Your Gradient Factors?

[PfcAJ]

I am pretty sure that in all my planning for technical dives in well over a decade, I have never been near a printer when the plans were made, let alone a laminator.

I have all my tables printed and laminated. It’s the only way to go.

Scribbling on a slate or wet notes page is for the birds.

Pick the relevant table and go. Easy.

 

[Blackcrusader]

I am sure they have those details. The article article gives enough information to get a good idea.

The DAN DB analysis shows that most dives were made in a “safe zone,” with an average depth of 27.1 m, average GF 0.66, and an average ascent speed lower than the currently recommended “safe” one. Even more importantly, very few deco omissions occurred; this indicates that divers tend to dive very conservatively.​

I have frequently heard or read the phantom statistic that 50% of all DCS cases happen when the diver is within NDLs. Well, in this study, 97.5% of all DCS cases occurred with the divers staying within NDLs. Apparently it is pretty rare for NDL divers to violate their computer algorithms, so the overwhelming majority of DCS cases occur within NDLs.

OK recreational divers staying within NDL and still having DCS... dang
I barely get to average 20m max on only a few dives my overall average is around 15.5m.
So I am doing recreational diving and often with OW certs staying at less than 20m as well. Never even had the tingles that I've seen a few instructors get when they pushed things on some 40m dives.

I assume the DAN DB is for those doing deep deco dives.

 

[boulderjohn]

OK recreational divers staying within NDL and still having DCS... dang
I barely get to average 20m max on only a few dives my overall average is around 15.5m.
So I am doing recreational diving and often with OW certs staying at less than 20m as well. Never even had the tingles that I've seen a few instructors get when they pushed things on some 40m dives.

I assume the DAN DB is for those doing deep deco dives.

No--there were all NDL dives.

Statistics can be funny. Yes, 97.5% of divers who got DCS were within NDLs, but means less than you might think. I am willing to bet that at least 97.5% of the people who die in China each year are Chinese, but that does not mean that it is especially dangerous to be Chinese in China. What they found was that almost everyone in their study was is a recreational diver stays within NDLs, so that is logical that pretty much everyone who got DCS was within NDLs.

 

[Blackcrusader]

No--there were all NDL dives.

Statistics can be funny. Yes, 97.5% of divers who got DCS were within NDLs, but means less than you might think. I am willing to bet that at least 97.5% of the people who die in China each year are Chinese, but that does not mean that it is especially dangerous to be Chinese in China. What they found was that almost everyone in their study was is a recreational diver stays within NDLs, so that is logical that pretty much everyone who got DCS was within NDLs.

DAN wrote very few deco omissions occurred so I am thinking ok these are deep deco dives.

27.1m average depth for that single dive where they got DCS over lots of different divers?
OK that I can understand but for a moment I was thinking how to you get a 27.1m depth average over say 20 or 30 dives and stay within NDL That's cause I am thinking of my 30 dives in 9 days back to back lol

even on a single dive with an average to 27.1m what do they do, go to 40m ride NDL back to 25m then shoot for the surface with the 5m 3 min safety stop added in?

 

[dmaziuk]

DAN wrote very few deco omissions occurred so I am thinking ok these are deep deco dives.

27.1m average depth for that single dive where they got DCS over lots of different divers?
OK that I can understand but for a moment I was thinking how to you get a 27.1m depth average over say 20 or 30 dives and stay within NDL That's cause I am thinking of my 30 dives in 9 days back to back lol

even on a single dive with an average to 27.1m what do they do, go to 40m ride NDL back to 25m then shoot for the surface with the 5m 3 min safety stop added in?

I remember now: they had 320 recorded DCS cases and table 4 has the statistical breakdown of all 308 of them. 2 of them had a back-calculated (from computer logs) GF > 1 -- at some point in the dive -- and the remaining 306/308 is the 97.5% who never exceeded Buhlmann's M-values.

I.e. what you're looking at is, if you got bent on a benign vacation dive, there's a 97.5% probability of your hit being "undeserved". It's the posterior probability after you're bent.

They also had a questionnaire filled in for 40,000 separate, as in no indication of any intersection with the 320 recorded DCS cases, vacation dives. That wasn't part of the statistics because the numbers not related in any way except that they're dives too.

 

[kensuf]

I have all my tables printed and laminated. It’s the only way to go.

Scribbling on a slate or wet notes page is for the birds.

Pick the relevant table and go. Easy.

And ya only gotta do this once. You can even include useful stuff like rock bottom and deco gas calcs on the table.

 

[jale]

And ya only gotta do this once. You can even include useful stuff like rock bottom and deco gas calcs on the table.

and after "some" dives you know the "memorable" numbers which give you access to all these laminated tables and beyond

 

[boulderjohn]

DAN wrote very few deco omissions occurred so I am thinking ok these are deep deco dives.

They have a list of the most common features of the divers and the dives that had the DCS, even for the most minor of commonalities. Required decompression is not listed at all, so it is hard to believe that they were all or nearly all decompression dives. You wolud think they would have noticed that commonality

 

[JonG1]

On the subject of tables to back-up a primary and secondary computer, I had a situation where my primary failed part way through deco (battery connection sheared), I routinely set my back-up to 90/90 to give me a "fast" option out of the water in the event of an issue requiring it.

I still had a HUD to monitor PPO2 but only the 90/90 ascent as opposed to my preferred ascent of 50/75. Having back-up tables in my wet notes allowed me to follow my preferred ascent accurately without having to resort to guesswork or padding.

The hard tables are cut with both a 50/75 ascent and a 90/90 ascent.

 

[helodriver87]

On the subject of tables to back-up a primary and secondary computer, I had a situation where my primary failed part way through deco (battery connection sheared), I routinely set my back-up to 90/90 to give me a "fast" option out of the water in the event of an issue requiring it.

I still had a HUD to monitor PPO2 but only the 90/90 ascent as opposed to my preferred ascent of 50/75. Having back-up tables in my wet notes allowed me to follow my preferred ascent accurately without having to resort to guesswork or padding.

The hard tables are cut with both a 50/75 ascent and a 90/90 ascent.

I run my computers at the same GF setting, but my emergency get out of the water fast plan has always been to use a combination of GF99 and SurfGF. Ascend until your GF99 hits 90, hold for a bit until you can ascend further, repeat until you hit your last stop, then hold until SurfGF hits 90. It's probably not as precise, but it would work.