Pony bottle skills

[Web Monkey]

So I have a question for the tech divers posting on this thread--why don't you demand that all dive operators who allow decompression diving off their boats have a recompression chamber on-board? It would save a lot of lives if this were a requirement, and perhaps several books would not now be in print which give diving a very bad name in the public's eye(The Last Dive by Bernie Chowdhury comes to mind).

Because they're heavy, expensive and take up space, require regular maintainance and a qualified operator, and would make dives hugely expensive?

Terry

 

[jonnythan]

Can you imagine how expensive it would be to put a recompression chamber on a boat, and have trained staff sit on the boat every time it goes out? Geez. No one would dive.

 

[lamont]

Definitely agreed. The twitchy word here being, 'attentive', IMO.

yup, i threw that word in there for a reason.

What kind of failure can cause an immediate out-of-air situation, and how often does it occur? Not trying to make any particular point; I really am asking. I once saw a fairly spectacular yoke valve O-ring failure, but fairly early in the dive and the diver still had time to do a reasonable safety stop. In 12 years of diving, that's all I ever saw.

I don't think I've ever heard of another OOA event that wasn't caused by gas mismanagement. (Talking rec diving here, of course.) And if they're gonna mismanage their gas, who can say they'll be able to use their redundant gear properly? Or know which way to go to find the surface?

Anyone know are there any stats on OOA's not caused by gas mismanagement?

Probably the most likely one would be IP creep in the first stage leading to an uncontrollable free flow out the second stage. It isn't going to lose you all your gas at once, and you might be able to feather the valve to control it. One that would really suck would be losing all your gas through the HP hose to your SPG. Someone (Curt Bowen?) posted some timing tests of how long it took to lose your gas through different failure modes, none of them are immediate, but i don't think any of them allowed enough time for a stop... I have no idea of the stats on how often they occur, but they're definitely not unheard of, and I think they're worthwhile to have contingency plans for.

All of those are not necessarily going to cause injury under rec NDL limits, but without redundant gas all of the recovery options lack the elegance of just calmly using your redundant supply.

 

[Web Monkey]

I can't speak for other brands (never looked), but the high pressure hose on my SmartCom has a really tiny orfice in the HP fitting. Although I've never measured it, I would expect it to take a really, really long time to empty the tank.

Terry

hose to your SPG. Someone (Curt Bowen?) posted some timing tests of how long it took to lose your gas through different failure modes, none of them are immediate, but i don't think any of them allowed enough time for a stop...

 

[Tanked]

Can you imagine how expensive it would be to put a recompression chamber on a boat, and have trained staff sit on the boat every time it goes out? Geez. No one would dive.

Not to mention how much room it would take up. I'm sure alot of us have been on boats where other divers are steping all over your gear. Add a chamber to that boat and it'll be easier to put your gear on in the water.

 

[Soggy]

A failure from the HP hose is much less severe than a LP hose failure due to the sheer volume of gas that can be vented. Curt's tests showed this.

 

[Tanked]

A competant diver should be able to do a free swimming ascent without air from considerable depth. If you can do it from 30 feet, you can do it from 60 feet; if you can do it from 60 feet, you can do it from 100 feet; all you lack is the confidence to do it, as the air you need is in your lungs already (remember Boyle's Law?).

I have no doubt that I could do it, that doesn't mean I want to. I'd much rather deal with the extra tank on my back so I know I have the air. Or so I could pass it off to another diver if they run out of air.

 

[ronrosa]

A competant diver should be able to do a free swimming ascent without air from considerable depth. If you can do it from 30 feet, you can do it from 60 feet; if you can do it from 60 feet, you can do it from 100 feet; all you lack is the confidence to do it, as the air you need is in your lungs already (remember Boyle's Law?). Didn't we all swim underwater the length of a 20 yard pool in basic scuba class? That's 60 feet, and it was done for a purpose. If you can do it horizontally, you can surely do it vertically with three times the gas in your lungs at depth as on the surface.
SeaRat

With 135 dives to date, I guess you can still call me a newbie. I know what I've read and been told, but having never actually done an emergency ascent I defnitely lack the confidence as I'm sure many people do.

I believe that the air in my lungs will expand as I ascend, but it's counter intuitive. Let's see, I'm out of air, but I need to ascend slowly while exhaling slowly, keeping the balance of exhaling and ascending at a rate that I don't run out of air and I don't ascend too quickly. Oh, and don't panic.

Without actually having done it, it's a scary thought. Maybe it's something I should practice.

 

[Soggy]

Without actually having done it, it's a scary thought. Maybe it's something I should practice.

Please don't....Instead of practicing a 'skill' (if you can call it that) like this and potentially killing yourself, practice something useful like buddy skills so that you don't ever have to do this.

 

[ronrosa]

Please don't....Instead of practicing a 'skill' (if you can call it that) like this and potentially killing yourself, practice something useful like buddy skills so that you don't ever have to do this.

Let me clarify.

When I said practice, I meant with air in my tank, simulate being out of air by taking a breath and slowly exhaling while slowly ascending. After my 15' safety stop is done seems like a good time.