DumpsterDiver emergency ascent from 180'

[2airishuman]

Really? How about shutting down the free flowing post and still having access to all of the gas not lost in a free flow?

In this situation, manifolded isolatable doubles would have been a much better option than losing ALL of his backgas. Even with tiny doubles(45's) he would have had a huge redundancy advantage.

We were discussing a comparison among H valves, Y valves, and doubles. Any of them would permit a shutdown of the freeflowing post.

 

[Diver0001]

If he was diving with a buddy would it be acceptable for him to share the reserve with another diver? So in that case if both he and his buddy had 20cf ponies would that be enough as the total would be then 40cf?

Almost all recreational divers and most technical divers routinely plan for this, whether they are aware of it or not. You can see it like this: My buddy is carrying MY backup.....

It is part of the reason that 3 person teams are popular in a technical context. There is a lot of flexibility to be had there..... The risk, of course, is that one or both of your buddies will be lost/unavailable when you need it most. A buddy separation then goes from being "inconvenient" to being "threatening".

R..

 

[tomfcrist]

We were discussing a comparison among H valves, Y valves, and doubles. Any of them would permit a shutdown of the freeflowing post.

I get that. But which one offers the most overall redundancy? Especially if you dive the isolation valve cracked open vise full throw. It takes two seconds to reach back and isolate to save 1/2 of your gas supply. If you shut the free flow post down quick enough after that...you now have access to alll the gas in both tanks.

H and Y valves have their place, but they have severe limitations. The biggest being they can be a pain to shutdown quickly. Especially the bechaut Y valves...if only because the knobs are in an inconvenient position. Is it better than a standard single outlet valve? Sure. Is a set of manifolded isolatable doubles better yet? Of course.

The reality is, that this dive was done in a way that in no way would pass any sort of risk management analysis...at least not for someone who isn't willing to sacrifice risk mitigation for laziness or ease.

 

[HantsDiver]

Almost all recreational divers and most technical divers routinely plan for this, whether they are aware of it or not. You can see it like this: My buddy is carrying MY backup.....

It is part of the reason that 3 person teams are popular in a technical context. There is a lot of flexibility to be had there..... The risk, of course, is that one or both of your buddies will be lost/unavailable when you need it most. A buddy separation then goes from being "inconvenient" to being "threatening".

R..

I asked the question because there seems to be an awful lot of comments relating to the size of the pony/bailout. In a solo context that is valid.

However - advanced rebreather divers share bailout. I share my OC deco bailout reserve (if I drop a stage I will share my buddies). And obviously for most recreational diving people use an alternate as a bailout.

I think you'd have to very unlucky to both lose your buddy - and have a catastrophic gas loss at the same time. It's certainly not something I'd worry about when doing a technical dive.

 

[oldschoolto]

He should have had a submersible sub... With a support ship... And we could add in some safety divers and a chamber too... Okay, sarcasm off... You guy's would die down there... You are way over thinking it.. You don't play around, You go... I'm guessing , because I don't know him.. It went some thing like this... Mass air leak behind his head... Time for me to go... Adds some air to bc so it's a free assent ( No swimming ) and no extra air needed to fuel the body... keeps the assent rate in check to not cork... Shoots off his SMB and swaps to his pony when the back gas goes... Blows off any safety stop because he never went in to DECO and the SMB was in mono-filament line and felt safer up top...

Jim....

 

[Altamira]

While one can condone or condemn DD's diving style, his posts, and posts made by others, describing his diving issues, one thing is certain: They sure do elicit some very educational and entertaining discussions on SB.

 

[scubadada]

Interesting how the dD post, without dD, is one of the most active threads on SB, with 176 posts in just in 2 1/2 days.Interesting topic to many divers

 

[stuartv]

You're talking about feathering the broken valve. If it were a stage bottle then you could get at it easily. In a singles configuration feathering the valve is very tiring and usually takes both hands. I don't know if you've ever tried it but I did during my technical training and my arm was seized up to the point of not having the strength to turn the handle before long. Don't forget that you can't just open the valve a little bit at that depth and expect to get enough air. At that depth feathering would require turning hard and fast on the valve in both directions for each breath in order to compensate for the effects of ambient pressure. You can't just crack it open and breathe like you would, for example, in a swimming pool. The pressure makes that impossible at those depths. If he were shallow it might have been an option.

I'm not sure you really read what I wrote. I specifically said to shut down the valve completely and leave it shut until such time as the pony ran dry. Unless you shut it down and it was still dumping. In which case, open it again and use it exactly as he actually did.

Feathering (as I described) would only happen if your pony ran out. Thus, you would be shallow.

 

[Boaty McBoatface]

Is the reason that people are particularly fond of al40s as bailout/deco bottles (apart from their volume and general size) that they tend to float horizontal, their total buoyancy (empty/full), or is it something else?
Thx

 

[CuzzA]

He should have had a submersible sub... With a support ship... And we could add in some safety divers and a chamber too... Okay, sarcasm off... You guy's would die down there... You are way over thinking it.. You don't play around, You go... I'm guessing , because I don't know him.. It went some thing like this... Mass air leak behind his head... Time for me to go... Adds some air to bc so it's a free assent ( No swimming ) and no extra air needed to fuel the body... keeps the assent rate in check to not cork... Shoots off his SMB and swaps to his pony when then back gas goes... Blows off any safety stop because he never went in to DECO and the SMB was in mono-filament line and felt safer up top...

Jim....

Dude you hit the nail on the head. Pretty much textbook, right?

Let's add a little context... He was fishing too (Some of us catch our fish in the cleanest way possible, no mono, no hooks, no fish markets... earn what you eat), streamlining is a factor. Too much is dangerous. There's sharks following... Half the people who have participated in this thread would likely be dead from this incident regardless of the minutiae or how big their pony was. My basis is only one person who has responded has reported a complete scuba failure...

My point is he didn't survive by luck. He reacted. So, to add another takeaway from this thread... think about what just happened on your dive... boom... what's your next move? We should all have the answer, right?