how to calculate where your first decompression stop is

[kaylee_ann]

I'm going to get crap for this. so much crap. why I decided to even post it, not totally sure, but nobody else would probably know but this forum. I've tried looking it up online and can't find really anything.

to preface this, it's only for brain exercise and academic purposes. I am NOT going to actually put this into practice. I just love to learn and know the mechanics behind decompression theory. always have, probably always will, BUT it does not mean I am doing it in real life. it's just for fun! I'd never actually do a decompression dive based on this.
oh eta- I'm not gonna teach anyone this either

so for academic purposes, how do you calculate where your first decompression stop is based on depth and time? I think you have to factor in estimated tissue loading, which the formulas are somewhere in Deco For Divers which I have. but I'm not sure how, once you get the number for that, to find your first stop. again, I'm absolutely NOT going to put this into practice! I just love to learn. it's nothing more than that, I swear.

anyway, is it even possible to calculate this? or am I dreaming up something that you can't really do? I'm sure there's a way since dive computers do it constantly. lots and lots of math though, I'd presume.

thanks to anyone who answers the question nicely

 

[rhwestfall]

I can't find the link, but a SB member ( @EFX ?) had a spreadsheet he put together. It would have the "maths" in it to look at...

Search for: "Dive Calculation Spreadsheet"

Last update was 5/30/2023

 

[L13]

Doing it by hand is almost impossible for all but the most simple dive profiles. Here a link to an overview of the basic idea. There is a lot more in a full up implementation.

DIY DECOMPRESSION

 

[happy-diver]

THE FIVE WAYPOINTS AND SIMPLE ASCENT BEHAVIOR

“You’ll always miss one hundred percent of the shots you don’t take.” Wayne Gretzky, the only NHL player to have his number (99) retired across the league – Born January 26, 1961 Wit…

decodoppler.wordpress.com

 

[BlueTrin]

You can implement Buhlman.

I had a go, here’s the repo if of any interest, I’d not use this for anything serious, it was not tested properly and I didn’t even try to do it seriously or in a clean manner:

GitHub: BlueTrin/diving_decompression/master

Click to run this interactive environment. From the Binder Project: Reproducible, sharable, interactive computing environments.

mybinder.org

 

[Still Kicking]

There used to be something called Ratio Deco -- a shorthand way to calculate stops; you can probably google the 'secret sauce" -- it worked but it has fallen out of favor. Now most people use tables or more commonly follow the computer.

 

[Lorenzoid]

Crikey, @BlueTrin. Anyone have it in, say, FORTRAN for geezers?

 

[andyrocks]

The simplest (and most limited) way is to use tables. Look up your depth and time on an appropriate table and it'll show you your deco stops or lack thereof.

 

[BlueTrin]

Crikey, @BlueTrin. Anyone have it in, say, FORTRAN for geezers?

I can give the chat GPT/Bing version

 

[LFMarm]

I'm going to get crap for this. so much crap. why I decided to even post it, not totally sure, but nobody else would probably know but this forum. I've tried looking it up online and can't find really anything.

to preface this, it's only for brain exercise and academic purposes. I am NOT going to actually put this into practice. I just love to learn and know the mechanics behind decompression theory. always have, probably always will, BUT it does not mean I am doing it in real life. it's just for fun! I'd never actually do a decompression dive based on this.
oh eta- I'm not gonna teach anyone this either

so for academic purposes, how do you calculate where your first decompression stop is based on depth and time? I think you have to factor in estimated tissue loading, which the formulas are somewhere in Deco For Divers which I have. but I'm not sure how, once you get the number for that, to find your first stop. again, I'm absolutely NOT going to put this into practice! I just love to learn. it's nothing more than that, I swear.

anyway, is it even possible to calculate this? or am I dreaming up something that you can't really do? I'm sure there's a way since dive computers do it constantly. lots and lots of math though, I'd presume.

thanks to anyone who answers the question nicely

It’s based on a model of how gas dissolved in tissues is released as your external pressure decreases. Quite hard to calculate without a software. Both tables and ratio deco are approximations based on square profiles and certain assumptions on conservatism, etc.

If it’s something you like to play with, you can install SubSurface and start testing dive profiles. Based on that you can also do your own regressions and built simplified formulas similar to ratio deco