Diving too carefully?

rjack said:
I know of two single tank deaths both at 50+m. One is bad hit (was on doubles but passed out due to narcosis and blew off a bunch of deco). He's now partially blind and on permanent disability. In the last ~7yrs.

I wouldn't know how many quit (at least a few I'm aware of), other than the disabled guy who enjoyed his solo narcosis dives, most of the local deep air folks are not contributors to boards like this. They tend to do the same shore site repeatedly, but may or may not have any deco training at all.
Click to expand...

Bizarre stance towards a largely forgotten pursuit for tech diving... but pre-naughties we didn't have much choice.
Diving to 50mtrs on a single is well within the training and practice of many organisations "back in the day" although now frowned upon. I have done several 60mtr single tank air bounce then up the reef dives on Holidays, I know hundreds who have and a dive centre owner who's customers do it daily- its not big or clever but its not impossibly dangerous as you make it out to be- remember before mix-gas we had no choice.


Michael Thornton said:
Are the cases of bends increasing or is the reporting of them just getting better?
Click to expand...

I'd speculate that their are less bends per dive as time goes on and that the reporting is now far superior.

Even a decade ago skippers here turned a blind eye to divers sucking their 80% dry on the boat ride home and having a cheeky 100% cylinder in the car for the drive home- Yes, I have actually seen this. These days if you even twitch coming up the lift or ladder you have O2 stuffed in your mouth and the chopper overhead.
 
Ben Field said:
Bizarre stance towards a largely forgotten pursuit for tech diving... but pre-naughties we didn't have much choice.
Diving to 50mtrs on a single is well within the training and practice of many organisations "back in the day" although now frowned upon. I have done several 60mtr single tank air bounce then up the reef dives on Holidays, I know hundreds who have and a dive centre owner who's customers do it daily- its not big or clever but its not impossibly dangerous as you make it out to be- remember before mix-gas we had no choice.
Click to expand...

I'm not saying its necessarily the worst thing. But few people did dives this deep, in cold water, with high currents and quite a bit of dark narc contribution back 20 or 30 yrs ago. The divers doing those dives existed sure, were they widespread I don't know. Until recently some of our most serious wrecks dives you could count the numbers of unique divers on them with a few hands. How many people are doing 60m dives in the Channel on air today?

But the recently injured people I mentioned often have little or no training and most of them are doing it for "the rush" - not even to see anything in particular. Probably influences their track record, although the now partially blind guy was doing solo "deep" air (50-60m) dives for quite a few years before he passed out.
 
rossh said:
Now, in order to make significant VGE, one needs a significant gas supply to make it from, that resides in the tissues. Then it needs to be removed from tissue, converted to VGE quickly and in large volumes.

To achieve that you need a big dive with fast deco. Or one could take a normal dive, and drive gas out fast under extreme conditions like SurD or direct ascent. Or one could do a really deep dive and surface with significant gas to off load, and drive it out by exertion.


But the victim did not do any of those procedures or conditions. He did a normal small deco dive, a normal easy deco ascent, and promptly dropped dead. Nothing of his dive procedure was capable of making an extra large dose of VGE.

As they say "you cannot make strawberry jam from dog pooh". The ingredients of "massive VGE" were not there.


*****

Lets examine the other side:

Now if you wanted to say something like - he had normal gas loads, normal VGE levels, but a failing respiratory system that was not function fully, and finally give up at the end of this dive - I'd believe you. Under this situation, his lungs are not performing as expected, and the accumulation of VGE overwhelms him. Is such a thing possible?


****

The basic difference between these two explanations:

The first implies extraordinary volumes of VGE and dissolved gas are in motion, in a healthy individual.

The second implies that normal levels of gas and VGE are in motion, but the individual is suffering from a weak or failing respiratory system, that eventually cause his death under the added stress of normal decompression.
Click to expand...

Just so I'm clear, rossh, are you saying that in order to get DCS one needs to either have an ascent rate violation, other omitted decompression, exertion, or bad lungs? That without the first three a large VGE load can't form, and if there is a 'normal' VGE load the healthy lungs should deal with it?

