Diving too carefully?

[MeRodent]

I think its about time Mitchell got told and enforced to change his bad attitude to others. If this guy can't make his point without insulting others, then maybe he shouldn't be here.

Why is it that the insults I see all seem to be coming from you Ross?

If you want to be taken seriously (in particular when you make comments regarding any posters attitude) it doesn't help when you're abusive in the posts where you make the complaints.

 

[Elmi]

Why is it that the insults I see all seem to be coming from you Ross?

If you want to be taken seriously (in particular when you make comments regarding any posters attitude) it doesn't help when you're abusive in the posts where you make the complaints.

Dito

 

[Capt Morgan]

Hi Morgan,

Totally agree.

I dived the U861 (43m) a few times OC air, once on CC 20/20. Great stuff. Brilliant.
Then a couple of years ago I dived it on CC 11/67 - the dive I was supposed to use that on was canned due to weather. Wow. Just. Wow.
Deep air? You can keep it! Sure you can do it. What for? Helium is expensive, but on a rebreather it's cheap enough, and you make it back in value.

And that's without taking into account the safety aspect of having a clear head, and WOB, and CO2, and...

I do quite a bit of diving with a dive club. Mostly with the rebreather. Mostly above 25m. Dil is whatever is in the emptiest cylinder, possibly topped up with air. So it's usually mix, sometimes real mix. So what? Is it required? No. Not even necessary. Does it do any harm? No. Not even to my wallet. 20m, I'll use 20 bar from a 3L. That's what? 1 euro? 2? Pound, whatever. So why not?

Cheers,

Matthieu

Funny you should mention the U-861, I was on it a couple of weeks back
and was diving OC for the first time since getting my unit.
I was shi**ing myself as to how my head would be on the dive, the last
time I was at that depth on air was the time on CCR on my course.
As it happened I was fine so I guess it shows the OC CC difference.
I started diving over 25 years ago and nitrox was an unknown let alone
trimix , I didn't do crazy deep air but it was deep enough to know my
head was seriously fuzzy I can't think of the last time I dived air, it was
always nitrox or trimix OC and just trimix CC now.

Should people start from day one mix in diluent. From day 1 means after you finished mod 1?
I am not arguing what you are refering about, but should you be in that range of depth for the first dives on ccr on your own ? We are not talking about deep air here, imho for the beginning of ccr diving you should stay in the shallows 20m max and there i do indeed not see the need of helium. If you want go ahead, no harm.
But more importantly start your adventure ccr gradually and shallow

Good question, all I can say is that I was diving my unit before I did any courses.
It started with shallow quarry dives where I feel I was learning the basics, that I
have to say are not that hard to learn. Hardest part was not using my breath to
control buoyancy and it clicked during my first go on the unit.
I was OC trimix qualified already so knew the importance or buoyancy control etc.
When I went to do my course it was a mod1 trimix course because the training agency
took into account my OC qualification.
Should a new CCR diver after mod1 be diving trimix ? I can see both sides of the argument
but one thing is for sure, I wouldn't be going much over 30m an air in any case.

 

[Ben Field]

Safer? So is helium "dangerous" again too?

Please direct me to research on using Helium mixtures for less than 20mtrs... as far as I know most work focusses on using it deeper than 40?

It also artificially (possibly, IMVHO) messes up the output from off-the-shelf decompression computers, and the ultra thin gas at shallow depth increases risk of free flow and performance of ADV making maintaining the PPO2 harder.

IMO (not Humble this time ;-) lots of divers use helium all the time for bragging rights, "yeah just another mix dive" knocking it off casually like they've been to the Brittanic when in fact they've been watching pretty fishies at no more than 25mtrs.

Divers in general should MTFU and use the right gas for the dive, Trimix for 10mtr training dives is plain stupid, there is nothing uncool about Air Dil.

 

[Ben Field]

The prognosis given was "massive" VGE. VGE do not grow out of nothing. There has to be a gas supply to make them from. Simon described this as "massive" amounts. Where did the massive gas supply come from to make this massive event? Or did something else happen here? I cannot imagine or think of a scenario that has this man absorb double or triple the usual gas load that could explain this situation. There has to be some other explanation for this sad and unusual event. What is it I wonder? Anyone care to speculate?

