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

[cerich]

For the record, I never looked forward to ever having to use the escape trunk. Didn't sound like a solid escape plan to me at most operating depths.

Well..we used to joke that we had escape towers so we could reassure wives and parents...that said having once having to shut the bulkhead down during a real flood from the flooding side in a compartment that didn't have one made me wish it did

 

[HKGuns]

Well..we used to joke that we had escape towers so we could reassure wives and parents...that said having once having to shut the bulkhead down during a real flood from the flooding side in a compartment that didn't have one made me wish it did

Yikes, yeah that would certainly adjust your attitude. It wasn't flooding in the goat locker was it? Sounds like it turned out well for you........

Worst I had was fire in AMR2 while on station.

 

[uwxplorer]

To reiterate, this is not a condemnation or criticism of either unit, but an attempt to explain why people say that the rEvo sinks when flooded.

I didn't take it like this and although I am using it, you will never see me raving about it. It has its limitations like each unit.
One which I have not been able to verify myself (and might never if I follow my current evaluation of the associated risks and my own limitations) is that it becomes hard to breath at the kind of depth they were using it at. They had scooters, which alleviate some of the issues associated with high WOB, but it's a very hostile environment down there.
For what it's worth, my impression is this tragic accident may be a rescue attempt run horribly (and predictably) wrong.

 

[cathal]

Worth bearing in mind how the necessary dwell time for the scrubber to work will be adversely affected with depth and effort. Both of these factors are relevant in this tragedy.

 

[John C. Ratliff]

As a long-time diver, but never a CCR diver, I have learned a lot from this thread. My thanks to everyone who contributed here.

SeaRat

 

[DOBY]

Worth bearing in mind how the necessary dwell time for the scrubber to work will be adversely affected with depth and effort. Both of these factors are relevant in this tragedy.

The relationship between scrubber dwell time and depth and/or exertion are well known. How is the above specifically relevant to this accident, beside it being a 300 foot dive? Do you have specific information the rest of us don’t have access too how dwell time had a cause in this accident?

 

[telemonster]

I'm sure it's all speculation. It seems rare any real answers ever come out about any of the CCR incidents.

As someone else pointed out, large potential there is video footage which could shed some light. But community as a whole might never be included on any findings.

 

[TrimixToo]

I'm sure it's all speculation. It seems rare any real answers ever come out about any of the CCR incidents.

As someone else pointed out, large potential there is video footage which could shed some light. But community as a whole might never be included on any findings.

Real answers rarely surface, so to speak, for many incidents. "Why" is a complex question. Legal liability is often blamed but I'm not sure how often it actually matters. Another reason is that making a diver's failings public, particularly when there is no lesson to be learned from them, is hurtful for family and friends. Still another frequent reason is that sometimes, nobody actually knows what happened.

 

[cathal]

The relationship between scrubber dwell time and depth and/or exertion are well known. How is the above specifically relevant to this accident, beside it being a 300 foot dive? Do you have specific information the rest of us don’t have access too how dwell time had a cause in this accident?

No I do not have specific information regarding this incident, just highlighting relevant interconnected factors.

 

[beester]

It's been an interesting discussion so far. I think all experienced full trimix divers, know that unless it's a bounce dive, CESA is out of the question.

Does that mean that it can never happen.. no for sure not, maybe it evolved from a very agressive (but still in control) ascend into a full blown out of control ascend or CESA, maybe the incident evolved into a full blown panick, where clear thinking was no longer possible and the only driving factor was "I want out know" without thinking about the consequences, resulting in punching out and going like a polaris rocket to the surface.

Also I've been lucky enough never to have witnessed a full blown emergency ascend from 300ft skipping let's say 2 hours of deco. What I have witnessed from (unfortunately) very close by, is someone skipping about 1 hour worth of O² deco. This from a 90 m (290ft) dive with a 30 min BT. This skipping of deco was at the 6m (O²) stop. He survived without any ill consequences, without even having to go to a decompression chamber. However I'm also very sure that in this profile with a first deco gas switch at 57m (almost 200ft) if he would have ascended like a polaris rocket to the surface at that depth, or even shallower (let's say at the 3' stops at 36m) he would never have survived.

What would I do... well it's all hypothetical... I don't have enough CCR experience to make any valid comment, but the nefarious thing is according to me that you can solve much more issues with the rebreather down deep than with OC which is much more black and white. So a scenario were you have to go permanently of the loop and suddenly don't have a lot of time anymore to solve issues would be IMO one of 2 things... or a total flood/breakdown of the unit or hypercapnia. If I would go of the loop with still all my senses (so no hypercapnia) I would bailout and make an aggressive controlled ascend, skipping the deep deco stops, and start slowing down shallow. If I'm hit with hypercapnia, I'm not sure I would be able to bailout, and if I did I probably would not be thinking clear. In this scenario I can see an out of control ascend as a real possibility.