If so, then that seems a very, very small step away from saying that 'divers who follow the rules can't get bent'. (Not intending to put words into your mouth but one COULD interpret your comments that way).

Is that what you believe?

Deralie
 
deralie said:
Just so I'm clear, rossh, are you saying that in order to get DCS one needs to either have an ascent rate violation, other omitted decompression, exertion, or bad lungs? That without the first three a large VGE load can't form, and if there is a 'normal' VGE load the healthy lungs should deal with it?
Deralie
Click to expand...

No.


Simon proposed that this man died from "Massive VGE". However, he fails to explain where or how the extra supply of inert gas came from, to make this extra large and extraordinary load of VGE. I gave some examples above of how to get massive VGE that cause death, but none of these apply to this mans situation. In Simon's theory of this mans death, the question remains unanswered as to this source of extra large volume of gas.



deralie said:
If so, then that seems a very, very small step away from saying that 'divers who follow the rules can't get bent'. (Not intending to put words into your mouth but one COULD interpret your comments that way).
Is that what you believe?
Deralie
Click to expand...

No. Quite the opposite in fact.

The deco plan is only a small part of the overall components of decompression stress and risk. There are many pieces that make up the total decompression stress, including preparation, procedure, health status, to name a few. A failure of any of these can turn a good dive into a bad one. Procedure and health failures are regular causes of injury, even when following the plan..
 
rjack said:
How many people are doing 60m dives in the Channel on air today?
Click to expand...
A lot more than you would care to imagine.

A good mate died 5 or 6 years ago doing just that. I still believe he was peer-pressured, by old blokes he looked-up to and respected, into believing that real men dive air and that trimix was for poofters.
 
I had mix in my unit from my third dive. I cant imagine using air ever unless I was stuck in the arse end of nowhere. I think every time I've used air dil I've cocked something up.
 
I will be having mix from the start too, but I wouldn't be confident jumping in on a 60m dive straight away.

In answer to your question Nick, maybe nothing. But potentially lots!

Regards
 
GLOC said:
Anywhere between £55 and £80 for twin 12s of 18/45 at the moment!
Click to expand...

Holy cr*p! Only if you are buying it direct from somewhere super cheap, down on the coast you're looking at £120-£180 for a twinset and deco bottles of the funny stuff!

GLOC said:
I will be having mix from the start too
Click to expand...

No, you won't- you'd be Farm Animal level stupid to dive Mix dil at 6-20mtrs (which is what your early CCR dives will be) even down close to 40mtrs you are streets ahead safer/cheaper on Air dil (aka- Nitrox diving)

Ignore the internet warriors- on CCR Air dil is perfectly usable and the money saved pays for slime for more dives.
 
Ben Field said:
Holy cr*p! Only if you are buying it direct from somewhere super cheap, down on the coast you're looking at £120-£180 for a twinset and deco bottles of the funny stuff!



No, you won't- you'd be Farm Animal level stupid to dive Mix dil at 6-20mtrs (which is what your early CCR dives will be) even down close to 40mtrs you are streets ahead safer/cheaper on Air dil (aka- Nitrox diving)

Ignore the internet warriors- on CCR Air dil is perfectly usable and the money saved pays for slime for more dives.
Click to expand...

Well said. I second that. Air-dil just fine for the shallow stuff. It is nitrox so what?
 
Ben Field said:
No, you won't- you'd be Farm Animal level stupid to dive Mix dil at 6-20mtrs (which is what your early CCR dives will be) even down close to 40mtrs you are streets ahead safer/cheaper on Air dil (aka- Nitrox diving)
Click to expand...

Safer? So is helium "dangerous" again too?

Peter L said:
There is a lot to be gained keeping your EAD shallower than 29m / 95' from a work of breathing / retained CO2 perspective.
That's my cut over point.
Click to expand...

My shallow dil bottle is roughly 18/25. Using that to about 35-40m depending on what I have for bailout (usually air). Deeper than that I bring a different dil tank.
 
Last edited:
You must log in or register to reply here.
Back
Top