TDI Extended Range - last words of advice?

[Kern]

You would be be better served to read all the post in the thread. I don't know how to make my posts come out in crayon. Must be a system glitch.

As to the rubbish above, it's just like water off a ducks back.

Ahh, found it.

In the case of your comments about those criticizing deep air not having done it, you are incorrect in this case.

.

Wouldn't it have been just as easy to say, yes I have or I answered that in post XY.

 

[Tortuga68]

Does anyone else remember when this thread was about helpful advice for someone doing their TDI Extended Range course?

 

[Divin'Papaw]

Does anyone else remember when this thread was about helpful advice for someone doing their TDI Extended Range course?

.... about 55 posts back.

There are and always will be differences of opinion on this topic. Both sides aren't going to convince the other. If you think deep air is Satan's spawn then do your training with like-minded agencies such as GUE, UTD, NAUI Tech. If you feel it still has a place in certain situations and certain locals, then go with TDI or PADI DSAT. I'm not really sure what camp IANTD falls into any more. Maybe both.

Beating each other black and blue in these forums every time the topic comes up does not serve any useful purpose.

 

[DA Aquamaster]

Well...the thread is a bit instructive between the lines, but it is missing some historical context.

In the past, trimix (and even nitrox) was bad, and deep air was good - although despite popular myth claiming otherwise, divers did recognize the limitations it imposed. Now, deep air and in fact any END below 100' (or even 60' in the extreme cases) is considered "bad" and trimix is considered "good" by many divers and certain agencies, because.....well mostly just because someone said it was.

Somewhere in the middle the concept that deep air experience offerred a lot to the progression of a technical diver's training, ability and experience has gotten lost. In the 1990's you'd have been hard pressed to find an instructor who would teach you any form of techncial diving unless you have at least a hundred dives with at least 25 of them below 100'. In short, deep air exerience was a requirement for further technical training. It also seems to be ignored that a plain old advanced open water cert allows mere mortal AOW divers to dive to 130' on (oh the horror!) air.

Now, the END extremists will claim that is way too deep, especially for OW divers to dive on air - but that again ignores some of the basic facts such as OW and AOW divers used to do it all the time 20-30 years ago with acceptable safety, and it is not the safety of deep air that changed but rather some dumbing down of OW and AOW classes along with some inflation of the perceived (versus actual) risk of narcosis at what are still really mild depths. I honestly know divers that feel 100' is fine, but fear going to 110' feet in the same crystal clear tropical water as it violates the 100' END.

Maybe more significantly, NACD and NSS-CDS certify their full cave divers to dive to a maximum of 130' - giving creedence to the idea that an END of 130' is ok even in a cave for a properly trained and experienced diver, and this is an opinion from agencies that are serious about safety and accident analysis.

Personally, I think if a diver looks at it objectively they will see some advantages to deep air. There are huge numbers of wrecks and reefs in the 100-150 ft range where no serious penetration will be done, where the viz is good and the current not overly strong. In those conditions a well trained, experienced and prudent diver with deep air training and experience who knows his or her limitationswill not encounter any issues they cannot resolve on air and trimix is basically END reduction over kill. That is of course, by definition, heresy to the END extremist and their training agencies.

Also look at it from a practical standpont - if you bring along a set of doubles with mix and the swells pick up and the boat ends up diving on an 80-100' wreck rather than on the 150-165' wreck you planned on, you either have additional sets of doubles on board (or at best in the truck if the destination is changed at the dock) with air or nitrox or you end up wasting a $100 plus dollar trimix fill on a shallow wreck.

Maybe more importanly, the cost of air and nitrox is cheap and diver using those cheaper gasses will be able to afford to dive a lot more at depths below 100 ft than a diver using mix religiously for all dives below 100'. Over time that creates an enormous discrepency in dive experience. So when you fast forward a few years, and are diving a deeper wreck like the St. Augustine on trimix, who do you want with you? A buddy with a few hunderd dives below 100' on air or nitrox on top of at trimix cert, or a diver with maybe 30-50 dives below 100' all on trimix? All other things being equal, I'll take the diver with more experience every time. Mix may improve cognitive functioning at depth, but it is not a short cut for real world experience.

