Should TDI Helitrox replace AN+DP?

[CAPTAIN SINBAD]

Tanzania could become top helium producer - African Business Magazine

By 2021 they say.

 

[ChuckP]

To him, making conservative rules that would apply to a vast population was often a substitute for more in depth knowledge. He wanted all his students to understand various components that factor into narcosis and none of those would be necessary if the technical diving population was being trained to switch to Helium at the lowest common denominator. He was of the opinion that WOB (Work of breathing) has a lot to do with how Narced you would be and managing WOB was one of the fundamental aspects of Narcosis management in his view. So there was a skill or technique to diving deep while maintaining brain function and it was not repeated and constant exposure.

He was coming from the background of commercial diving and commercial divers often dive solo. Knowing ones own limits and how one would respond to Narcosis on an individual level was of greater importance than throwing away that knowledge to become part of a "team." He mentions that he is comfortable diving to 200' on air as long as the dive permits him control of all factors that effect narcosis. He says that he has used Helium shallower than 200' when dive was complex or factors effecting narcosis were outside his control etc but there was no "one size fits all dives" approach in his mindset. Instead a fundamental part of the training of a technical diver in his view was to understand what would work, where.

This right here is the way I was taught - it goes absolutely against GUE standards - it's the open ears, eyes and mind style of learning. It's the diving is different all over the world type of learning. The dive style, the effort, the environment the so many factors related to any given dive - dealing with issues - learning some standardized system designed for the weakest link teaches you none of that and until you've spent weeks on a boat with someone of that mindset learning with an open mind, you'll never get it - which is ok if that's what makes you feel warm and fuzzy.

All due respect to John, I think he's dead wrong. There's nothing precluding me from understanding the concepts behind gas selection and narcosis management. If you come out of a T1 course and all you know is that GUE says 18/45 between 150-200 and that's just the way it is, your instructor needs to find another job. I can fully understand the factors that contribute to narcosis and how modifying my gas properties will affect that and still choose to dive standard gasses for other, very valid reasons. The education argument holds zero water for me.

I love the idea that he'll dive air to 200 if he can control everything, as if that's even possible. John comes from the New England wreck diving school. They accepted helium use about as grudgingly as possible. Dress it up however he wants, he's advocating for a narrower safety margin for no real benefit.

You couldn't be more wrong here period. He advocates for a more educated diver - that educated diver makes his or her own decisions based on many factors. Hearsay from what you read on the internet or what buddies have said is BS - talk to him with an open mind, take a class he offers - most of all, listen - then decide for yourself. He is an absolute nut on knowledge, thinking that he shoots from the hip is far from reality.

Deep air is dangerous, as is teaching deep air. More correctly, discussing deep air while teaching trimix or some form of it is the appropriate answer. In my opinion, an instructor taking a student on a deep air dive is asking to eventually have a bad day.

It's obvious you've got your opinion set in your mind, and that's fine. Just realize that it's an antiquated view and helium is becoming the norm for most agenies at depth. You're welcome to dive how you want to dive as long as you're not hurting anyone or getting a dive site closed. If we were on a boat doing a 150 ft dive and you showed up with air, I'd sure as hell stay way far away from you.

Define deep? 150'? Where at? The cold Atlantic or 80 degrees here in Cozumel? Working in the current or drifting with it? Some cave that you penetrate 2000' or some 150' open water dive where your surface GF never gets much over 100??? Do you dive to 110 foot five days a week or once a month??

You see, there's way too many factors involved to wrap yourself in that blanket. Some folks point is that by wrapping yourself in that blanket, you will be incapable of dealing with an absurd crisis if it were to ever happen - you are not being given all the tools to avoid the boogy man.

No disrespect intended, but that's some serious "both sides are the same" BS. One is dramatically and provably safer than the other. If it's too expensive, that's your choice. But pretending that those are even remotely comparable is a joke.

I could dive Helium every day of the week for the next 30 years but why? I choose where, when and what to dive - I'm not saying there's no need for Helium, not at all. In a cave, 110' deep, 1000 yards back - yea, I'm probably breathing helium; but drift diving at 150', nope.

This whole thread is about Helitrox replacing AN/DP. My opinion is absolutely not but any DP diver should in fact take Tri Mix one as it relates to open water diving - my opinion probably would differ if I dove caves. Helium has it's place, just not everywhere some agencies put it.

My personal experience: If I'm out of the water for two weeks then dive to 100', I feel it - three days back diving and it's a non issue. I live in Cozumel, mostly dive five days a week - these are for the most part lazy drift dives to 100' with gradually shallower profiles. I've also been CO2 narced bad at 80' on a ****** dive with a ****** diver - my training allowed me to recognize what was happening and thru that experience, how to deal with it.

I feel strongly that any diver should learn and look at all aspects in the conditions that they will put themselves in. CO2 hit at 80'? - go up, call the dive. The problem lies in Deco diving, you can't just always end the dive and go to the surface - you best have the mindset, skills and where with all to solve the problem underwater and that takes knowledge and experience. Experience doesn't come in a box, but some of it can be taught - the knowledge absolutely can be taught, you just have to listen.

Helium - it can provide a clearer mind, it does provide a lower WOB - but it don't solve all your problems, it is one tool is all.

