Accident analysis

[Summer06]

Hi Paul,

First of all, thank you for your post. This is exactly the reason why I like coming to this forum...the opportunity to learn from other divers like you. The only thing that I think you could have done a little different was not to leave your buddy...but you already know that. Again, thank you for sharing your experience as a learning tool for the rest of us.

 

[paulthenurse]

From these 2 statements it seems that AD buoyancy was nearly neutral, probably slightly positive, when he swam over to Paul, descending a few feet allowed him to hover, not do a handstand which occurs if you are pounds light.

The only change to his weighting is the air that he is breathing, which, as he is calm, would be insignificant over a 5 minute period.
He ascends a few feet and he is into a runaway ascent.

This can only happen if either he has lost weight, or he has gained volume. Now as the only weight he is loosing is the air he is breathing then he must have gained volume.

I think you missed the part about AD swimming over and grabbing ahold of my manifold. If he was light (with or without any extra air in his suit/wing) he would have been able to hold himself down easily by holding on to me. (I'm a lardass and weighted to stay belly to the bottom.) It was only when I unknowingly pulled the manifold out of his grip that he went into his ascent.

 

[victor]

Paul
Sorry, almost wish I had not started this. As I have said before no one did anything wrong here and I would happily dive with any of you.

What I don't understand is what happened in the few seconds between

AD swimming over and grabbing ahold of my manifold

when he was heavy enough to swim comfortably to you and

pulled the manifold out of his grip that he went into his ascent

he was so buoyant that he went into an uncontrolled ascent.

The only weight change in that time was a few lungfulls of air.
Therefore it must have been a volume change.

One posibility is that while he was holding your manifold you were both ascending from 30ft to say 20ft. That would allow the trapped air in his drysuit to expand by 33%.
Another posibility is the inflator on his drysuit was leaking slowly and adding air.

Something must have changed either weight, volume, or a tractor beam from the startship enterprise.
Personally I like the tractor beam theory.

:thinkingo

 

[paulthenurse]

Paul

Something must have changed either weight, volume, or a tractor beam from the startship enterprise.
Personally I like the tractor beam theory.

:thinkingo

Ya know, it's the 'Outside the Box' thinking, like the 'Tractor Beam Theory,' that made all the typing worth while!

I'll leave it to AD to describe in his own words what happened. Obviously I won't be able to give a cogent explaination for HOW something happened when I wasn't even aware it WAS happening.

 

[ArcticDiver]

Hadn't thought of the Tractor Beam From Space factor. THAT very neatly explains it all, eh?

Actually, when I swam to PTN I was approaching from below his level. I was already headed up. But, because he was a good buddy, we were very close to one another and I was able to stretch out and grab his manifold. Mind you this "uncontrolled ascent" is a very slight rate of climb.

By the time I had signaled "problem"; made sure there was no air in dry suit or wing; and he had departed with my anchor I had breathed more gas. Therefore, I was more buoyant yet.

Also, when I was with PTN I was above him. So, when the "anchor" left going down to look for Len I left for the surface.

Lets talk about that "uncontrolled ascent" for a moment. From your comments Victor I get the impression you are picturing a rocket like ascent with me not being strong enough to get my feet down to vent the dry suit, or to be able to vent the wing.

First this was not a rocket. I didn't broach like a whale or a submarine. Weighting was close enough, as we have posted, that it would more properly be called an "undesired ascent". Or, like TS&M posted "going light". I caught the problem early enough that there wasn't a huge buoyancy differential.

Next, as we have posted I did, indeed, get all the air out of my gear before PTN departed. Sure, like everyone else, there are things I'm just not strong enough to do. Rotating in the water to get the proper body position isn't one of them. Doing flies with 100# dumbbells like the guy next to me in the gym yesterday is.

 

[TheRedHead]

It's a lot easier to prevent an undesired ascent in a typical 3/2 wetsuit than with drysuit unders which are very bouyant. ArticDiver, were you wearing a neoprene drysuit?

 

[ArcticDiver]

It's a lot easier to prevent an undesired ascent in a typical 3/2 wetsuit than with drysuit unders which are very bouyant. ArticDiver, were you wearing a neoprene drysuit?

Read previous post about under garment. The suit is not neoprene.

Gee, I wonder what about Paul's posts and mine that are not clear about why this happened? After getting the best advise available I made a small, but incorrect, weighting decision that didn't manifest itself until the gas supply was breathed down on the second dive. Paul and I got our wires crossed on our actions once the problem was discovered. What is so difficult to understand about that?

Folks, we didn't post this for anyone to do cyber-detective work on the causes. We know the causes. Both Paul and I made mistakes. We 'fessed up to them for everyone's benefit because both of our experiences show that it is better to learn from others' mistakes than our own. Such is the base of all good incident analysis and education.

I'm starting to get the feeling that the old adage; "No Good Deed Goes Unpunished" is actually true

 

[victor]

I am still putting my money on the enterprises tractor beam.
:lol:

 

[mikerault]

And gee, a remote signalling device like the dive buddy pinger I proposed would have allowed you to alert Lou and head up without leaving the troubled buddy.

Mike

 

[TheRedHead]

Read previous post about under garment. The suit is not neoprene.

You wrote the water was 47 F. You must be crazy!

I've been able to stop a cork from too little weight by remaining heads down and kicking for 3 minutes. Once you go vertical it's all over. I don't see your incident as being serious at all and hope I can continue to dive and retire about a liveaboard.