Extended rec diving as intro to tec

[AndyNZ]

I've just started looking at taking some tec diving courses (most likely TDI Adv Nitrox & Deco) as a means of starting to extend my diving beyond rec limits.

I don't want to rush into buying a whole new load of tec gear at this stage, and probably won't for a while after the course and will want to try lots of different configurations and options before parting with hard earned $$$s.

I currently dive with a single tank BPW and am thinking of taking the course using this and a side slung stage tank. Is this likely to cause problems on the course? It's probably representative of how I'm likely to dive for a while and I'm used to having a bailout tank on my left anyway.

Knowing that Adv Nitrox & Deco is really an introduction to tec, how are things like valvvle drills etc going to be affected by this configuration?

Just want to gauge opinions before talking about this issue with the two instructors I could take the course with, partly as a way of helping to decide which one to go for.

[StagRaven]

I would think that at a minimum, intro deco will require doubles. Adv. nitrox may or may not, depending on the instructor. Even if not required, though, why not get some more in-water with them? Practice never hurts!

[AndyNZ]

Twins are the way to go longer term, but right now I can't afford a new wing, tanks, bands, manifold etc. I also don't know how much technical diving I might do to justify the outlay.

TDI seem to be a bit more flexible in terms of gear configuration than DSAT, GUE etc. Any comments?

[lostplanetairman]

Its hard to do deco on singles in that you'd run out of gas before encountering the NDL limits. But there nothing wrong with getting a pony ( 30cu + ) and slinging it. For now its good for a bailout bottle and it'll make a great deco bottle later. Maybe your instuctor can let you try set of doubles, if not rent them for the course. I do the Adv.Nitrox/Deco theory in 2 weeks.

[AndyNZ]

But there nothing wrong with getting a pony ( 30cu + ) and slinging it. For now its good for a bailout bottle and it'll make a great deco bottle later.

This is pretty much how I dive now, with the pony either being a bailout or on occasions taken with a higher nitrox mix for more conservative safety stops.

Before I get flamed, yes I am aware that the second case loses redundancy... ;)

I figure that I'm likely to do some diving to extend bottom time with in rec depth limits, maybe using different mixes in back gas, one stage tank and a deco tank.

[StagRaven]

Ok, just on a quick search I found this:

The following equipment is required for each student:
29. Primary Cylinder(s). Cylinder volume appropriate for planned dive and student gas
consumption.
30. Decompression Mix Cylinder(s)
A. Cylinder volume appropriate for the planned dive and student gas consumption
with submersible pressure gauge.
B. Labeled in accordance with TDI Standards.

Also, the following is the applicable training standard. It would also seem to allow a single tank and stage.
54. Demonstrate the proper deployment, management and use of the bottom mix,
decompression mix and travel mix (if used)...

From this, I would say that if the depths and profiles presented can be met with a single and a slung stage, then the instructor would not be averse to allowing them. Hope this helps.

The full course outline can be found here: http://www.deco-stop.com/Decompression%20Procedures%20Course%20requirements .pdf

[AndyNZ]

Thanks, Josh. That's really useful.

[Tavi]

Usually the Instuctor have equipment requirements. Talk to them.

[matt_unique]

You will have to demonstrate isolating a malfunctioning reg through valve drills in the course. This can be done on singles with an H or Y valve.

I took Deco Procedures on single steel 120's with H and Y valves. I paid attention to the process for those on doubles because I planned to get a doubles rig within a few months. I then took Adv. Nitrox with the doubles and of course had to demonstrate everything learned in Deco Procedures with this rig. An important lesson learned from Deco Procedures was how woefully inadequate recreational gear is for tech diving (i.e. singles, BC, etc.)

So in short it can be done with a min of an H or Y valve. You may feel differently about a singles setup through the process of your course.

Deco Procedures is the single best course I have taken to date (out of 13 or so).

--Matt

[DA Aquamaster]

I took TDI Deco Procedures and Advanced Nitrox together with a diver in the class who used a 100 cu ft tank with a regular K-valve and a 40 cu ft deco bottle. The course standards allow a diver to do this, but again the gas supply has to be adequate and the instructor has to be in agreement with it as well.

Personally, I would have preferred that everyone in the class dove with doubles as it would have allowed longer dives and run times. As it was, the instructor padded things a bit for the single tank diver (who also had a higher than expected SAC) by having the single tank diver share air with me (and my doubles) pretty extensively during the dives.

So I guess, it's a case of you could do it, but the rest of the class may end up resenting you a bit unless you rent or own a REALLY big tank.

[roturner]

Knowing that Adv Nitrox & Deco is really an introduction to tec, how are things like valvvle drills etc going to be affected by this configuration?


In IANTD you wouldn't be able to take the course with a K valve but you can get away with taking the course using a single tank like a 120 with a Y valve. It makes the valve drills a little harder but they can be done.

R..

[AndyNZ]

Thanks, guys. Bottom time on a single isn't going to be too much of an issue - at 35m (110' or so) my dives are nearly always ended by NDL, not air. If I take the course, it's also going to be 1:1.

If I can borrow a twin set up then I probably will, with a view to buying later.