TDI - Intro to Tech - Necessary?

[loosenit2]

I am following this thought, as I am interested in doing AN/DP; but not interested in diving doubles. I do dive with redundant air and I have no problem slinging a stage btl in addition to a pony.

i just looked at course standards for AN and DP and doubles are not required, just cylinders sufficient for the dives. With that said I have no idea how you would do AN/DP level dives without doubles. Even with an HP133 you have 133.5 cuft of gas. Using a common gas planning methodology and rule of thirds you plan to have 150% of the gas you need and then only use 2/3 of what you have (1/3 out, 1/3 back, 1/3 just in case). So the max gas you would plan on using is 133.5/1.5 = 89cu ft. Using rule of thirds you would only use 60 cuft of gas total to get to either surface or next available gas. Using an RMV of .75cuft/min you are only talking about 15 min or less at 140 ft; not at all practical.

 

[loosenit2]

There is, I believe, an extended range air, component to the TDI course stream.

ER comes after AN/DP. AN/DP qualifies you to 150 ft. ER qualifies you to 180 ft on air. ER is not the most common course, much more common to move to helitrox or trixmix after an/dp rather than ER.

 

[tbone1004]

will be echoing many of the points made on this thread, but wanted to come at it from the instructor side.

When you sign up for a course like AN/DP, our job is to teach you what is called out in the course material.
Advanced Nitrox is a theoretical course only and there are no actual dive skills to teach and all of the course material should have been covered in a proper Nitrox course. It usually isn't, but it's not a course that is really involved to teach from a skills perspective and even from a dive planning perspective, it basically teaches you how to not blow yourself up with high fO2's.
Deco Procedures is a proper course that involves a lot of academics involved in dive planning for staged decompression and the skills required to not only hold those stops but also to safely conduct the gas switch. What is not included in these courses is teaching you how to dive properly with regards to buoyancy, trim, propulsion, and use of whatever primary breathing apparatus you are using whether it be sidemount or doubles. I will not teach this class outside of a full technical configuration, granted I'm also not allowed to from my agency but I think TDI will allow it.
Either way, many students have started to use things like cavern/intro to cave and/or AN/DP to learn the skills that they should have had prior to coming into the course and that is not fair to both the instructors and the students. From our side, it means that we are having to take time to teach a class that we weren't anticipating teaching, often requires increasing the number of days to finish the class, and also a higher fail rate since students did not have adequate teaching time on the subject matter they were supposed to have.
You'll see GUE fundies recommended heavily on this forum and any instructor should accept that in lieu of an intro to tech certification, but in agencies outside of GUE/UTD/etc. you'll also see "or relevant experience" taken in lieu of that certification. If you are diving with good mentors and can demonstrate the skills prior to the class then an instructor may waive that certification *for example, I do not require my university students to take intro to tech because they learn all of those skills at the basic open water level and learn how to dive doubles in their advanced course*, but in any event you should never use basic technical courses as a way to teach you how to dive properly.

 

[Wibble]

I am following this thought, as I am interested in doing AN/DP; but not interested in diving doubles. I do dive with redundant air and I have no problem slinging a stage btl in addition to a pony.

Then it's diving sidemount. Lovely config, a bit more fiddly to configure and don/doff kit, but my goodness it is good in the water.

Plenty of redundancy, plenty of options. Easier to carry around (single tins). Easy enough to use a decompression bottle.

ER comes after AN/DP. AN/DP qualifies you to 150 ft. ER qualifies you to 180 ft on air. ER is not the most common course, must more common to move to helitrox or trixmix after an/dp rather than ER.

Hope you're not thinking singles? If so, where do you keep your redundant gas supply? It's a damn long way to the first gas switch from 55m/180ft.

Diving a single with PONY and deco stage seems just silly. Twinset/doubles or sidemount.

 

[rjack321]

If it would make you more comfortable, I could mount my 30cu pony to my main and only sling 1 bottle.
One does not have to go to 150' to apply the knowledge from an AN/DP course. I am more interested in it, to give me the ability if I chose, to exceed my NDL. Of course proper prep and planning would ne required. To give me more time at say, the glass cloud sponge fields at a local dive site. My interest lies in future wreck, then a wreck penetration cert.
As far as Helium is concerned, I have not been past 126', where I was OK, not narc'd. There is, I believe, an extended range air, component to the TDI course stream. Eliminating Helium and the need for suit gas, which is actually quite minimal. I use my inflator to fight squeeze, primarily. BCD, primarily for buoyancy. Some I know, use the suit more for buoyancy. I did my OW, in a drysuit and have never dove in warm water.
A deco gas in a 40cu stage btl is easy peasy to sling. Pretty much all my diving, has been with a slung pony. I am very used to carrying one.

Shrugs sounds like you got it all worked out. I can say with a high degree of confidence you would struggle to find a buddy in my area showing up like this.

@girlwithbigtanks teaches AN/DP in Vancouver, maybe talk to her.

 

[Jim Lapenta]

While TDI allows a single cylinder for AN/DP, I don't. Doubles or sidemount. No discussion on this point. It becomes clear why when you start doing the math.
And like coming into a course without the skills you need, it's not fair to the other students and myself who are carrying the necessary amount of gas for the dives we do in the course.
Wreck penetration in a single tank? Sounds like suicide to me. Are there people that do it? Sure, there are also people who drive drunk and get away with it. Until they don't.
Running out of gas in wreck because someone used a single tank is selfish and puts the people who have to drag the corpse out at risk.
I do love those who say they were not narced at depth. I've had a couple of those who said that. When questioned about certain details however, they get the blank stare and act like you're lying about what was there. Or when you hit them with multiple failures in quick succession and they pretty much go into full mental shutdown or the eyes get wide like saucers and you have to grab them to keep em from bolting.
Too many people have "never been narced" until they are and someone gets hurt, goes missing for a while, or worse.
Everyone gets narced. Period. The degree of narcosis and the self-awareness of it is the difference.

