Adv Nitrox/Deco Procedures

[texdiveguy]

When I started into technical diving I had been already doing serious sport diving and so that did help some know doubt. I did not have the advantage of an Intro to Tech course available to me at the time---probably if I had I would probably have taken it (they sound good for those getting started). I really enjoyed my TDI Advanced Nitrox and Decompression Procedures courses....they were informative and the dives educational and a bit challenging. I persl. think these two type courses are the fundamentals to building on for more advanced technical diving. I don't feel these or any level of recreational tech needs to be taught in the 'boot camp' style...but in a serious/challenging and enjoyable format to really be most effective. Each subsequent TDI technical program I took was a bit tougher and more challenging, Advanced Trimix is an intense but exciting program with a great sense of accomplishment. Like I mentioned, I think Advanced Nitrox and Deco Proc. courses are the building blocks that all advanced tech diving rests on regardless of the discipline(s) you choice.

 

[TSandM]

So it sounds as though Advanced Nitrox is a little like Fundies? Managing buoyancy under task loading, air-sharing while maintaining buoyancy, shooting a bag?

What about deco procedures?

 

[Dive-aholic]

One of the best things I learned in Advanced Nitrox was how to shoot a lift bag. We did our open water dives in 5 foot visibility above 30 feet, so being able to shoot a lift bag and do your stops gave me a lot of confidence in low vis.

We had to shoot lift bags, too...after a cave dive. TDI really needs to produce a cave version of this class.

Besides shooting bags, we had to swim a certain distance underwater to our buddy in an OOA simulation. I don't remember the distance, but it was quite a bit. I almost didn't make it! We also worked on valve drills. The primary focus of the course, though, was planning and execution. We planned our dives according to SAC and air supply, worked out deco schedule, and went diving according to plan. You don't realize how difficult it can be to stick to a schedule when you're task loading. Ascent with several stops and air switches, shoot a lift bag enroute. I think we also had to buddy breathe our O2. I'm sure there were a few other things I'm forgetting.


Deco Procedures was the planning and execution part.

 

[wedivebc]

So it sounds as though Advanced Nitrox is a little like Fundies? Managing buoyancy under task loading, air-sharing while maintaining buoyancy, shooting a bag?

What about deco procedures?

Actually what has been described above is more like an instructor's variant of the course. Lift bag skills are usually part of deco procedures and since the adv nitrox and deco porc are most often taught together it is difficult for the student to differentiate between the two. TDI requires a members login to view the standards much to my chagrin so I can not send you a link. If anyone knows of a TDI standards posted elsewhere Lynne should check them or PM me your email address and I will send you a copy.

 

[texdiveguy]

TDI in a nut shell, most instructors add to these, I know mine did.

"Advanced Nitrox course......The TDI Advanced Nitrox course is for those divers who want to optimize their gas mixes when planning dives up 150ft. During the course you will be taught how to effectively use EANx 21 through 100% oxygen.

The main objective is to train divers in the benefits, hazards and proper procedures for utilizing 21-100% oxygen for dives NOT requiring staged decompression.
Required Subject Areas:

1. Physics – review on pressure
2. Physiology- review of hypoxia, oxygen toxicity (whole body/out's, CNS toxicity), nitrogen narcosis, nitrogen absorption and elimination, carbon dioxide toxicity, carbon monoxide toxicity
3. Formula work-best mix calculations, MOD for mix calculations
4. Equipment considerations- up to 40% and above 40% use of oxygen
5. Dive tables-EAD use with any table, computer generated tables
6. Dive computers-air, nitrox and multi gas
7. Dive planning-Operational: gas requirements, O2 limitations, Nitrogen limitations
8. Common mixing procedures-Partial pressure, continuous blending, membrane separation system
9. Decompression-EANx usage as a deco gas, 100% O2 for deco, Advantage/disadvantages of multiple gas switches.

