Ca't access my shears...????

[Divesherpa]

The reason Controlled Emergency Swimming Ascents are still taught is because most body recoveries are done on people who didn't remove weights, which would have kept them alive (recreational).

 

[Scuba446]

"If you have a catastrophic failure which renders you without gas, your buddy should be able to lift you and then make you buoyant at the surface."

I'm not talking about gear failures, I'm talking about a super-serious scenario - such as accidently swallowing water or inhaling such..

 

[Scuba446]

rcohn,
Read that article, but that was with special suits, not normal 'recreational' scuba gear - meaning wetsuits...

Which leads me to my next question - if one DOES continue to breathe during ascent normally, would you still get an embolism?

Probably most likely, huh, if one missed their Safety Stop or Deco Stops?

I would think CERTAINLY if one misses their deco stops, your gonna bet bent and/or wind up with an embloism.

 

[Rick Murchison]

Scuba446 once bubbled...
Which leads me to my next question - if one DOES continue to breathe during ascent normally, would you still get an embolism?
Probably most likely, huh, if one missed their Safety Stop or Deco Stops?

NO!
Embolism is an overexpansion injury, the result of trapped air in the lungs (holding your breath) expanding beyond the capacity of the lungs during ascent. As long as you maintain an open airway (breathe continuously) you can handle any ascent rate you can achieve on scuba (drop your weights and inflate your BC and swim for the surface as hard as you can) without danger of embolism.
---------------------
Arguments for making the weightbelt hard to jettison for recreational divers are overblown, and statistics of diver deaths support a conclusion that we as an industry are remiss in not adequately teaching how to do it quickly, easily and in a timely fashion. And not only do you need to be able to jettison enough weight to achieve positive buoyancy quickly and easily, you need to have that jettisonable weight arranged in one of the several standardized fashions that a rescuer can do so with automatic ease. The key to safe weightbelt management is to distribute weight in a way that you can swim down with an accidental loss of your jettisonable weight, not whether you can swim up with all your weight firmly attached (you should be able to do that, but that's a different issue).
I for one am firmly opposed to any gear arrangement for open water that has no provision for the quick, easy, automatic even in a panic situation jettisoning of enough weight to achieve positive buoyancy - it doesn't have to be much (at depth you should be neutrally buoyant as a matter of course, so any jettisoned weight will start you up), but is should be enough to achieve positive buoyancy at the surface with a fully deflated BC or a flooded drysuit (if you're OOA and have a failed BC and a flooded drysuit it just ain't your day).
DIRW (doing it Rick's way) dictates a weight system that your average OW diver can jettison quickly and easily when they come to help you.
How much is enough but not too much jettisonable weight? Depends on your gear, but usually 6 to 10 pounds. If you need more than that in jettisonable weight to float at the surface you might want to have a serious look at changing your gear configuration.
Rick

 

[rcohn]

Rick Murchison once bubbled...

NO!
Embolism is an overexpansion injury, the result of trapped air in the lungs (holding your breath) expanding beyond the capacity of the lungs during ascent. As long as you maintain an open airway (breathe continuously) you can handle any ascent rate you can achieve on scuba (drop your weights and inflate your BC and swim for the surface as hard as you can) without danger of embolism.

I just want to note this assumes healthy lungs and no mistakes when keeping the airway open.

Rick Murchison once bubbled...
The key to safe weightbelt management is to distribute weight in a way that you can swim down with an accidental loss of your jettisonable weight, not whether you can swim up with all your weight firmly attached (you should be able to do that, but that's a different issue).

........

How much is enough but not too much jettisonable weight? Depends on your gear, but usually 6 to 10 pounds. If you need more than that in jettisonable weight to float at the surface you might want to have a serious look at changing your gear configuration.
Rick

I agree with the comments about easily and reliably ditchable weight for a recreational diver. One of the great fallacies propagated on the Internet is the ridiculous claim that the safest way to dive in a cave is obviously the safest way to conduct a shallow recreational reef dive. The needs are very different, the bailout options are different (rec divers can ascend directly to the surface) and the gear and training should reflect these differences.