There is also the training side of the equation. There was some fairly significant research done with test subject who had not been indoctrinated about narcosis effects one way or the other. During their dive training one group was told that narocisis effects were severe and occurred at even comparitively shallow depths, while the other group of divers were told narcosis effects were manageable even to fairly extreme deep air depths. In effect both groups were trained to have different expectations about their ability to deal with narcosis.

Post training, both groups were given mental and physcial tasks under water and the two groups displayed remarkably different abilties and times on the various tasks with the first group expereincing narcosis issues and even failing to complete tasks at very shallow depths, the second group on average did almost as well at deep air depths as they did at 60'. In short, there is a psychological factor involved where a diver who expects to get debilitated by narcosis will and where a diver who is trained that they can function effectively under the effects of narcosis will function effectively to much greater depths.

The results of that study are of course automatically discounted and discredited by the END extremists - though as a trained psychologist I can assure you the results are consistent with human behavior and psychologcial theory.

One value if a deep air course that many divers notice is that once they experience narcosis at deep air depths, they do a better job of recognizing it even at comparatively shallow depths. That experience consequently adds to the diver's safety even at an END in the 100' range and is a benefit later even on trimix dives where narcosis is reduced, but still present.

The other "training" issue is that trimix training is expensive - plan on $1500-$2000 for a class - and is consequently a great revenue source for shops and instructors. So like it or not, at least some trimix instructors have a vested interest in promoting trim mix over deep air in areas where the bulk of the diving could be done safely on air nitrox. You have to at least consider that you will encounter biased as opposed to totally objective opinions when seeking training and information about trimix verus deep air diving and those biases will occur due to both agency doctrine and cash flow needs.

The discussion has always been how deep is too deep on air and that is in the rela world a very individual decision based on the individual diver, his expereince and training and the environmental conditions. Where the issue has gotten so horribly polarized is in a few training agency doctrines that firmly and arbitrarily state that any END below 100' is bad for any dive and any diver at any time.

All of which goes back to my original post. There is a great deal of value in extended range, especially if you add the extra couple of mix dives needed to make it a basic trimix class as it will give you both deep air and trimix experience and leave you well prepared to make an intelligent decision about the gas you need on a given dive. A decision based on something other than agency dogma, or the (believe it or not) often less informed opinions of divers trained that any dive with an END below 100' is dangerous.

 

[battles2a5]

Great post, DA.

 

[Bismark]

Well...the thread is a bit instructive between the lines, but it is missing some historical context.

In the past, trimix (and even nitrox) was bad, and deep air was good - although despite popular myth claiming otherwise, divers did recognize the limitations it imposed. Now, deep air and in fact any END below 100' (or even 60' in the extreme cases) is considered "bad" and trimix is considered "good" by many divers and certain agencies, because.....well mostly just because someone said it was.

Somewhere in the middle the concept that deep air experience offerred a lot to the progression of a technical diver's training, ability and experience has gotten lost. In the 1990's you'd have been hard pressed to find an instructor who would teach you any form of techncial diving unless you have at least a hundred dives with at least 25 of them below 100'. In short, deep air exerience was a requirement for further technical training. It also seems to be ignored that a plain old advanced open water cert allows mere mortal AOW divers to dive to 130' on (oh the horror!) air.

Now, the END extremists will claim that is way too deep, especially for OW divers to dive on air - but that again ignores some of the basic facts such as OW and AOW divers used to do it all the time 20-30 years ago with acceptable safety, and it is not the safety of deep air that changed but rather some dumbing down of OW and AOW classes along with some inflation of the perceived (versus actual) risk of narcosis at what are still really mild depths. I honestly know divers that feel 100' is fine, but fear going to 110' feet in the same crystal clear tropical water as it violates the 100' END.


The discussion has always been how deep is too deep on air and that is in the rela world a very individual decision based on the individual diver, his expereince and training and the environmental conditions. Where the issue has gotten so horribly polarized is in a few training agency doctrines that firmly and arbitrarily state that any END below 100' is bad for any dive and any diver at any time.

quote]

DA, I was pretty much done in this thread, except that I see a little bit of light at the end of the tunnel here. I enjoy your well reasoned posts and though we may on occasion disagree with our opinions, I respect your opinions and particularly how well you present them.