Quantify "Massive" for us please? Its not an SI unit to my knowledge.

In this case is Massive- Alot, More than usual, More than could reasonably be expected or Surprisingly more than thought possible?


Perhaps the gas expanded as the victim ascended creating a Massive amount from a Usual one?

 

[Ben Field]

I hate using air diluent on any dive. I only keep trimix in my diluent bottles so should I bin that if I want to do a scallop bash at the end of the day or get asked to have a shallow dip at the local quarry? Absolute nonsense.

Topping off and using left overs is not "choosing" to use a diluent, its just basic pikyness

Choosing is Purposefully putting mix in a tank knowing you'll be doing single tank scubee stuff- that is what I was referring to as Stupid.

I'd wager that if you where invited to join the Scallop boys for a day at 10mtrs you would not bother with helium dil (or CCR in general) but I know you wouldn't purposefully waste banked Trimix on flatty bashing!

 

[nickb]

I'd wager that if you where invited to join the Scallop boys for a day at 10mtrs you would not bother with helium dil (or CCR in general) but I know you wouldn't purposefully waste banked Trimix on flatty bashing!

You would lose that wager. I ONLY use trimix diluent - end of story.

How much 'waste' are we talking about here? The sorb would cost me more than 5 times what the gas would cost me.

Divers in general should MTFU and use the right gas for the dive, Trimix for 10mtr training dives is plain stupid, there is nothing uncool about Air Dil.

And there was me thinking that telling divers to 'MTFU' ended when Irvine gave-up trolling on the internet. You've lost any credibility to had with me with that shit Ben.

 

[Elmi]

Funny you should mention the U-861, I was on it a couple of weeks back
and was diving OC for the first time since getting my unit.
I was shi**ing myself as to how my head would be on the dive, the last
time I was at that depth on air was the time on CCR on my course.
As it happened I was fine so I guess it shows the OC CC difference.
I started diving over 25 years ago and nitrox was an unknown let alone
trimix , I didn't do crazy deep air but it was deep enough to know my
head was seriously fuzzy I can't think of the last time I dived air, it was
always nitrox or trimix OC and just trimix CC now.

You had a different background than me. My highest cert oc was adv. Nitrox with Bsac and i did airdives to 50m +
I am not advertising deep air but was never interested in doing OC Trimix, so that was what i got.
So i turned towards ccr to go deeper and longer. Did my mod 1 with air dil.
The most difficulty i had was boyancy. I struggled the first 100 hours, the first 50 hours it was not seldom to pop up to the surface when i was in the shallows.
I am talking about me so helium was a no go until i sorted out my boyancy.
Did not want to risk any faster off gassing and risking to get bent

 

[Elmi]

For me, even the topic Is drifting, the thread is educational.
Why we can not keep up without insulting each other?

 

[Capt Morgan]

Funny you should mention the U-861, I was on it a couple of weeks back
and was diving OC for the first time since getting my unit.
I was shi**ing myself as to how my head would be on the dive, the last
time I was at that depth on air was the time on CCR on my course.
As it happened I was fine so I guess it shows the OC CC difference.
I started diving over 25 years ago and nitrox was an unknown let alone
trimix , I didn't do crazy deep air but it was deep enough to know my
head was seriously fuzzy I can't think of the last time I dived air, it was
always nitrox or trimix OC and just trimix CC now.

You had a different background than me. My highest cert oc was adv. Nitrox with Bsac and i did airdives to 50m +
I am not advertising deep air but was never interested in doing OC Trimix, so that was what i got.
So i turned towards ccr to go deeper and longer. Did my mod 1 with air dil.
The most difficulty i had was boyancy. I struggled the first 100 hours, the first 50 hours it was not seldom to pop up to the surface when i was in the shallows.
I am talking about me so helium was a no go until i sorted out my boyancy.
Did not want to risk any faster off gassing and risking to get bent

My OC trimix was done with the BSAC also, it was a good well
taught course that I enjoyed and took full advantage of.
CCR was never a route I planned on taking.
I tried a couple of units in the pool and didn't like them,
though I guess they were badly fitted to me.
I seen a unit for sale at a price that I knew I could sell it
on if it was not for me, so I bought it.
Fell in love with it and still have it.
I guess I was quite lucky to get a unit I
enjoy and be able to dive trimix from my
first course, I don't think I'd still be diving it
if my diving had to take a big step back.
As it is it was just a few months and even that
Was long enough.
Air as a dil and I'd still be OC.