Keeping only 6 to 10 lb ditchable may work well for warm water divers, but is much more difficult for cold water divers. My habit is to keep my freediving weight on my weight belt and the rest fixed to the tank. The real problem I see is the terrible design of weight belt buckles, much to easy to accidentally release. If the belts were more reliable, accidental ditching would be a minimal concern. Some of the new integrated weight releases are more secure, its time to do the same for weight belts.


Ralph

 

[Cave Diver]

rcohn once bubbled...
3. Whether the US Navy still does the training is irrelevant, a rapid ascent is still possible. I believe the US Navy still carries escape gear and the British still do the training. Even it everyone immediately ceased all rapid escapes, thousands of training dives and a few actual escapes were done in the past.

One of those references you cited states "Diver, please not this is NOT an acceptable ascent rate." In my (possibly skewed opinion) they are stating that just because someone escaping from a submarine could possibly survive an ascent rate like that, I diver will not. Lung overexpansion is not the only reason for slow ascent rates when breathing compressed air. Sure you might be able to exhale, but what about that nitrogen bubble that comes out of solution as you rocket to the surface.

Thanks for providing the links tho, it answered my question (because it seemed as if it did not refer to divers at all) and provided some interesting reading.

 

[rcohn]

I'll try one more time.

Some ill-informed divers seem to believe that a rapid ascent because of lost weights or whatever will almost certainly result in embolism and death. The extremely rapid ascents used by various navies PROVES this to be completely false. Relax and breath or continuously exhale and you will be ok. This is the only point I’m trying to make. IN ABSOLUTELY NO WAY AM I SUGGESTING THAT RAPID ASCENTS ARE A GOOD OR SAFE PRACTICE.

Bends are a different story of course. For a recreational diver, a rapid ascent may lead to the bends. However, if you are within the NDLs the odds fall very strongly in your favor that it will not. For a technical diver with a large deco obligation the bends may quickly lead to death as in “The Last Dive.”

While you may point out that this is the tech diving section, Spectre who started this tangent, is not a technical diver and has no risk of death from explosive decompression.

Ralph

 

[Scuba446]

OK, thanks...

 

[Spectre]

rcohn once bubbled...
1. No one is recommending dumping the weight belt, the question is will you almost certainly die if it happens.
[...]
It comes down to proper training and education, a subject on which many people on this board love to pontificate. Very rapid ascents are possible if you breathe normally or exhale continuously and relax. If you believe that you are going to die you will be in a panic, where the natural reaction is to hold your breath. If you panic and hold your breath, you will embolize and may die.

Ok... just a little clarification. First off... I give instructions to my buddies on how to release my weight belt. That obviously implies that I condone it. I like to make it clear that it should be done as an absolute last resort.

It sounds like your skills need work.

This... I feel is an un-called for comment. You've never dove with me, so you have no basis to make claims on my skills. If _I_ am dumping my weight belt, I am/will be completely aware of my situation. If my buddy is dumping my weight belt, skills won't make any difference, as I won't be in any position to draw on any skills [e.g. unconcious].

One more thing. You definately don't know me very well. One of the driving forces in my survival skills is accepting the worst. If I believe there is a high probablily of my injury or death, I accept it, and move on with my full focus on doing what I need to do to survive.

Spectre who started this tangent, is not a technical diver and has no risk of death from explosive decompression.

no risk from explosive decompression... *sigh* Chatting with me at the bar a couple of times does not make you an expert on me, my dive profiles, nor my personal physiology. If you would like to dispute comments I make, please dispute them with facts, and not assumptions.

 

[Spectre]

rcohn once preached...
2. Whether it’s 1 second or many hours at depth, the risk of embolism is the same, which I assume (hope) is why Jeff thinks he will die.

Ok... I guess I wasn't done with my replies. Please point out where I said _anything_ about embolisms as a result of ditching a weight belt. If it was an embolism I was worried about, I wouldn't condone dumping my weight belt at all, and I wouldn't have mentioned that I have been working on finding ways to distribute my weight enough to have a weight belt that would be safely ditchable.

I'm _not_ referring to embolisms, I'm referring to uncontrolled rocket ascents and _everything_ that would come into play in that sense.

Now I'd like to see your proof that it is impossible to receive a fatal DCS hit when ascending from 130 fsw at the edge of NDL limits.