TDI Advanced Nitrox / Decompression

[jdevic]

If you want to go into deco do it, there's no scuba police stopping you
I wouldn't go sucking on 100% without proper training though.
Sounds like you've already made up your mind you don't want to do any courses.

I still wouldn't mind doing ANDP - maybe I will try doing it in Chuuk next year in case I get bored with the wrecks

 

[wedivebc]

I(e.g. single tank; 10-15 min max in deco) and/or (less likely) use 80%-100% O2 for accelerated deco stops (hanging off a boat), how much training do I really need?
.

That sentence alone tells me that you should get training.

 

[dewdropsonrosa]

Speaking from the perspective of having completed AN/DP six weeks ago, you really do need the full extent of both classes' theory and practical training to be safe. Decompression diving is a much more complex game to play.

Fully appreciating, planning for, and assuming the risks of decompression requires understanding of gas kinetics and behavior, human physiology and compressed gases, gas planning, underwater problem-solving due to the 'soft' overhead, rescue skills and decision-making, on top of highly polished diving skills.

On your hypothetical dive:

• Do you know how long that single tank will last you at your target depth? Do you have the information you need to calculate that?
• Can this dive even be safely completed on a single tank? Where's your redundancy?
• Do you know how much deco gas you'll need to breathe? How much you'll need to bring for contingencies?
• Do you know the MODs of all your gases and when you can safely make switches? Do you know the procedure to make a safe switch?
• Do you know how you'll need to modify your decompression schedule if you're delayed in returning to the surface? If you come back sooner? Without blindly trusting your computer?
• Have you considered environmental hazards (temperature, surface conditions, changes in weather) for the extended duration of your dive?

Most OW training doesn't prepare divers to do this. I wasn't prepared to do it before I took the class. Technical diving requires technical training!

 

[Doby45]

I wouldn't go sucking on 100% without proper training though.

Without AN/DP it is difficult to get 100% O2 in reputable places. Are there places you could walk in and ask to have a 40 bottle filled with O2 and no one would bat an eye, sure. But, the majority will ask for a card for a 100% O2 fill.

 

[KentB]

(e.g. single tank; 10-15 min max in deco) and/or (less likely) use 80%-100% O2 for accelerated deco stops (hanging off a boat), how much training do I really need?

this is a terrible idea.

get some training.
I actually really really enjoyed it, and my skill level jumped dramatically.

my ANDP course was $1200 CAD for training. books, fills, boat and cert fees all extra. we did 10 dives. ranging from 60 min to 90 min. we did 4 days of boat diving so I think all said and done with books boat and cert fees and fills i was in the $1700 range. for sure its on the more expensive end here locally but I feel I definitely got my money's worth.

Instructor didn't require ITT first but asked how long we had been diving sidemount and how many dives we had and bottom time ect. and said lets do a checkout dive and would let us know if we were ready to proceed or not. he said course is minimum 6 dives most classes run 8-14 depending on beginning skill set. he charges 3-400 per extra day if you screw around and no show, ect but said if you don't we go until you're squared away and good to go for no additional charges.
Im currently doing Extended Range with him learning how to handle / use 2 deco gases.
In Hindsight I wish Id gone to BM instead of doing it in SM, I just don't have the gas Id like for bottom times.

When I did my side mount course from single tank back mount I was all " omg all this gas is great!" first tech course 4-5 months later its "damnit need more gas!"

 

[wedivebc]

So here's a likely scenario. You have a single tank of air and a bottle of O2 hanging off the boat. You look at you computer that tells you that you have 10min of deco and start making your way back to the boat. The current is against you and you are breathing heavy while looking for the anchor line and now you have to surface because you breathed the last of your single tank but the 10 min O2 deco becomes 20 min since you never got on the O2. You are now going to visit the chamber and the $30k you paid for the chamber ride makes you wish you'd spent $1k on training.
This is not that far fetched. If you want to deco dive get training. The saying "you don't know what you don't know" is not just a cliche'

 

[CAPTAIN SINBAD]

Adding, Pavao (above) got to watch my students doing their deco yesterday. One of them even did a Gator Chomp.

Nice. Which one of these is you?

 

[kensuf]

Second from the left, gray dive rite fins.