Have I understood the basics of decompression theory, GF99 and SurfGF?

[tursiops]

Well, I think you have things reversed. Copying experts (which I do myself) does not make you an expert. I was talking about people who are experts on their own otherwise demonstrated expertise, like Dr. Simon Mitchell.

Dang.

 

[Dan]

LOL.
And you are still refusing to take responsibility for possibly posting nonsense! How do you know, if all you do is repost something from ChapGPT?

I’m not refusing to take responsibility for possibly posting nonsense. I posted its answer here for the experts here to critique, discuss and educate me.

Did I say it’s right or wrong?

You said it’s possibly nonsense, without specifically pointing out which parts of its answer are possibly nonsense.

 

[Dan]

In the same article he says not to exceed GFHi=80. So what is the rationale in the posts above for 55/85? Seems like cherry picking various results to find the cherry you want. 55/80 would be Fraedrich's and would ignore David Doolette. Hmmm, who would I rather believe?

Shearwater uses GF Medium Conservative 40/85 as a default. If that’s risky, that’d be a lot of newbies would get DCS and open up liability situations.

 

[lowwall]

You are still dodging.

Why should other people be responsible for going through something you blindly posted?

LLMs are extremely good at creating sentences and paragraphs that look plausible, they are far less good at creating sentences and paragraphs that are 100% accurate and reliable.

 

[lowwall]

Shearwater uses GF Medium Conservative 40/85 as a default. If that’s risky, that’d be a lot of newbies would get DCS and open up liability situations.

Newbies are doing NDL dives. There is literally no difference between 40/85 and 85/85 if you are doing an NDL dive.

 

[scubadada]

That 55/85 pair is a well-regarded “medium-conservative” choice for a Teric when you want a bit more margin than the factory Medium (45/95) but without adding unnecessary time.”

AI often makes basic mistakes with information like saying 45/95 is the medium conservatism preset. When one has knowledge of a topic, these errors are quite obvious. It is interesting to point these errors out. A common response is something like, of course you are correct, my new answer is blah, blah, blah. To me, these basic errors simply point out that the entire answer is suspect for accuracy.

I also have come to enjoy asking AI questions. The answers are often good starting points for further research. Look at the references and expand your search to other sources. An additional strategy to using Google.

Like many of you here, I have used the information available to me and have chosen GF settings on my Teric. Everybody's diving is personal for them. Most of my dives are no stop but often are reasonably aggressive. About 5% of my dives are light back gas deco, generally <10 minutes. I have dived an Oceanic computer running DSAT since 2002, nearly 2500 dives. One of my current computers is still an Oceanic. I have been diving Buhlmann ZH-L16C with gradient factors since 2016, first with a Dive Rite Nitek Q and then my Teric in 2019, now more than 1300 dives.

So, based on the information available to me I have chosen GFs on my Teric that are good for me and my diving. I also use SurfGF to help guide my final ascents. Like @Dan, I have never had even a hint of DCS and wish to keep it that way.

 

[boulderjohn]

Shearwater uses GF Medium Conservative 40/85 as a default. If that’s risky, that’d be a lot of newbies would get DCS and open up liability situations.

Newbies are doing NDL dives. There is literally no difference between 40/85 and 85/85 if you are doing an NDL dive.

In addition to what Lowwall wrote, a GF low value of 40 is not exactly risky. For an NDL diver, it just isn't optimal. If the newbie were to go into deco by the little bit typical of a newbie who overstays NDL, a short stop--maybe a minute--deeper than normal might be required. Not only that, the algorithm would know that the deeper than necessary first stop required a slightly longer final stop and would adjust appropriately.

For longer, intentional decompression dives with a GF low of 40, the primary consequence is having to do longer shallow decompression, not getting DCS.

 

[dmaziuk]

In addition to what Lowwall wrote, a GF low value of 40 is not exactly risky. For an NDL diver, it just isn't optimal. If the newbie were to go into deco by the little bit typical of a newbie who overstays NDL, a short stop--maybe a minute--deeper than normal might be required. Not only that, the algorithm would know that the deeper than necessary first stop required a slightly longer final stop and would adjust appropriately.

As I recall back when @huwporter ran the numbers, you have to dive 10/90 to trigger a deco stop -- after "just" exceeding your NDL -- at 9 msw. For anything less silly you'll get at most 6 msw that is practically indistinguishalbe from the 5 msw where many of us are doing our safety stop anyway.

 

[MarkA]

Search Results for “fraedrich” – The Theoretical Diver

thetheoreticaldiver.org

Thank you for that. I seem to remember reading this in the past.

Seems to show a difference in GF if NDL or serious deco dives.

 

[inquis]

Seems to show a difference in GF if NDL or serious deco dives.

Buhlmann ZHL16 is known to not be iso-risk for a given GF setting as depth varies. Increasing the margin (GFHigh in particular) for deeper dives makes sense. DSAT has been tested for repetitive NDL and is approximated by a GFHigh of 95. There's no way I'm doing deco at that setting.