Rred
Contributor
Kel-
That's great, it sounds like that dive center is actually doing something in the name of safety rather than shearing the sheep. Even better if one of those computers in the bucket is one you are familiar with. Like the manuals say...don't dive with it till you understand it, right?(G)
I've never seen a boat say "Computers required, but we'll supply one if you don't have it." Just that they were required, which is tilted a bit towards a nasty parental attitude, telling the diver what, we're too stupid to use the tables if we choose to do it that way?
Even DAN will tell you, the USN tables are based on certain known percentages of DCS hits in a specific population group. And since the advent of computers, the percentage of hits in sport divers basically HAS NOT CHANGED, indicating that using the tables still does a job pretty well.
Are computers letting divers extend their bottom times? In theory, sure. In practice? Well, there's still only so much air you can stick in a bottle, and then you're into twin tanks and deco stops and more than just computers anyway. And once you get complicated enough, then sure, computers don't make little errors like "Ooops, I didn't carry the one." I don't think that's the bulk of the sport diving population though.
AFAIK the only rigorously performed and statistically valid studies are the ones done by the USN, who are mainly concerned with combat operations and young male divers in top physical shape. Apparently, in order to get statistically meaningful results, actual field results and not theories, you'd need to do something like 1000 dives by 20 year olds, another thousand by 40 year olds, another thousand by 60 year olds, or some similar extensive and expensive real world testing. [Translation: Ain't gonna happen.]
This is not to denigrate the theories and logic that people are applying, just saying there's a often big difference between "Wilbur, that ain't never gonna fly" and what really happens. Especially when the exact details of gas absorption and the body are still not totally understood. (Like, the role of changing blood vessel wall cells, which get smaller as you get older, and how those size changes apparently affect gas transport.)
Logically, sure, a longer shallow water safety stop (let's be honest, that's decompression) should give the body some time to off-gas at a gentler rate than direct surfacing. The big question being how much is enough and just how effective how much time or depth is, which is where the need for objective studies on large numbers of dives is needed. And, as they say, "economically unfeasible".
30-40 years ago US divers were taught to ascend straight up at 60fpm, and the "Club Med" system of ascending diagnonally (effectively slowing the ascent rate) was debated or poo-poo'd here. Today? 60fpm is like canyon jumping a rocket motorcycle, 30fpm is expected, and "not more than 30fpm" advised by a number of sources. (It would be nice if dive computers allowed us to program them for specific rates, maybe in five years, huh?)
That's great, it sounds like that dive center is actually doing something in the name of safety rather than shearing the sheep. Even better if one of those computers in the bucket is one you are familiar with. Like the manuals say...don't dive with it till you understand it, right?(G)
I've never seen a boat say "Computers required, but we'll supply one if you don't have it." Just that they were required, which is tilted a bit towards a nasty parental attitude, telling the diver what, we're too stupid to use the tables if we choose to do it that way?
Even DAN will tell you, the USN tables are based on certain known percentages of DCS hits in a specific population group. And since the advent of computers, the percentage of hits in sport divers basically HAS NOT CHANGED, indicating that using the tables still does a job pretty well.
Are computers letting divers extend their bottom times? In theory, sure. In practice? Well, there's still only so much air you can stick in a bottle, and then you're into twin tanks and deco stops and more than just computers anyway. And once you get complicated enough, then sure, computers don't make little errors like "Ooops, I didn't carry the one." I don't think that's the bulk of the sport diving population though.
AFAIK the only rigorously performed and statistically valid studies are the ones done by the USN, who are mainly concerned with combat operations and young male divers in top physical shape. Apparently, in order to get statistically meaningful results, actual field results and not theories, you'd need to do something like 1000 dives by 20 year olds, another thousand by 40 year olds, another thousand by 60 year olds, or some similar extensive and expensive real world testing. [Translation: Ain't gonna happen.]
This is not to denigrate the theories and logic that people are applying, just saying there's a often big difference between "Wilbur, that ain't never gonna fly" and what really happens. Especially when the exact details of gas absorption and the body are still not totally understood. (Like, the role of changing blood vessel wall cells, which get smaller as you get older, and how those size changes apparently affect gas transport.)
Logically, sure, a longer shallow water safety stop (let's be honest, that's decompression) should give the body some time to off-gas at a gentler rate than direct surfacing. The big question being how much is enough and just how effective how much time or depth is, which is where the need for objective studies on large numbers of dives is needed. And, as they say, "economically unfeasible".
30-40 years ago US divers were taught to ascend straight up at 60fpm, and the "Club Med" system of ascending diagnonally (effectively slowing the ascent rate) was debated or poo-poo'd here. Today? 60fpm is like canyon jumping a rocket motorcycle, 30fpm is expected, and "not more than 30fpm" advised by a number of sources. (It would be nice if dive computers allowed us to program them for specific rates, maybe in five years, huh?)
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