 

[helodriver87]

You couldn't be more wrong here period. He advocates for a more educated diver - that educated diver makes his or her own decisions based on many factors. Hearsay from what you read on the internet or what buddies have said is BS - talk to him with an open mind, take a class he offers - most of all, listen - then decide for yourself. He is an absolute nut on knowledge, thinking that he shoots from the hip is far from reality.

The problem lies in Deco diving, you can't just always end the dive and go to the surface - you best have the mindset, skills and where with all to solve the problem underwater and that takes knowledge and experience. Experience doesn't come in a box, but some of it can be taught - the knowledge absolutely can be taught, you just have to listen.

Helium - it can provide a clearer mind, it does provide a lower WOB - but it don't solve all your problems, it is one tool is all.

I'm sure he teaches a great class. He has a ton of experience. But pushing narcosis limits just to see where you turn stupid so you can "make informed decisions" is needless risk. It provides no benefit other than giving people justification for not shelling out for a more expensive fill. I don't need to know what I feel like at 150-170 on air. Decades of experience tell us that most people are pretty impaired and it's better to just avoid that altogether. You don't need to push limits to understand and apply the concepts.

Your second quote pretty much makes my point for me. You have to solve the issue underwater, your skills and knowledge need to be on point. You know what immediately improves all of that, and at zero cost beyond the financial? An appropriate breathing mix. Nobody has ever come up from a dive saying "you know what, that was fun, but I wish I'd been a bit more narced". You're dressing it up in flowery arguments like "knowing your limits" and being more educated, but at the end of the day, the only real cost in question is financial. You aren't safer, you aren't more educated than someone who uses standard gasses, you're just choosing to spend less. Which is fine, just don't pretend it's anything else.

 

[ChuckP]

An appropriate breathing mix

for a particular dive - add those words and I agree with you. An open water, non working dive to 150' is not on my Helium must have list.........

But pushing narcosis limits just to see where you turn stupid so you can "make informed decisions" is needless risk

- I don't remember doing that in class, maybe i was narced the whole time.....

My point is simple - Helium has a place, has many places, just not on every dive below 100' or some arbitrary number.

 

[PfcAJ]

My personal experience: If I'm out of the water for two weeks then dive to 100', I feel it - three days back diving and it's a non issue.

Whether you "feel it" or not doesn't matter. Its there.

Plenty of drunk people think they're fine to drive, just ask them.

You're trying to self-assess of your level of impairment WHILE YOU'RE IMPAIRED. Think that through for a moment...

 

[helodriver87]

for a particular dive - add those words and I agree with you. An open water, non working dive to 150' is not on my Helium must have list.........

- I don't remember doing that in class, maybe i was narced the whole time.....

My point is simple - Helium has a place, has many places, just not on every dive below 100' or some arbitrary number.

You can't guarantee that a dive will remain non working. Just like you can't guarantee that your planned gas usage will be enough or that you'll only need your primary light, etc. That's why we have reserves and redundancy. Breathing gas is no different. Planning for the dive to go right is a bad place to start.

Recent research by Simon Mitchell suggests that an EADD of 102 ft is ideal with an EADD of 128 being the maximum permissible. This is based on CO2 retention as a function of WOB. The only way to modify those numbers is with helium. The research and evidence is not on your side here.

 

[cerich]

The only way to modify those numbers is with helium. The research and evidence is not on your side here.

equipment choice, not just helium

 

[rjack321]

Nobody has ever come up from a dive saying "you know what, that was fun, but I wish I'd been a bit more narced".

There was a diver here who enjoyed the narc for quite awhile. He only dove air, solo, and fairly deep, but not beyond ppO2 limits that I know of. As I recall he had trimix training, but avoided using it. He claimed to have found a "famous" anchor in 180-200ft (on air), and kept trying to re-find that on future dives... He was a super nice guy who just happened to enjoy his solo wanderings around the silt of Puget Sound at 180ish on air. If anyone could "adapt" to narcosis it would have had to have been him, he dove these depths regularly for a couple years and enjoyed them.

One day, hard to know what happened...
He passed out, at depth. I guess he didn't completely lose consciousness, but he was zoned out and functionally incapacitated. This was no deeper than his typical air 180ft-ish dive and he had at least a hundred dives like this. His reg stayed in his mouth by some miracle, but he breathed his tanks down and started floating up. This is actually what saved his life as he regained consciousness somewhere around 100ft supposedly. He tried to complete some of his deco, but was lighter than usual and continued to struggle. Hard to know how much deco he had or how much obligation he completed - I never saw his profile or computer. Eventually he surfaced and started waving for help. The passenger ferry saw him almost immediately. A mate jump in with a survival suit on, ditched his gear, and rescued him. He was in an ambulance within minutes and the chamber is less than 15mins from the dock. I don't remember how many HBO treatments he received, more than one for sure.

He lived
He lost his job as a firefighter
He's on disability
He's partially blind now
He has other nerve damage in his extremities
His bladder function is poor or non-existent
His name is Kirby

"Narcosis management" is a lie by divers who don't know science.

 

[helodriver87]

equipment choice, not just helium

What equipment reduces your gas density? Unless I'm way out of the loop, that's purely a function of depth and mixture.

 

[rjack321]

What equipment reduces your gas density? Unless I'm way out of the loop, that's purely a function of depth and mixture.

I suspect what @cerich was getting at is that net WOB is a function of equipment and gas density.

I don't know what equipment was used to derive the EADD of 102ft and max EADD of 128ft but a different regulator or CCR could alter the WOB and hence the recommended depths.