"Riding your Computer Up" vs. "Lite Deco"

[DevonDiver]

If agencies provide a 'system', then the use of computers may pose risks of system breakdown.

As an example... training provision/qualification-level is typically balanced against formal limitations on the diver.

So... for a given agency we have an amount and standard of training (i.e. PADI OW and AOW syllabus) that was initially designed based upon the restrictions of diving within the agencies designated tables. This balance of training provision versus limitations ensured diver safety.

Those divers... receiving the same training syllabus.... nowadays don't dive with designated agency tables. They typically use computers. Those computers enable much more aggressive diving... or even empower divers to exceed no-stop limits (and can allow theoretical 'justification' of such behaviours).

This can be considered an imbalance between training and the limitations appropriate for that training.

Of course, agencies do teach 'use of diving computers', but not to the detail of algorithm behaviour and variances. Agencies generally keep it simple, advising students to "dive conservatively" etc, etc. ...advice which, I note, is selectively ignored by some.

Comparing one agency versus another is comparing apples to oranges. The single unifying factor is that agencies try to balance training they provide with appropriate limitations.

Differing agencies provide differing training... varied hours of study and practice... varied performance standards. Some are low commitment, others are high commitment. Student qualification limits are tailored accordingly.

BSAC tables might not be appropriate limitations for a PADI qualified diver who's done a quick certification course, nor vice-versa....PADI tables might be restrictive to a BSAC diver who's recieved significantly more volume of training (even when course levels are deemed equivalent).

Computers.... being of varied limitations... throw these balanced systems into confusion. It's entirely possible for divers to now set themselves very permissive limitations far beyond the capabilities and scope of their training.

The prudent solution is, of course, is for the diver to either self-select appropriate limitations for themselves... based on accurate reflection of the training heaven recieved and their real diving abilities (problematic and prone to over-zealous self-assessment).... or to seek further training that ensures they are appropriately and amply trained for the dives they wish to undertake.

 

[stuartv]

If agencies provide a 'system', then the use of computers may pose risks of system breakdown.

As an example... training provision/qualification-level is typically balanced against formal limitations on the diver.

Do you have any data to support the suggestion that there is an actual problem here, or is this more FUD?

 

[DevonDiver]

It's a thinking-point, or a logic persepective, not a theorem.

Why ask about statistics when anyone who's been on Scubaboard longer than a day knows that no comprehensive statistics are collated to profoundly support 99.9% of the theories or opinions voiced here?

What's "FUD"?

 

[lowviz]

If agencies provide a 'system', then the use of computers may pose risks of system breakdown. ...//...

That is a fresh thought!

Thank you.

Comparing one agency versus another is comparing apples to oranges.

I like to compare apples to oranges, mostly because I'm the guy who gets bent/embolized/killed. I never forget that.

Sometimes the apples want to get in five dives, sometimes the oranges are all about one single mission. Some agencies want to focus on bathwater McHappy Dives and others focus on the nastier stuff. I don't judge, I choose.

The prudent solution is, of course, is for the diver to either self-select appropriate limitations for themselves... ...//... or to seek further training ...

That must have been a difficult thing to write, as an instructor. I give you credit for your open-mindedness.

Yes, I believe that self-selected limitations (based on prior training/knowledge) can be a viable way to progress.

@KenGordon , Still working on an answer. -Wheels within wheels...



FUD: Fear, Uncertainty, and Doubt. Like when someone says "Oh, you bought a (insert anything)? Interesting....

 

[stuartv]

What's "FUD"?

Fear, Uncertainty, and Doubt.

If I say, Trump may initiate a nuclear strike the day after he's inaugurated, that is FUD.

When you say:

If agencies provide a 'system', then the use of computers may pose risks of system breakdown.

And you don't have data to support that that notion MAY be true (that use of computers may pose the risk you mentioned), it strikes me as being in the same family as the Trump example I gave.

 

[KenGordon]

.
The (presumably) quite rare cases of a diver getting hurt because they got too close to their NDL and freaked out don't seem (in my relatively uneducated on the statistics mind) to merit making any changes to the way things are done. People are not getting hurt because of that particular issue in any remotely meaningful numbers (I don't think).