You may find it surprising that I agree with many of your statements. You may also find it surprising to learn that contrary to the comments of some, I am a very pragmatic diver, and I would not consider myself doctrinaire. Like you, I have been diving for a long time and have watched the evolution of the sport as it has undergone several "phase changes". As my diving became more challenging, and I became older, my personal risk assessment changed and I realized that I was no longer bullet proof, or even invisible after all. I think my time in the miltary in a "risky" occupation also signigicantly contributed to this change. In any case, my views are constantly being reexamined in the light of new information. I do not take anything at face value unless it passes the "BS" test.

Okay, enough back ground information for now.

As you mentioned, in the past, trimix and nitrox were "bad" and deep air was "good". However, we have seen that as our understanding of using nitrox increased, this view has changed considerably. As I understand it, next to OW, the most popular diving "specialty" is now a nitrox certification. All this in only 15 years. In that same time, trimix use and training has become more and more widespread, and accounts for a consistently growing proportion of advanced dive training. Will this continue and follow the pattern of nitrox? I think so, but for various reasons it will not grow at the same rate. Cost and availability are two factors which will keep trimix training from moving ahead as fast as nitrox training did, but the graphs would have a similar shape I think.

I see a big problem in that as the diver education model has become more and more driven by market economics, what divers are learning about nitrox use and even trimix use is becoming more washed out every day. How many times have we seen on SB even, a complete lack of understanding about what the benefits of nitrox are, or what is actually happening in our bodies when we use EAN? This same thing is happening with HE use. Our society as a whole seems driven to look for the single "silver bullet" to solve all our problems, from weight loss to bottom time and decompression in diving. We have always had a way to lose weight; quit eating as much and exercise more. Yet we are still looking for the "one pill a day" to fix the problem. This is the same thing with nitrox and HE use; nitrox was touted as the solution to all our decompression problems, giving us more bottom time, less decompression stress....etc. Now HE is touted as the next great silver bullet and all you need to do to become a great diver is put HE in your tank. I can think of few things that scare me more than putting a high concentration of HE in the tank of a diver who does not have solid buoyancy control. And despite what many manufactuers would say, there is no shortcut to buoyancy control. There is equipment that will help, but the vast majority of this diving skill has to be learned, and practised, just as a practioner of any martial art must practise to become and maintain proficiency.

I also see some missunderstanding on the part of several posters about why some agencies may set an END of exactly 100'. I see this misunderstanding repeated time and time again with questions of equipment or diving practises. You can not successfully remove individual components from the "system" they were never intended to operate outside of. Unfortunately, even many of who you refer to as "end extremists" (pretty funny actually) do not understand this and get mired in arguing about one thing from a position of lack of knowledge. Then the whole argument starts to look pretty stupid and reverts to simple opinion based name calling. Simply, arguing for an END of 100' based soley on an arbitrary number does appear silly. Until you understand where this fits into the bigger picture in terms of standardized gases, set PP02's, decompression, etc. Granted you need to understand the system as a whole to see this, and that doesn't happen right out of the gates for anyone. It has taken me several years of pretty constant use and thinking to have things all kind of "fall in to place" for me, and I didn't just fall off the turnip wagon.

I think you really hit the nail on the head about the dumbing down of OW classes. Students no longer are given the opportunity to develop the critical skills necessary to being a safe and comfortable diver. Now give them the opportunity to put HE in their tanks and you have a recipe for disaster.

In all fairness, If I recall correctly, 130' was never chosen as the max depth for recreational diving based on END considerations so your point that if "130' was okay for rec training why all the fuss now?" doesn't work for me. I believe your argument would have more strength if 130' was the origional END and this was revised, but I don't recall that this was the case.

Ultimately, every diver will make their own risk assessment. I just wish that they are able to do so from a position of being informed, one way or another. My personal experiences with higher END's and my knowlege of the bigger picture of my diving practises have led me to make what I think are informed decisions for myself that fit within my risk tolerance. I don't suppose we will ever all agree on this topic, but I hope we could at least all start with the same baseline of knowledge thus making missunderstanding less likely.

Thanks again for your post.

I am off to hit the water....

 

[rjack321]

You obviously do not, although I still would like to hear about what experience you and Bismark have with deep air that have led you to form these beliefs. Preach all you want, but most people are still going to do it. And most people see absolutely nothing wrong with it.

I have enough none trimix "NDL" dives in the 100-130' range (80-100?) and I remember them marginally enough to know that adding on another couple ATAs because one of the dinosaur agencies thinks that 180ft on air is a good stepping stone is bogus. The air based 180ft course prepares the OP for what? By your own reasoning: Warm, relaxed, no current deep diving with moderate narcotic impairment. Pretty limited conditions and its damn easy to get outside them fast IMO.