 

[Elmi]

As i mentioned before my buoyancy was crap ccr for a long time. I am still not there where i ended oc but it improved.
Just saying imho as long your buoyancy on ccr is not good and you can not keep stops you should not dive mix dil, what was my case.
@ Morgan what is your opinion about that?

 

[Capt Morgan]

As said before it's a hard call, for me buoyancy was not
a problem, getting narked on CC was so for me it worked
out fine.
The mod1 mix ticket is for a light trimix (30%) from memory
and an mod of 48m.
As I mentioned earlier if you can hold stops I don't see a problem.

 

[PeterN]

Please direct me to research on using Helium mixtures for less than 20mtrs... as far as I know most work focusses on using it deeper than 40?

It also artificially (possibly, IMVHO) messes up the output from off-the-shelf decompression computers, and the ultra thin gas at shallow depth increases risk of free flow and performance of ADV making maintaining the PPO2 harder.

IMO (not Humble this time ;-) lots of divers use helium all the time for bragging rights, "yeah just another mix dive" knocking it off casually like they've been to the Brittanic when in fact they've been watching pretty fishies at no more than 25mtrs.

Divers in general should MTFU and use the right gas for the dive, Trimix for 10mtr training dives is plain stupid, there is nothing uncool about Air Dil.

The right dil for my diving is mostly 10/50.

I do this for several reasons, none of which involve any bragging. I like the consistent results I get when I poke my adv for a ppo2 adjustment. My rig has an easy to use shut off on the dil and I usually have it closed. In the shallows I run my rig as an O2 rig, always. The only thing I change is my BO.

I don't need to change my habits or set up other than suit bottle and BO between dives. There is no significant cost. A bottle of dil lasts many dives. My He bill pales in comparison to my beer bill.

If was planning a shallow dive, I would go OC. However it does happen of course. Then I get to practice my shallow water buoyancy skills and running my ppo2 manually. All good things to do.

Problems with computer modling on shallow dives? Really! Talk sense. Most likely on those dives there will be little or no deco. This speaks to your OP about folks over complicating things. Learn to adjust your regs.

As to the OP, what I see is newer Tec divers tieing themselves into knots over deep stops before they can even mange crisp stops. I see them pontificating on the benefits of various deco stratagies, before doing more than a trivial amount of deco. Then they do back to back 200 foot dives with little thought as to what amount of work loading that entailed. Also they are often quite unfit. To me the basics seem often overlooked.

Peter

 

[rjack]

Please direct me to research on using Helium mixtures for less than 20mtrs... as far as I know most work focusses on using it deeper than 40?

It also artificially (possibly, IMVHO) messes up the output from off-the-shelf decompression computers, and the ultra thin gas at shallow depth increases risk of free flow and performance of ADV making maintaining the PPO2 harder.

IMO (not Humble this time ;-) lots of divers use helium all the time for bragging rights, "yeah just another mix dive" knocking it off casually like they've been to the Brittanic when in fact they've been watching pretty fishies at no more than 25mtrs.

Divers in general should MTFU and use the right gas for the dive, Trimix for 10mtr training dives is plain stupid, there is nothing uncool about Air Dil.

Well I have a couple sets of CCR tanks and some are filled with 16/50 and the rest are filled with 18/25. The 16/50 is actually a huge wad of leftover OC gas from various twinsets that I put into a storage bottle, that's what it came out at. The 18/25 is just the 16/50 roughly cut in half with air. I use the 18/25 down to a planned depth of about 35m with air BO. Gives me some versatility if I need to dip a little deeper. I have not done any >60m CCR dives at this point. If I did I would probably bring a slightly leaner dil O2-wise. I have done some 20m dives on leftover 16/50 and it behaved just like I expected it to.

