Phil K.:
This unfortunate statement from the author of this thread clearly shows how Meng-Tze has been poorly served by a supposedly DIR forum. The last thing that we should be doing here is giving the appearance of managing a diver's risk of DCS based on methods that amouint to "black magic" or rely on a "lucky shot." Wrong wrong wrong attitude.
RD has it's place in a dive planning protocol, but it's value is in it's utility, assuming a dive plan that falls within its constraints, i.e. it's ease of application, not in it's own independently proven scientific validity, because all the anecdotal evidence aside, it has no proven validitity except to the extent that under its constraints it approxoimates other algorithims that have been subjected to rigorous testing and peer review. If you attack the validity of all other algorithms, you also undermine RD's own validity. It is important to harmonize the best available DCS predictive tools, which aren't coming out of Monterey; but Durham, NC and a few other laboratories and universities around the world; and making prudent judgements based on the requirements of a proposed dive and the specific situation. RD cannot stand alone if all other approaches are relegated to junk science. Without that connection, there's little wonder that the average reasonable person would think of decompression planning as "black magic."
Buhlmann has "scientific validity" but no one wants to actually dive a profile that it spits out. Buhlmann bent people left and right and had to incorporate a cosmological hemilum constant, oi vey. Nobody's doing those profiles - not without extensive modification at least.
RD has no peer-reviewed "scientific validity" but generates profiles quite similar to those people actually want to dive. And it incorporates concepts that people know work but can't quite mathematically figure out. Deep stops and O2 windows for instance. Also people are diving profiles similar to RD profiles every day. 1000s of successful deco profiles. And they are way more similar
in their totality than a Buhlmann or VPM profile.
So hold up one of your recent deco schedules Phil or Milo. What's it look like?
Here one of mine:
150ft depth, 21/35+50%, fresh water temp =43F, air temp ~40F
BT = 27 mins
10-8
20-6
30-3
40-2
50-2
60-3
70-3
80-1
90-1
100-1
110-0.5
Worked fine, no fatigue or other issues. Buhlmann says I should be bent like a prezel cause I didn't even start off-gassing according to him until 35ft or so. Yet I live on.
And this isn't the only one, I have dozens more in the 140-165ft range. I'm T1 so those are the limits of my experience. And really any plan is only as good as your experience with it.
As I said earlier, I would use decoplanner as a sanity check on a 70 min 100ft dive with O2 for deco. Why? Because: 1) I don't plan dives there very often and want to double check my math 2) I want to have a rough idea what my "bailout" is. That is if I have to blow off deco where does Buhlmann have me doing deco and why? 3) Since I have little experience on a dive like this I want to have every tool in my toolbox out for inspection. But no I'm not putting alot of faith in the decoplanner profile, nor really the total stop time since it will be missing pieces.
Personally, I do view deco science as black magic. Esp. since all the "scientifically valid" methods either bend and mend, don't work, make you feel horrible, etc. I'll take methods which get me out of the water feeling like 100 bucks over theoretical science every day.
aranoid: , please let me know if you find any...
