TDI Deco Procedures.

[SailNaked]

hmmm to piss off the Scuba cops or not to piss off the scuba cops?

Let assume I am only going to 130ft, and I plan to stay for 30 min and at most I will carry 2 deco bottles and I have 28% in my double 80s (cause that is what i have).

No class and I have a 59 min dive. (unless I use 100% @ 20ft then it is 49min.)

with Adv Nitrox I can use 50% and 100% and have a 48 min dive.

If the course is not meant to be taught by itself why is it? seriously for 11 less minutes in the water enjoying the fish?

Not trying to wad all yalls panties, just asking if the Deco procedures class is stand alone or if it is really useless without the Adv Nitrox.

I hear yall about Trimix, later I will go down that path, for now, just looking to have a reasonable bottom time on two local wrecks that happen to be at 130 ft.

 

[wedivebc]

Deco'ing on 40% is nickel rocketing at it's finest. Are you really willing to more than double the amount of deco time you have to save a few bucks?

What deco algorithm is giving you those results?

 

[wedivebc]

Not trying to wad all yalls panties, just asking if the Deco procedures class is stand alone or if it is really useless without the Adv Nitrox.

Yes the deco proc is pretty much useless without adv nitrox.

As far as the helium question is concerned there are a number of folks on here who are overly sensitive to nitrogen narcosis and will have you on He for anything deeper than a snorkel dive but for myself 130ft dive using 30% nitrox and a 50% deco mix is a good days diving.

 

[ucfdiver]

What deco algorithm is giving you those results?

Assuming back gas for the dive and a roughly 2:1 o2 to back gas ratio. Obviously each mix will throw it off slightly, lean mix being over 2x, and a rich mix like 40% being way less. No deco algorithm was used, since I didn't know an exact plan...But I've read enough of your posts to know that you're well aware of that

If he's going down to 150, I can see some use for 40% as a deeper deco gas, although I don't see why you would exclude yourself the use of 100%/50% when the two classes are typically combined. Also limiting yourself to nitrogen/oxygen only mixes for 150ft dives seems odd to me, but there's already enough debate on this board about that.

 

[rjack321]

Yes the deco proc is pretty much useless without adv nitrox.

As far as the helium question is concerned there are a number of folks on here who are overly sensitive to nitrogen narcosis and will have you on He for anything deeper than a snorkel dive but for myself 130ft dive using 30% nitrox and a 50% deco mix is a good days diving.

Actually most of us just get out of the water cleaner on helium than on N2 for say a 35min dive at 120ft. I did a few barely deco dives on air/nitrox back in the day and you sure get out sleepy.

I would do a dive to those depths on 28% or soemthing like that if push really came to shove. But N2 has alot of less than desirable properties esp. once there's alot of slow tissue loading.

I'm only recommending a "more modern" intro deco course prgression because they are readily available now and the OP's 120-130ft goals will probably be 150-160ft within 6 months anyway. Why not get a complete set of tools to make informed choices vs. getting a limited cert which leaves him wondering about what he's missing in his gases and concepts?

 

[wedivebc]

I am not disagreeing with you. I just think helium should be used with caution and should be used when needed. I am not convinced it is needed in an entry level tech training program and I think it has been made pretty clear by Doppler and others that 150ft is a max limit for deco procedures not a goal. My personal choice is that I will dive past 100ft on air and under certain circumstances will venture to 150ft without the benefit of helium but when available will always opt for the better gas for the application.

Actually most of us just get out of the water cleaner on helium than on N2 for say a 35min dive at 120ft. I did a few barely deco dives on air/nitrox back in the day and you sure get out sleepy.

I would do a dive to those depths on 28% or soemthing like that if push really came to shove. But N2 has alot of less than desirable properties esp. once there's alot of slow tissue loading.

I'm only recommending a "more modern" intro deco course prgression because they are readily available now and the OP's 120-130ft goals will probably be 150-160ft within 6 months anyway. Why not get a complete set of tools to make informed choices vs. getting a limited cert which leaves him wondering about what he's missing in his gases and concepts?

 

[SailNaked]

Thanks all for taking the time to comment. I will probably just wait till I get the Time/money and enough points with my wife to do the whole course. I suppose I have enough to keep me busy for a few months, maybe I can take Chatterton's course next April.

 

[Blackwood]

I think it has been made pretty clear by Doppler and others that 150ft is a max limit for deco procedures not a goal.

slight hijack, but I find that absolutely ridiculous. If TDI doesn't feel that the class should be taught to the training limit for reasons of safety, they should lower the training limit.

 

[rjack321]

I am not disagreeing with you. I just think helium should be used with caution and should be used when needed. I am not convinced it is needed in an entry level tech training program and I think it has been made pretty clear by Doppler and others that 150ft is a max limit for deco procedures not a goal. My personal choice is that I will dive past 100ft on air and under certain circumstances will venture to 150ft without the benefit of helium but when available will always opt for the better gas for the application.

Helium is not the enemy, N2 is

(data)...support the rank order of increasing DCS risk (He less than N2 less than Ar)...

Rubicon Research Repository: Item 123456789/2613

 

[boulderjohn]

I am not sure why we are talking about helium here, since it is not a part of either the Advanced Nitrox or Deco Procedures course. (IMO, it should be, but it is not. TDI holds helium off until later certification levels.)

As for whether you should take one course or both, you really need to take both at the same time. The TDI final exam for Advanced Nitrox has questions that are in the Deco Procedures course, and the TDI final exam for Deco Procedures has questions that are in the Advanced Nitrox course.

If you take the Advanced Nitrox course by itself, it does you no good, since you get no benefit from it. What will you do with the ability to use richer mixes?

If you take the deco procedures course by itself, it will do you no good, since you can't use the rich mixes you need for your deco procedures without advanced nitrox certification.