I have not had a problem with the ADV dribbling. Like Peter, I use a shutoff. Other than testing the ADV, I run the unit on O2 only shallow (<~5m). I don't understand the maintain ppO2 problem you cite; I have an eCCR though. Can you explain that issue?

I'm not sure what research your looking for? Or why my shearwater is more or less happy with air vs these trimixes? It doesn't really care what depth I'm at.

 

[Randy Thornton]

Problems with computer modling on shallow dives? Really! Talk sense. Most likely on those dives there will be little or no deco. This speaks to your OP about folks over complicating things. Learn to adjust your regs.

As to the OP, what I see is newer Tec divers tieing themselves into knots over deep stops before they can even mange crisp stops. I see them pontificating on the benefits of various deco stratagies, before doing more than a trivial amount of deco. Then they do back to back 200 foot dives with little thought as to what amount of work loading that entailed. Also they are often quite unfit. To me the basics seem often overlooked.

Peter

Couldn't agree more with this part of your post!

 

[rossh]

Quantify "Massive" for us please? Its not an SI unit to my knowledge.

In this case is Massive- Alot, More than usual, More than could reasonably be expected or Surprisingly more than thought possible?


Perhaps the gas expanded as the victim ascended creating a Massive amount from a Usual one?

Hi Ben,

The "massive" VGE is Simon's description, and its the only technical description offered so far. Quantified - it would need to be extreme, as this man died very quickly. He boarded the boat, clutched his chest, collapsed and died shortly after.

So my question is to get more explanation on this and the process needed to create a cardiopulmonary DCS as applied to the victims situation.

Your suggestion sounds OK, but it leaves a hole for what happened during the 30 mins of normal deco he did - one would expect normal off gas had occurred, leaving no extra gas in the veins to generate the suggested massive VGE surge as he exited the water. Plus we don't normally have a lot of VGE in the dive, so to make the massive VGE in the first minute or two of surfacing from a normal deco, does not seem likely.

So maybe we should be looking at the other end of this - what went wrong with the lung, to not work properly under normal conditions? Or perhaps the cause was not VGE, but some other problem in his chest?

 

[Randy Thornton]

Ross, seriously, do you have the necessary medical training to second guess multiple medical doctor's opinions on the cause of this man's death? I don't understand why it seems so implausible to you that different people's bodies' physiology respond differently to nearly identical stimulus. Regardless of what your "math" says, everyone's bodies are different, and it doesn't necessarily mean that someone's circulatory system is defective simply because they got bent.

I have been on multiple dives where I have seen one member of the dive team exhibit symptoms of decompression sickness while following the same exact profiles as the rest of the team, for no obvious reason. It just happens!

 

[X181]

Ross, seriously, do you have the necessary medical training to second guess multiple medical doctor's opinions on the cause of this man's death? I don't understand why it seems so implausible to you that different people's bodies' physiology respond differently to nearly identical stimulus. Regardless of what your "math" says, everyone's bodies are different, and it doesn't necessarily mean that someone's circulatory system is defective simply because they got bent.

I have been on multiple dives where I have seen one member of the dive team exhibit symptoms of decompression sickness while following the same exact profiles as the rest of the team, for no obvious reason. It just happens!

Why it is so implausible is that if it is that rare, we have only one public case over all the years of diving, so how many cases may those experts have seen? None? One? So basically they may be experts but not for cardiopulmonary DCS.

 

[Randy Thornton]

Why it is so implausible is that if it is that rare, we have only one public case over all the years of diving, so how many cases may those experts have seen? None? One? So basically they may be experts but not for cardiopulmonary DCS.

Are you somehow privy to this statistic that you are quoting or did you just create that out of thin air?

 

[X181]

By the way to experts and courts and how wrong they maybe. There was a scandal in sweden, still is. Google for "Sture Bergwall" and see how wrong things can go over years with judges and many experts involved....