Required Open Water Skills:

1. Properly analyze gas mixtures
2. Demonstrate adequate pre-dive planning; Limits based on personal gas consumption, limits based on O2 exposure at planned depth, limits based on nitrogen absorption at planned depth with actual mix

Decompression Procedures course......This course examines the theory, methods and procedures of planned stage decompression diving. It is designed as a stand-alone course or it may be taught in conjunction with such TDI courses as Advanced Nitrox, Advanced Wreck, or Extended Range.The main objective is to train divers how to plan and conduct a standard staged decompression dive not exceeding the maximum depth of 150 fsw unless taught in conjunction with the TDI Advanced Nitrox, Extended Range or Advanced Wreck courses. The most common equipment requirements/configurations, gear set-ups, decompression techniques and decompression mixtures are presented.
Required Subject areas:

1. Overview of decompression "safety stops" compared to required stops.
2. Physics-pressure review, formulas for solving dive planning, MOD, Best Mix, etc.
3. Physiology-Mechanics of bubble formation, Oxygen toxicity (whole body-out's and CNS), advantage of hyperoxic mixes for decompression, Nitrogen absorption and elimination, Carbon Dioxide Toxicity, Ascent/Descent rates, Hyperthermia, Hypothermia, Psychological aspects-task loading, stress, panic, time management, equipment.
4. Decompression Options- air, nitrox, oxygen, air breaks during deco
5. Equipment considerations-twin cylinder or single cylinder option, valve options. Stage cylinder options, regulator options, harness/BCD options, computer, depth gauge, bottom timer options, ascent and navigations reels, lift nags/surface marker buoys for drifting or free deco, jon-lines or Garvin clips, proper weighting and buoyancy control during dive phase and deco.
6. Dive tables vs. Computer-Intro and review of different models, proper use of electronic multi level computers for dive planning and deco, mix adjustable, O2 integrated, Deco planning software use.
7. Dive planning-standard operation, gas requirements, oxygen limitations, and nitrogen limitations. Emergency planning-omitted deco, oxygen toxicity, DCS/DCI, equipment failure.
8. Procedures
* Primary and decompression gas-normal operations, failure, loss or inadequate emergency procedures. Analysis and logging. Safeguards and deco supply regulators. Rigging and deployment of deco gear.
* Descent-Methods of entry, down lines or free descent. Organization of equipment carried by a diver.Ascent-variable rates. Trim and buoyancy compensation.
* Fixed or Drifting Deco methods- up lines fixed to bottom. Reels and lift bags/surface marker buoys. Free drifting stages or live boat supply. Self contained versus surface supply/rendezvous gas cylinders.
* Support-From shore. From descent line or fixed platform. From live boat.

Required Open Water Skills:

1. Properly analyze all gas mixtures and label cylinders accordingly.
2. Demonstrate adequate pre-dive planning-Limits based on personal and team gas consumption. Exact dive and decompression profiles.
3. Properly execute the planned dive within all pre-determined limits- Assembly of diver carried equipment. Proper descent/ascent rates. Proper staged stop procedures. Monitoring of decompression status equipment (tables, computers, other equipment).
4. Contingency Situation & Problem Solving-Omitted decompression. Extended bottom time profiles with increased decompression and re-calculated schedules. Failure to deploy lift bag and reel. Missed up-line or missed boat anchor. Loss of decompression gas.
5. A safety stop of at least three minutes shall be conducted on all no-decompression dives and proper staged decompression stops whenever and wherever mandated.
6. Demonstrate the correct deployment of a lift bag using a dive reel and/or up-line.
7. Demonstrate (simulated) emergency gas sharing at a stationary depth not to exceed 100 fsw or a PO2 of 1.6ATA.
8. Demonstrate emergency deployment of a backup regulator or bailout scuba system containing bottom mix at a depth not exceeding 100 fsw or a PO2 of 1.6ATA.
9. Demonstrate the proper deployment, management and use of the bottom mix; decompression mix and travel mix if used. Conservative gas management. Depth control to avoid descending to deep for mix. Show appropriate and timely responses to instruction/signals form the instructor and demonstrate buoyancy control and awareness throughout the dive."

