Question How to Calculate First and Final Stop Depths When Implementing Gradient Factors in Bühlmann ZHL-16C?

[bernatrubio]

I’m coding a dive computer algorithm using Bühlmann’s ZHL-16C model. So far, I’ve implemented it successfully without incorporating any conservatism. Now, I want to add Gradient Factors (GF). My main reference is Erik C. Baker’s article "Clearing Up the Confusion About 'Deep Stops'".

In the formula presented, I need to calculate the GF slope, which depends on GF_High, GF_Low, the First Stop Depth, and the Final Stop Depth. My question is: How should I calculate the Final Stop Depth and First Stop Depth while considering GF_High and GF_Low?

 

[bernatrubio]

Sure, I would be open to a video conference. I have zoom and can use other software as long as it runs on Linux. Even though you are responding in English I have to state up front that I do not speak or understand Spanish. Furthermore, any information or advice I give you is solely based on books, articles, and what I've received from papers from Erik Baker and others that are in the public domain. I have not communicated with nor have I been given any information from commercial vendors of computer decompression software that has had any significant impact on the software that I have written. I only state this so there are no misunderstandings going forward.

So, with that disclaimer out of the way let me know how we can proceed.

Thank you for your response and for clarifying everything. Zoom works perfectly for me. Please let me know your availability so we can coordinate. You can reach me directly at bernatrubio.scubaboard@gmail.com to discuss this further in private.

 

[dmaziuk]

I’m coding a dive computer algorithm using Bühlmann’s ZHL-16C model. So far, I’ve implemented it successfully without incorporating any conservatism. Now, I want to add Gradient Factors (GF). My main reference is Erik C. Baker’s article "Clearing Up the Confusion About 'Deep Stops'".

In the formula presented, I need to calculate the GF slope, which depends on GF_High, GF_Low, the First Stop Depth, and the Final Stop Depth. My question is: How should I calculate the Final Stop Depth and First Stop Depth while considering GF_High and GF_Low?

First you figure out if you have a stop, i.e. if Buhlmann's formula gives you a ceiling below the surface, using GF High for the surfacing GF. It's up to you whether to round any ceiling down to 3 msw or start at e.g. 1.5 msw (i.e. < 1.5 msw = no ceiling).

Once you have a ceiling, you recalculate using GF Low. That's your first stop depth.

If you have more than one stop, you have the GF slope between the first stop and the surfacing GF.