No Technical Training for Me.

[dumpsterDiver]

The dive was planned for a square profile of 160 ft for 30 minutes and that is what they did. I have read a lot about 80% and 100% arguments and I tend to agree with GUE on this issue, however 80% ain't gonna kill you any more than wearing the wrong kinda fins. The negative bouyancy issue is what really scares me, although they all were wearin double bladder BC's.

The instructor was taking the "other student" for a 180 ft (air) training dive sunday (the following day). I'm sure that went better.

 

[MikeFerrara]

The dive was planned for a square profile of 160 ft for 30 minutes and that is what they did. I have read a lot about 80% and 100% arguments and I tend to agree with GUE on this issue, however 80% ain't gonna kill you any more than wearing the wrong kinda fins. The negative bouyancy issue is what really scares me, although they all were wearin double bladder BC's.

The instructor was taking the "other student" for a 180 ft (air) training dive sunday (the following day). I'm sure that went better.

What agency is that? The only agency that I know of that permits training that deep on air is PSA (Hal Watts).

 

[ianr33]

What agency is that? The only agency that I know of that permits training that deep on air is PSA (Hal Watts).

TDI Extended Range certifies to 180 I believe.

 

[Gilldiver]

Perhaps the real reason some use 80% is that that is just about the highest O2% you can get in a 3000 psi bottle without a boster.

2200 psi O2 (standard max fill for most O2 storage tanks from gas suppliers) topped with 800 psi of air will gived you 80% O2.

Don't let anyone else BS you, if they are using 80% and don't have a booster it is the most they can get.

 

[Soggy]

80% is clearly on of those gasses that give divers bad bouyancy control...

I didn't use buoyancy control as a reason...

The rest of your "reasons" are only valid if you accept the premises that they are built on which is fine if your way of diving sets those premises in stone, the rest of the world is a bit more flexible...

Feel free to debate it. Good luck with that.

 

[Soggy]

Perhaps the real reason some use 80% is that that is just about the highest O2% you can get in a 3000 psi bottle without a boster.

2200 psi O2 (standard max fill for most O2 storage tanks from gas suppliers) topped with 800 psi of air will gived you 80% O2.

Don't let anyone else BS you, if they are using 80% and don't have a booster it is the most they can get.

That *would* be reason (not a good one), except that you also increase your gas requirements by decompressing at 30' rather than 20'.

 

[ianr33]

On O2, the O2 window is always wide open regardless of depth since there is no inert gas.

What do you mean by that? Would the window not be more open at 3 ATM O2? What is so magical about 1.6 ?? What does the oxygen window (or partial pressure vacancy) have to do with the presence or otherwise of inert gas?

Your post seems to rehash this infamous one http://www.subaqua.co.uk/reference/articles/bakers-dozen.shtml

Given the choice I would prefer to use 100% O2,but I dont think that 80% is the devil.

 

[Mr.X]

In any case...the training the diver was getting doesn't appear to be very good but his performance would sure indicate the need for LOTS of training. I think it's a good example of what would happen to a lot of divers if they tried a free ascent and had to do a few other things like shooting a bag and gas switches or whatever. The correct solution to bad training would seem to be good training...not no training.

I'll say this. After some experience teaching entry level technical courses and assisting with a few technical classes, I didn't have any trouble deciding NOT to become a technical instructor. From what I saw of it, recreational training just doesn't do a good job of preparing divers to even start technical training. You almost have to start a lot of them over from OW skills, because they either learned everything wrong or not at all.

As a tech instructor I'd like to say that there's an obvious need for vetting on both sides - instructor and student. Obviously, this wasn't the case in the posted scenario. The instructor needed some remediation...indicated by the fact he allowed a student to dive in OW using the mentioned config. The student(s) should have been referred to a Fundies Course where they got their buoyancy and equip. skills down pat before venturing into a deeper water training scenario. But hey, it really is up to the instructor to make sure there is a minimum level of diver competence before starting someone @ 160'.

If anything, the entry level tech students that I see are improving with regards to equipment config., but what I see lacking is actual in-time experience with buoyancy, swimming skills etc. As a caveat - I've seen HOG equipped divers screw up almost as much as stroke equipped diver because they thought gear was going to work wonders for them.

 

[Soggy]

What do you mean by that? Would the window not be more open at 3 ATM O2? What is so magical about 1.6 ?? What does the oxygen window (or partial pressure vacancy) have to do with the presence or otherwise of inert gas?

100% O2 is unique in that it has the same decompression efficiency regardless of depth. Running it deeper at 20' has a number of benefits relating to bubble formation, but if you run any profile, the sum of the 20' and the 10' stop will be the same as if you set your deco software to a last stop of 20'. Obviously, a 1.6 is "magical" because it is the highest PO2 we can 'safely' run as human beings. If we could decompress at a 2.8, that would be nice, but my life is too valuable to take that risk.

With 80% you are NEVER going to get the same decompression efficiency because there you can never get a better Pinert than 0!

I'm not going to write up another long drawn out , but this stuff should have been covered in anyone's adv nitrox class plus it's been rehashed a billion times already. 80% is just a ridiculous choice. I usually don't outright say that a gas selection is foolish, but this one is.

 

[MXGratefulDiver]

That cured me of wanting to be a "technical" diver for a few more years!

Well, it should just cure you of wanting to take technical instruction from that instructor ... mine wouldn't let a student in the water with a rig like you described, nor would he take you below 70 feet without first demonstrating solid basic skills.

... Bob (Grateful Diver)