 

[matt_unique]

It has been a few years but lot's of valve drills, lot's of bag shooting, lot's of air sharing, simulated deco stops, switching between deco bottles and back-gas, all in awful (low vis/cold) conditions at least with my course.

The first class session emphasized gear and gear setup (i.e. how your recreational rig is not going to cut it). Lot's of classroom time on SAC calculations and dive planning. The instructor had us do exercises (underwater) to get actual consumption rates to be used for the SAC calculations. (Volume consumed over X minutes doing a hard swim, at rest, and normal cruising rates).

For my last dive the instructor said I had completed everything necessary for the course but wanted to add a few dimensions. In 37 degree black water he wanted me to remove my mask, remove my deco bottle, follow a line 30' out and 30' back, find and reattach my deco bottle, then put my mask back on. I admit I could not do it at the time....Prior to this course I had not done much work with mask off drills. I could not "equalize" my breathing for lack of a better expression in the 37 degree water. After a minute or two I put my mask back on and signaled I was having trouble with it. I was very frustrated but it was a great lesson in what I needed to work on. Ever since that dive I have made a point to a.) carry a 2nd mask for deep dives b.) regularly practice breathing with my mask off, and c.) practice removing my primary mask and switching over to my backup mask. I also make a point to practice valve drills and bag shooting on a regular basis.

Slightly off topic, I don't think it's a realistic or even workable solution for anyone to do 45 minutes of deco sans mask in cold water. IF you had a buddy with the exact same deco obligation and gas mixes they could help you with your gas switches and ascent rates and the whole 9 yards. Without a buddy I think it would be nearly impossible. To have all this combined with a painful ice cream headache? Forget it....you need a backup mask.

 

[Tienuts]

Sorry but I am not a fan of causing problems for yourself during a dive just to see if you can handle it, especially when you are already in an overhead type environment whether physical or virtual from deco obligation. That being said my Deco proceedures class was all about proceedures and less about makeing trouble.

Now why would you not want this?

Suppose you are on a dive with a deco obligation, and you have a failure? Multiple failures? How will you react? Anyone can follow a printed run-time and do a deep dive when things go right. Its when things go wrong people get killed.

When I seek out an instructor for a class, I want the guy/gal who will torture me with failures - to stress me and task load me so I can learn from my mistakes. Also to build muscle memory so when all goes to hell in a handbasket at 300 feet, I know I have a good chance of living.

 

[wedivebc]

Now why would you not want this?

Suppose you are on a dive with a deco obligation, and you have a failure? Multiple failures? How will you react? Anyone can follow a printed run-time and do a deep dive when things go right. Its when things go wrong people get killed.

When I seek out an instructor for a class, I want the guy/gal who will torture me with failures - to stress me and task load me so I can learn from my mistakes. Also to build muscle memory so when all goes to hell in a handbasket at 300 feet, I know I have a good chance of living.

I have been harrassed in training and I have had training that contained a minimal of skills and I have to say I felt I got more of the training with greater challenges. To that end I am an opportunistic harrassment facilitator. If my students are dangling things or have hoses sticking out they will get tangled. If they have their secondary hose improperly stowed they will have a primary failure etc. I make the harrasment plausable. Lost mask/fin/deco bottle all at once is not realistic and borderline sadistic. If the student is too harrased they just get either angry or exasperated and in either case don't seem to learn as much.

 

[pir8]

I believe in practice and drill, not creating problems that aren't there.

 

[matt_unique]

I'm not a proponent of "surprise" training either. I don't think it serves any real purpose for an instructor to sneak up behind you and take your mask and turn your air off for example. This would probably serve a useful purpose for Navy Seals or something.