John_B
Grasshopper
But then we'd need inputs on how well they were hydrated on the flight down yesterday, and how many beers they had at the bar once they arrived, and how much REM sleep they got last night, and what is their actual body fat ratio, and do they have good air consumption, and how much of that is due to their higher-than-necessary metabolism (because they fin and skull their hands like crazy), and how much do they bounce around all over the water column vs. just hovering at depth, and any number of other factors I can't think of off the top of my head.But if we really knew under what precise circumstances a particular diver doing real-world multilevel dives would develop DCS with a high degree of accuracy, and if you could measure all the related parameters, and if you had a computer that could factor in all the realtime data and crunch out a genuine NDL number, then why wouldn't you be able to "ride" that number? Aside from reserving some amount for contingency, you wouldn't need to worry about it.
But right now that's all some sci-fi future; we have to deal with the imprecision of what we have now, goats and pigs and bent Navy recruits and all.
So we're never going to get something exactly precise that a new diver is going to be just follow with the brain cells in neutral and "guarantee" (in the legal sense) that they aren't going to get themselves bent.
Worse, due to those legalities we get a bunch of dive computers with a bunch of extra conservatism built-in. And how that conservatism is calculated becomes this big, proprietary, trade secret for each computer; sometimes even with a mathematician (cough, cough, Wienke, cough) as a paid endorser.
And eventually these new divers become convinced that simply flying these "conservative" PDCs to the NDL with no dive planning will "keep them safe" or "keep them from being bent".
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I reached a point where I will only dive with/buddy up a new diver if I've been able to have a discussion about buddy diving and basic gas planning. I guess if PADI is going to punt on this (and it sounds like they already have) then I'll have to add basic dive planning to that discussion. I hope it's a long enough boat ride out to the dive site.