Diving air to 60m

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Frankly the same happens on tree forums..... With the same result...... K
 
@mac64 I know a CMAS instructor who made a change and took a trimix course at 70.. (yes the guy with the big hit after a hypercapnia incident, spending time in the decompression chamber in Toulon).

I absolutely have no beef with your way of diving, or what you do... your life, your rules. But I find it very strange that you can profess stuff as being the absolute truth, like the advantages of trimix being a myth, WOB or hypercapnia being a non issue, when frankly you have no experience with any of this stuff. You have never done long deco dives, for crying out loud you do deco on backgas... you never have dived trimix... you have never suffered a CO² incident... so how can you be so sure of yourself. I'm know it's futile to try to change someone on a internet forum, but I don't get why you are not thinking in the back of your mind... "hey, there seem to be a lot of these internet warriors saying the same stupid stuff, let's see if I can start reading up on this, ask questions to some local tech instructors"... even if it's just to learn something and be aware.

Not you ... Trimix is a myth, and people having a hypercapnia incident need to see a doctor, they are not normal.

Most of the time I see people so sure of themselves they are teenagers not 65 year old guys.
What you like to do is pick out bits of my posts and either totally misquote them or quote them out of context, will you tell me where I said trimix is a myth? What I said is the notion that your safer on trimix is a myth. Personal safety is about personal awareness and knowing what your limitations are. Diving air can kill you. Diving trimix can kill you and diving a rebreather can kill. It all comes down to the person using them.
 
No, the problem is that YOU said it's not an issue for anyone because it's not an issue for YOU in your experience. you discard the science proving it is an issue and that helium IS safer because YOU haven't had a problem yet.

That "some" people might not have a problem isn't the point. The point is that the data, and science, and every other factual piece of material says that while some people "may" be okay on air, divers in general WILL be safer on trimix.

What works for you may continue to work for you forever, to say that science is a "myth" because it you feel fine diving air is just patently absurd however. That's why you can't provide one piece of scientific, objective evidence to support your statement.

Dive how you want to dive, but please don't come to the internet and try to convince people who may not know better that all the scientific evidence is wrong and they should risk their lives based on how your experience has been and contrary to the objective evidence about how to do things safely.
I’m the one that’s not telling people what’s best for them, the last thing I would do is tell someone what to do or how to do it. Adults get to make their own decisions. P.s will you tell me where I said science is a myth?
 
To all people who do not want to read through the whole thread. Most of the guys attacking @mac64 respect his decision on his diving practices, but his generalizing statements based on subjective feelings lack any trimix experience and ignore scientific facts from reputable sources and industry-wide safety practices, as seen below:


Considering this is a deco dive, the lack of safety reserve and many other aspects is alarming. Have you ever heard of lost gas / +5min / +5m planning and procedures? Are you even certified below 40m or is it just another piece of paper you do not need?


Congratulations, keep trying. With your attitude, you will get there.



So hard working/overexertion is always preventable? Congratulations, you are probably the only diver in the world who can be sure about that.


So aside from hyperbaric physiologist, you are also a material engineer? I hope that you do not fill untested tanks. But honestly/sadly, it would not surprise me.

I am not saying you cannot dive to 60m on air. I am telling you that if you think its safer than on Tx, you are seriously mistaken.



Air at 60m is about 8.5g/l. You might not notice it as the change is gradual and you are significantly narced in the end, but the gas density is in dangerous levels. But unless you try to switch to trimix at that depth to see the difference, there is no point discussing this with you are you have absolutely no clue what you are talking about.

You can discuss subjectivity of nitrogen narcosis and effects of WOB at 40m (bordeline). Not in 60m. Again, you just do not know how much you do not know / how narced in fact you are.


Again, Air at 60 is about 8.5g/l. Please see the table below to see how even 6-7g/l is dangerous.


Maybe with nitrogen. If you get CO2 hit from hard work at 60m, you are pretty much ******.

