Equipment for Adv Nitrox and Deco Proc

[Rick Inman]

I'm interested in Adv nitrox and Deco for the experience and understanding of how the gasses affect human physiology.

I think you may be disappointed in your class, if you are looking for a great deal of information on the physiology of gas transport. I believe most advanced classes of this kind are mostly focused on the practical aspects of how to calculate decompression, and the physiology is pretty much limited to describing O2 toxicity and how to figure OTUs.

Depends on the instructor. I got way more discussion on this than was required, than I wanted, and that I was able to retain. However, in general I agree. You can probably get more gas physiology and theory by doing some searches right here on ScubaBoard.

As to the doubles, you could see my heal marks all the way to making that transition. But once I got into the deco aspect of diving, moving into doubles is like falling off a log. And now I have 2 sets and dive them (almost) exclusively.

It would kill me to spend more than half the cost of a set of doubles on rental fees.

 

[HowardE]

For my upcoming course...

I'm taking it in the Dominican Republic (where my instructor is) so I won't be bringing my own tanks. I am bringing my regs, bp/w, bags, reel, etc.

If I was going to continue diving doubles... I do have several tanks at home that could be doubled up... Like the OP - I don't plan on doing deco dives all the time, or diving doubles all the time... But I'm taking this course to expand my knowledge of diving and to hopefully challenge myself a little bit. I KNOW my instructor is a knowledgeable guy, and will hopefully make this course a valuable one.

I also am doing the course to expand my knowledge of diving. However, I must say that after reading the book (student manual) from TDI for Decompression Procedures - I will say (honestly) that there's not much NEW info to me, after reading so many discussions here on ScubaBoard. To be clear... Am I saying that SB is a substitute for a class? Definitely not... But I am saying that this isn't earth shattering new info thanks to some of the great postings here on the board.

I have only done a few dives in doubles. Actually - I did dive #3 and 4 with Rick Inman (thanks for the avatar pic ). My 3rd dive in the doubles was on the Spiegel grove. Personally - I didn't have any problems adjusting to the doubles at all. However - I did have more than 500 dives before I ever tried doubles. So for me... The transition was no problem whatsoever. For me - I didn't have any issues with buoyancy, or trim.

Also - as DA Aquamaster explained, and as the course manual states... A Single cylinder with an H valve is acceptable, and for someone like me; a single 130 is plenty of gas (without catastrophic failure) to complete a moderate length decompression dive. Although - I wouldn't recommend this to newer divers with higher SAC rates.

Getting back to the OP's original question and subsequent response... I think you're on the right track, and I hope the course gives you what you're looking to get out of it.

I've said before... Any class can be either a nothing gained experience if you don't want to take anything from it.
Any class can also be valuable - IF your goal is to take something from it, and go in with a positive attitude and try to learn. Hopefully if you're not learning enough, or not being personally "challenged" then you should press your instructor to take it up a notch. You are ultimately the factor that influences how much you walk away from any course with.

 

[Flightlead]

I have a Sausage... would I need an additional one or a bag for the Deco tank?.. or are you referring to the fact that the Sausage or Bag can be used to create positive buoyancy if my BC fails?

I recommend a 100lb lift bag, not a 50lb

 

[rongoodman]

I wasn't impressed with the TDI Deco Procedures text either, compared with the information available here and over on The Deco Stop, along with the GUE materials. It was written in 2000. Even the Extended Range/Trimix text has no mention of Rock Bottom/Minimum gas in the dive planning section and says that deciding if you have enough gas to rescue a buddy who is out of gas is "one HARD question to answer"(p. 38). (I didn't see any mention of reserve gas planning beyond 'thirds' in the DSAT book either.) I have been seeing rumors that the TDI texts are being upgraded, with the new Advanced Trimix being very good.

 

[Divin'Papaw]

The TDI manuals (Adv. Nitrox and Deco. Procedures) are sorely in need of revision. According to my instructor those revisions are underway and the new manuals will hopefully be out later in the year.

 

[Divin'Papaw]

I recommend a 100lb lift bag, not a 50lb

Really? That seems like overkill for drifting deco. TDI standards require only >=25 lbs. I've been more than happy with a 50 lb bag.

 

[Meng_Tze]

..... Even the Extended Range/Trimix text has no mention of Rock Bottom/Minimum gas in the dive planning section and says that deciding if you have enough gas to rescue a buddy who is out of gas is "one HARD question to answer"(p. 38).....

And yet it is not that crazy if you think about it. Mind you I am not saying I fully subscribe to it, but I can see where they come from and why it is written.

When you get into serious tech diving you are increasing risks dramatically. Usually you have a ceiling (either physical and/or virtual), are at greater depth and work with more and more exotic gases and all that comes with it (hyp(er)oxia, MOD's, PPO2's, CO2, IBCD, PPN2 etc). There could be instances where even though you did plan for gas losses, you need to assess if giving your buddy gas is going to put yourself in a situation that will become irrecoverable. This is a decision all divers need to make, but it is more at the forefront with tech diving.

Look at an example with Don Shirley and David Shaw. Don went after David to try to rescue him, but after he started to have issues himself, he had to cut that decent off and take care of himself. While he did not per se have a gas volume issue, it does illustrate the mindset.

On paper we all can plan things, in reality at that crucial moment when it can quickly become a matter of living or suffering severe results, you decide and move on with your decision.

 

[ucfdiver]

And yet it is not that crazy if you think about it. Mind you I am not saying I fully subscribe to it, but I can see where they come from and why it is written.

When you get into serious tech diving you are increasing risks dramatically. Usually you have a ceiling (either physical and/or virtual), are at greater depth and work with more and more exotic gases and all that comes with it (hyp(er)oxia, MOD's, PPO2's, CO2, IBCD, PPN2 etc). There could be instances where even though you did plan for gas losses, you need to assess if giving your buddy gas is going to put yourself in a situation that will become irrecoverable. This is a decision all divers need to make, but it is more at the forefront with tech diving.

Look at an example with Don Shirley and David Shaw. Don went after David to try to rescue him, but after he started to have issues himself, he had to cut that decent off and take care of himself. While he did not per se have a gas volume issue, it does illustrate the mindset.

On paper we all can plan things, in reality at that crucial moment when it can quickly become a matter of living or suffering severe results, you decide and move on with your decision.

I think you have a good point. It's hard to place set in stone rules.

For instance, could you imagine trying to write in a textbook to spend __% of your gas completing a lost buddy drill in a cave? I mean logically, 1/3 of your gas is theirs, but if you're best friend/dive buddy's light was in the distance when you hit that 1/3, would you turn and leave him? If there's no signs of a buddy within a few minutes, would you continue to burn gas, check side tunnels, and deplete your gas reserves, or exit and hope your buddy does the same?

 

[Meng_Tze]

..... I mean logically, 1/3 of your gas is theirs,..

What if I say '1/3 is reserve' for whomever needs it. Does that change the decision you are about to make?

 

[ucfdiver]

What if I say '1/3 is reserve' for whomever needs it. Does that change the decision you are about to make?

Certainly....if I have a free flow or something, I WILL lose gas during a valve shutdown, and I have no buddy (in this case) to share air with to make up for it. If I think there's any hope of finding him, I'll try, but somewhere there has to be a cutoff line. If a training agency wants to write a set in stone limit, so be it, but I'm going to use logic over agency standards any day of the week.