets or similar, and very often there is a HUD and/or other alerting mechanism.

My unit, the Poseidon, has a handset, vibration unit and HUD combination, audio alarm and a big flashing light on the back to tell my buddy if I missed all these other warning signs.

The problem is usually a sensor issue rather than a diver/machine interface problem.

Does it have a sensor for elevated CO2 levels or some other way to detect hypercapnia?

 

[dmaziuk]

For CO2 we have a built-in one, though I've no idea what happens to it at those pressures.

 

[Caveeagle]

--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).

Strict definitions usually fall apart at some point. There are caves where you can easily do 2,000 ft linear penetration with no deco, and most would still consider in the realm of “Tech”. The term “Technical diving” has only been around since the early 90’s, so.....

RainPilot,

What features of CCR will warn the diver of PPO2 drop, other than a blackout? PPO2 drop physiologically has no warning. Again, going to the DeJoy diagram, what are the Person (Diver) Machine Communications that would indicate such a failure? If a diver is preoccupied by environmental factors, can this communication overcome the distraction?

SeaRat

Several redundant indicators for PO2. I am much more concerned about Co2.

 

[beester]

Just a noob CCR diver (less than 50 dives) but quite a lot of full trimix experience (GUE T2+, still diving OC to 250-300ft to this day). Any input on gasses used (WOB) and temp at depth?

I can imagine that at that possible cold temp, and depth that scrubber duration, breakthrough, hypercapnia due to WOB, are significant factors to be considered.

In any case I'm sure that we'll never get to the bottom of this, because the main actors who could shed light on the issue are no longer with us.

Also to the family, friends and relatives.... I deeply feel for you.

 

[Marie13]

Temps would probably be 37F ish.

 

[NAUI Wowie]

Exactly and I literally GROAN every time someone inevitably says "was it a rebreather"... it's exactly as productive as reading a thread about a 250kph motorbike crash and asking if it was a 1000cc sports bike, before telling everyone how much more dangerous those things are than scooters.

I would pick my Fireblade over ANY scooter at 250kph. At nearly 100m - the limit of OC Advanced Trimix - this was a 250kph dive.

you show me a scooter doing 250kph and ill show you a safe rebreather working at the bottom of the marianas trench....

not to derail the discussion

 

[NAUI Wowie]

Just a noob CCR diver (less than 50 dives) but quite a lot of full trimix experience (GUE T2+, still diving OC to 250-300ft to this day). Any input on gasses used (WOB) and temp at depth?

I can imagine that at that possible cold temp, and depth that scrubber duration, breakthrough, hypercapnia due to WOB, are significant factors to be considered.

In any case I'm sure that we'll never get to the bottom of this, because the main actors who could shed light on the issue are no longer with us.

Also to the family, friends and relatives.... I deeply feel for you.

personal curiosity, why do you continue to trimix OC dive 250 to 300 ft deep? Is it to reach specific wrecks? And do you prefer OC at those depths for ease of use compared to rebreather, or another question do you prefer rebreather but sometimes do OC to dive the same as dive partners?

 

[rjack321]

I can imagine that at that possible cold temp, and depth that scrubber duration, breakthrough, hypercapnia due to WOB, are significant factors to be considered.

While stranger things have happened, it seems rather unlikely that they wouldn't start a dive of this magnitude with fresh scrubbers. But they could have been repacked with dubious sorb? (since it doesn't really expire per se this is also unlikely). Or perhaps all 4 scrubber were hastily packed by one of them and it settled? (in all four canisters that again seems unlikely)

On the other hand, contaminated gas is always a worry on a dual fatality like this.

 

[2airishuman]

According to a local report, they were both using scooters. Fwiw, quite possibly nothing to do with anything.

 

[Marie13]

According to a local report, they were both using scooters. Fwiw, quite possibly nothing to do with anything.

There are videos Jim Winn posted online on both the Emba and Thomas Hume wrecks in late May/early June that show the scooters.