The reality is that ALOT maybe even most diving is in current, with stress (yes self induced sometimes), and cold, often dark water. So really this "stepping stone" is no better (just on a different scale) than a put another dime in weekend OW course training someone to swim around in a bathtub under supervision.

Alot, maybe even the majority of instructors, would recommend what was proposed to the OP pages ago, make it a normoxic trimix course. Even you probably aren't using ENDs of 130ft+ on trimix dives, why is that hmmmm?

 

[HowardE]

Rhone Man...

Something VERY important that you'll need to bring with you to Samana.... PANTS. (long pants)

 

[battles2a5]

I have enough none trimix "NDL" dives in the 100-130' range (80-100?) and I remember them marginally enough to know that adding on another couple ATAs because one of the dinosaur agencies thinks that 180ft on air is a good stepping stone is bogus. The air based 180ft course prepares the OP for what? By your own reasoning: Warm, relaxed, no current deep diving with moderate narcotic impairment. Pretty limited conditions and its damn easy to get outside them fast IMO.

And if you read the thread you would see that the OP LIVES and DIVES in the BVIs. Warm, relaxed, no current (or drift) diving if there ever was any.

Alot, maybe even the majority of instructors, would recommend what was proposed to the OP pages ago, make it a normoxic trimix course. Even you probably aren't using ENDs of 130ft+ on trimix dives, why is that hmmmm?

If you read the thread you would also recall that my very first recommendation was to take a trimix course. Try reading the thread, hmmmm??

 

[Chatterton]

I must be suffering from narcosis, because I can't even figure out what you are saying, other than slamming (I assume)TDI? TDI is a modern, involved, and dedicated certification agency. They work hard, and while most of the dive industry suffered last year, they experienced growth?

Why are you slamming TDI? Are you a TDI instructor, with some sort of insider insight that you can share? Under how many different training agencies have you been certified as an instructor? For me, it's just NASDS, NAUI, IANTD, and TDI/SDI, and I like TDI?

It certainly seems, you have not done the training, and you have not done the dives, and now you are slamming my friends at TDI? Instead of listening, you are ranting something about some kind of Trimix experience in the recreational depths, which is kind of irrelevant?

Now for a little more science. CO2 is the thing that has the most immediate impact on the body's acid/base homeostasis (Ph). CO2 combines with the bodies water to form carbonic acid, and a free hydrogen ion. More CO2, the body becomes more acid. Less CO2, the body becomes more alkaline. The changes can occur in a matter of seconds, and can not only impact the organs through the blood, but also travels over to the cerebral spinal fluid very fast, almost immediately.

For the diver, a couple of posters have mentioned how high WOB does create more CO2, the body then becomes acidic, and some divers might experience narcosis, with the exact mechanism for how this happens still up for scientific debate.

What about the other way around? how about the diver who hyperventilates in shallow water, like the diver who is diving beyond their experience limitations and has some anxiety? Less CO2, creates an alkaline situation. Does this diver get narcosis from too little CO2? What happens when your grandma gets anxious, hyperventilates, and feels lightheaded at the hockey game? You make her breathe into a paper bag, and try to calm her down.

For those who experience "narcosis" in recreational depths, maybe it is a less narcosis and more something else?

However I can't over emphasize, Rhone Man must bring pants!! No armband necessary.

Cheers

JC

I have enough none trimix "NDL" dives in the 100-130' range (80-100?) and I remember them marginally enough to know that adding on another couple ATAs because one of the dinosaur agencies thinks that 180ft on air is a good stepping stone is bogus. The air based 180ft course prepares the OP for what? By your own reasoning: Warm, relaxed, no current deep diving with moderate narcotic impairment. Pretty limited conditions and its damn easy to get outside them fast IMO.

The reality is that ALOT maybe even most diving is in current, with stress (yes self induced sometimes), and cold, often dark water. So really this "stepping stone" is no better (just on a different scale) than a put another dime in weekend OW course training someone to swim around in a bathtub under supervision.

Alot, maybe even the majority of instructors, would recommend what was proposed to the OP pages ago, make it a normoxic trimix course. Even you probably aren't using ENDs of 130ft+ on trimix dives, why is that hmmmm?