If dives choose to use longer NDL times because they are not trained to do deco then they will be getting out of the water with higher N2 loading than if they had done the same dive but with some computer imposed stops.

You can see this effect widely on SB where computers configured to give shorter NDLs are slated as limiting bottom time. Really though the difference is the couple of minutes of stops that the conservative computer would have given for the same bottom time. Given a large enough sample of dives that will increase the number of bends happening.

 

[MXGratefulDiver]

So, buy a DSAT computer if you don't want your dives cut shorter than they have to be, while staying with the bounds of your training.

... or stay within your training, and if you want to extend your dives beyond that, seek more training.

I get the gist of what you're saying and tend to agree with it ... but playing with NDL is like playing with fire ... it's only "safe" if you understand what you're doing.

Bigger concerns for me would be having a basic understanding of how to manage your ascent profile when pushing the limits of NDL ... and making sure you have plenty of gas to not only handle the ascent properly, but deal with any potential emergencies that might arise. That entails either having a buddy you can trust and adequate reserves between you to maintain an orderly ascent, complete with any stops needed to honor your obligation, or carrying a redundant air supply. There's also a mindset requirement ... if you're going to push NDL's, don't be in a hurry to get to the surface. In a properly managed "lite deco" situation, you should have honored any obligation by the time you reach your safety stop depth.

... Bob (Grateful Diver)

 

[Storker]

In violation of what YOU initially chose before the splash. Well stated, NDL is a limit. It has to be a hard, exact, and well-defined limit or we can blow it off and continue to rationalize further and further unsanctioned forays into deco land.

I tried to say roughly the same back in post #69

Anything else would be starting to normalize deviance.

 

[stuartv]

... or stay within your training

My post that you quoted IS staying within OW training.

 

[lowviz]

I tried to say roughly the same back in post #69

Yes, you did.

But what I thought that I was hearing was that there is only one NDL, the one imposed by the agency that taught you. @DevonDiver pointed out that picking and choosing DC's for longer bottom time effectively breaks your training.

I think you ought to completely explain what you mean about a choice of NDL. I think I know what you mean - being which tissue code you come out at, but you might mean which table you start with.

You are correct, I can control the tissue code. The NDL is indeed no-deco, but the limit is now the tissue code that I want to control.

This is the part that I love about the BSAC presentation. There are no RNT calculations necessary and far fewer tissue codes. I find subsequent dive planning to be far more obvious when using the rather large collection of level and tissue loading tables. Please correct me if I'm wrong, but it looks to me like there are absolutely no calculations needed with the BSAC 88 approach.

As to your premise... you are essentially diving the navy tables but usually taking a longer ascent by your computer.

Yes, exactly. And the "lite deco" part of it is the difference between me and a highly fit 19 year old. I plan to keep nipping back from the navy tables as the years roll by.

Another, rather easier to justify in my opinion, way to the same thing is to have two plans with MultiDeco. One is the bail out no stop plan, the other the plan to actually dive. This way you can set likely ascent rates. If your bail out assumes an AS ascent with a buddy it is unlikely to be as per the specified navy rate.

Interesting idea, I'll have to play with that.

BTW, the tables do not teach how to do these dives. The lectures and open water lessons do that. The tables do have the information about how to drive the tables though. It is moderately complicated so the tables contain instructions. I would be genuinely interested to know if you can figure out how to do the altitude planning, and especially travel after diving, from the instructions.

The first thing that I did when I got my booklet was to read the series of increasingly complex sample dives. In all honesty, I could follow them but I was unsure if I could properly generate them on my own. I then went to the last three pages and studied the Surface Interval Table, Transfer Table, and the Altitude/Atmospheric Pressure Chart. It all made sense then. The only flub was not noticing that the altitude chart was corrected to sea level and all of the pressures on the multitude of tables were local pressures at elevation.

One can also get tripped up by not paying attention to the barometric pressure (even at sea level) or not picking the correct surface interval table. I suppose that the most complicated thing is travel to altitude without making a dive and then returning. One returns with a tissue loading.

Of course if you want to have proper fun you should order the Nitrox tables and the Ox-Stop (accelerated deco) tables. The latter are particularly entertaining.

I found the air tables amusing enough, thank you.