For more info on gas density, CO2 retention, WOB and narcosis (things @mac64 is subjectively immune to) please refer here: Alert Diver | Performance Under Pressure

Some important excerpts:
View attachment 532169
Figure 1 shows the proportion of rebreather test dives ending in failure due to an end-tidal CO2 > 8.5 kPa (top section of bars) and other causes of failure (middle section of bars) stratified by respired gas density. The numbers in the bars refer to the number of dives. At respired gas densities >6 g/L–1, there is a sharp increase in the risk of dive failure, with most failures being caused by dangerous levels of CO2 retention.

Helium appears to be the immediate solution for divers who are concerned about WOB and correlated medical issues (immersion pulmonary edema, CO2 retention, etc.) and for technical divers who are doing even normal dives to moderate depths. Seven times less dense than nitrogen, helium also ameliorates the severity of narcosis but brings with it a host of new obstacles, including extended decompression, cost and high-pressure neurological syndrome (HPNS) concerns.

If you want to know more about why even on OC the gas density is an issue, take a look at this video:


The gas density is WOB and CO2 retention issue not because of the limits of OC/CCR, but due to the way, your lungs are built.


Be smart and keep an open mind to learning new things from reputable sources.
Sorry but that post is to long. I’m just back from a brilliant dive (solo) on the S.S.Bandon and I’m feeling lethargic from all the nitrogen.
 
I’m feeling lethargic from all the nitrogen
Ever considered another gas than air? No? I thought so. Try it, it might broaden your experience base.
 
[...]

Air at 60m is about 8.5g/l. You might not notice it as the change is gradual and you are significantly narced in the end, but the gas density is in dangerous levels. But unless you try to switch to trimix at that depth to see the difference, there is no point discussing this with you are you have absolutely no clue what you are talking about.
[...]
I have been certified for OC trimix for quite a while (hipoxic) but then when the cost of filling started adding up a friend convinced me to move to CCR.
Now the nice thing about CCR is you can bring down multiple gas and you can plug them into the loop and make many gas switches.

I did a little experiment. I had as onboard dil AIR and I went for a deep lake dive. My bailout bottle was 18/45. I went down to 45 meters on air, plugged in the off board diluent, did a loop flush and TADHAAA! Lights on, the curtain went up and breathig become a breeze.

Just saying .... if you did not try, give it a go. I did not try the opposite though (IBCD risk there) and kind of risky for the speed of the onset of narcosis ... never attempted in OC since you do not bring breathable air during a TMX dive but it is not an issue with CCR ...

Cheers

Fabio
 
The first time I breathed trimix was at 45 meters in a canyon. I was diving BM tanks with air when my buddy, who had doubles with trimix handed me his long hose. For the next ten minutes, we swam around, finding nothing interesting to look at. I didn't notice any difference. The next trimix dive in 2002 I made was a little deeper. The lack of narcosis was noticeable as we were diving a site we had done on air many times before. I didn't notice any difference in breathing, nor have I noticed any difference during any dives since then. The only real difference I've found has been a reduction of narcosis with trimix.
 
The first time I breathed trimix was at 45 meters in a canyon. I was diving BM tanks with air when my buddy, who had doubles with trimix handed me his long hose. For the next ten minutes, we swam around, finding nothing interesting to look at. I didn't notice any difference. The next trimix dive in 2002 I made was a little deeper. The lack of narcosis was noticeable as we were diving a site we had done on air many times before. I didn't notice any difference in breathing, nor have I noticed any difference during any dives since then. The only real difference I've found has been a reduction of narcosis with trimix.

From what I understand, the WOB reduction is more noticeable on a breather. I notice it on OC, but it's apparently a night and day thing on CCR.
 
Sorry but that post is to long. I’m just back from a brilliant dive (solo) on the S.S.Bandon and I’m feeling lethargic from all the nitrogen.
How was the dive?
I dive deep air routinely rec/tec. I would put some helium into the mix if I am doing penetration in a wreck but rarely in open water.
 
How was the dive?
I dive deep air routinely rec/tec. I would put some helium into the mix if I am doing penetration in a wreck but rarely in open water.

Probably fine, considering it's at 110 fsw or so. Not ideal air territory, but then again, what is.
 
https://www.shearwater.com/products/perdix-ai/

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