how to calculate where your first decompression stop is

[EFX]

Yes. The spreadsheet is designed to mimic dive decompression software. It is designed as an educational tool with no safety warnings. It also does calculations for ppO2, NDL, ceiling, END, EAD, density, ICD, and gas usage. It supports up to five dive profiles which can be linked together to provide up to 20 stops for a single dive. Two main gases using nitrogen and/or helium as well as two deco gases are supported plus more. Check it out at HOME | My Site. Download the Scuba Dive Excel Spreadsheet.

 

[LFMarm]

Yes. The spreadsheet is designed to mimic dive decompression software. It is designed as an educational tool with no safety warnings. It also does calculations for ppO2, NDL, ceiling, END, EAD, density, ICD, and gas usage. It supports up to five dive profiles which can be linked together to provide up to 20 stops for a single dive. Two main gases using nitrogen and/or helium as well as two deco gases are supported plus more. Check it out at HOME | My Site. Download the Scuba Dive Excel Spreadsheet.

I just went through it and it's an incredible piece of work! It really shows that it has been refined over many years. I find particularly interesting the calculation of GF when going at altitude. I want to use it to check what the typical recommendation of 24h before flying and repetitive diving within NDL with commercially available computers (e.g., Suunto) corresponds in terms of GF. I am pretty sure that deco diving with a very long final deco may be safer before flying than some of those recreational profiles.

If you ever want to take it up another notch (not that you need to), it would be great to have a CCR options where you fix your pO2 to 2 setpoints. I guess it would be easier than current implementation as you need now to calculate pO2 for every depth.

 

[EFX]

Thanks. It took me at least five years to get it close to what it is now, and I credit a few key people for helping me along the way. I have been working on a newer version to calculate a continuous ascent to the surface for deco dives. Unfortunately, because of all the additions in new features over the years it has become very kludgy in some sections. I wrote a C program that essentially displays the dive profiles in the same output you see in Excel without the cells of course, as a terminal application. The code is much cleaner and easier to understand and as a result far easier to add new features. In fact, I added the continuous ascent on deco to this program and it appears to work correctly (there is a minor problem I need to fix). Anyway, I'm seriously thinking of rewriting the VBA code within the spreadsheet using the code from the C program. Hopefully, if I can work up enough energy I might actually get started on it.

 

[LFMarm]

Huge kudos!

 

[L13]

I just went through it and it's an incredible piece of work! It really shows that it has been refined over many years. I find particularly interesting the calculation of GF when going at altitude. I want to use it to check what the typical recommendation of 24h before flying and repetitive diving within NDL with commercially available computers (e.g., Suunto) corresponds in terms of GF. I am pretty sure that deco diving with a very long final deco may be safer before flying than some of those recreational profiles.

In general, there would be no advantage from deco for no fly. If you use the same GF's, your deco profile will have the limiting tissue be a slower time constant tissue than the NDL dive.

If you do extra deco, with a high %O2, you could accelerate the reduction of fly risk. However, you could also do this just as well or better by breathing the high %O2 on the surface. The change in no fly time would probably be no more than of 2x-3x the amount of extra deco time.

 

[LFMarm]

In general, there would be no advantage from deco for no fly. If you use the same GF's, your deco profile will have the limiting tissue be a slower time constant tissue than the NDL dive.

If you do extra deco, with a high %O2, you could accelerate the reduction of fly risk. However, you could also do this just as well or better by breathing the high %O2 on the surface. The change in no fly time would probably be no more than of 2x-3x the amount of extra deco time.

Great point on O2 at surface – I will test that one as well.

My point is that I am pretty sure (but will be able to quantify) that having a low GF-Hi on big deco dives creates lower risk for DCS from flying than following the recommended standards for multi-day NDL diving.

 

[L13]

Great point on O2 at surface – I will test that one as well.

My point is that I am pretty sure (but will be able to quantify) that having a low GF-Hi on big deco dives creates lower risk for DCS from flying than following the recommended standards for multi-day NDL diving.

Depends on the GF you use for calculating your NDL's. If it is the the same low GF-Hi, then no.

The longer the deco dives, the bigger the TC difference, and the lower the deco GF-Hi vs the NDL GF-Hi would have to be to see an advantage.

 

[LFMarm]

Depends on the GF you use for calculating your NDL's. If it is the the same low GF-Hi, then no.

The longer the deco dives, the bigger the TC difference, and the lower the deco GF-Hi vs the NDL GF-Hi would have to be to see an advantage.

For sure but Suunto RGBM with normal conservatism is much more aggressive than my typical GF.

 

[jamesnvc]

Anyway, I'm seriously thinking of rewriting the VBA code within the spreadsheet using the code from the C program. Hopefully, if I can work up enough energy I might actually get started on it.

Might be feasible to compile it to WebAssembly via emscripten and then be able to embed it anywhere that takes javascript - browser, Google Sheets spreadsheets, Postgres database...that way you just have the one codebase and don't have to port the logic back and forth between VB & C as you continue to make changes?

 

[dmaziuk]

gotta wonder what reason one could possibly have for embedding a pile of javascrapt in a postgres database...