 

[Wibble]

While TDI allows a single cylinder for AN/DP, I don't. Doubles or sidemount. No discussion on this point. It becomes clear why when you start doing the math.
And like coming into a course without the skills you need, it's not fair to the other students and myself who are carrying the necessary amount of gas for the dives we do in the course.
Wreck penetration in a single tank? Sounds like suicide to me. Are there people that do it? Sure, there are also people who drive drunk and get away with it. Until they don't.
Running out of gas in wreck because someone used a single tank is selfish and puts the people who have to drag the corpse out at risk.
I do love those who say they were not narced at depth. I've had a couple of those who said that. When questioned about certain details however, they get the blank stare and act like you're lying about what was there. Or when you hit them with multiple failures in quick succession and they pretty much go into full mental shutdown or the eyes get wide like saucers and you have to grab them to keep em from bolting.
Too many people have "never been narced" until they are and someone gets hurt, goes missing for a while, or worse.
Everyone gets narced. Period. The degree of narcosis and the self-awareness of it is the difference.

Oooh, you're describing the reason we dive on rebreathers

I remember doing a compression chamber dive with a bunch of other people. Bloody amazing thing to do!

We only dropped down to 40m/130ft and we were off our tits! Everyone was giggling like a load of schoolgirls. The tests they gave us -- simple arithmetic and mild problem solving -- was nigh-on impossible. Couldn't read my writing after either.

I dive with some helium in my mix. When I was on open circuit it was very expensive to do a simple normoxic dive. Used to cheat a bit, so 45m/150ft would have 20% helium just to get some of the nark off.

Then rebreathers... oh the joy of diving with helium on any dive greater than 25m/80ft. For deeper dives I'll mix in a lot of helium, shallower less. But due to the small amounts used it's $20/dive or thereabouts. Hate wasting it on the wing! Sure, add in $20k of rebreather, tech kit and training... ooh, a bargain!


Not intending to go off track, trying to illustrate how a little "ooh, let me do Intro to Tech" ends up with a serious investment. It doesn't have to, but you've no idea where you'll end up. Take every course seriously as you will rely on things you've learned in the early classes even on advanced deep diving.

Most of my diving's on the 35m/120ft through 50m/165ft range on wrecks. Lots of deco so I can enjoy my time on the bottom and my time at deco getting away from the world in my land of zen.

 

[rddvet]

As far as Helium is concerned, I have not been past 126', where I was OK, not narc'd. There is, I believe, an extended range air, component to the TDI course stream.

You don't think you were narc'd. As someone who didn't think he was narc'd for many years, you were absolutely narc'd. You just weren't aware of it. Put a little helium in your mix and do the same dive and you're response will be "wtf was I doing all this time."
Extended range air is stupid and dangerous. There's another thread about it right now. It's not only dangerous for the students, but it's dangerous for the instructor. Any GOOD tech instructor will talk you out of deep air imo. If an instructor is a big proponent of deep air I wouldn't use them.
You can do AN/DP in a single tank and be fine, but the point of this thread was to get advice on the best way to move to tech diving. The best way to do that is to dive doubles, learn them, get basic skills down, then start down the tech path. It will only benefit you in the long run. If you take an/dp in a single tank and a slung safety bottle and deco bottle, 5 years from now you'll realize how stupid of a choice it was.
Personally if you're planning to do an/dp and maybe add extended air, your money would be better spent on adding something like helitrox or recreational trimix (whatever tdi calls it).

 

[Efka76]

If you are really good with backmount doubles or sidemount diving then TDI Intro to tech is not required, however, if you you are coming from recreational diving and never dived in below mentioned configurations, its a must. Do not rush to get through AN/DP, these are pretty serious courses.

When I engaged into TDI AN/DP I was told that I am paying for training only, certifications need to be earned. This training was really had as instructor was really tough on me and my buddy. I passed it but I know people who were quire reasonable divers and they did not pass AN/DP.

 

[Tracy]

If it would make you more comfortable, I could mount my 30cu pony to my main and only sling 1 bottle.
One does not have to go to 150' to apply the knowledge from an AN/DP course. I am more interested in it, to give me the ability if I chose, to exceed my NDL. Of course proper prep and planning would ne required. To give me more time at say, the glass cloud sponge fields at a local dive site. My interest lies in future wreck, then a wreck penetration cert.
As far as Helium is concerned, I have not been past 126', where I was OK, not narc'd. There is, I believe, an extended range air, component to the TDI course stream. Eliminating Helium and the need for suit gas, which is actually quite minimal. I use my inflator to fight squeeze, primarily. BCD, primarily for buoyancy. Some I know, use the suit more for buoyancy. I did my OW, in a drysuit and have never dove in warm water.
A deco gas in a 40cu stage btl is easy peasy to sling. Pretty much all my diving, has been with a slung pony. I am very used to carrying one.

If you want to learn some light deco with a single tank, tec 40 is right up your ally. If you want to get into technical diving, a single tank doesn't make sense.
It depends on your end goals. Extend your recreational diving, or starting down the technical road.
"Begin with the end in mind."
I have heard that somewhere before.