fsardone
Solo Diver
Hello everyone,
This post more than asking a question or providing an answer to the subject topic, is a pause of reflection upon the issue and maybe provide an initiating seed for some useful discussion.
We usually hear saying plan your dive and dive your plan and in Tech diving to plan we do use decompression software on which we rely. Also one of the no-no of (technical) diving is no trust me dives (dives in which we are diving beyond our level of training/knowledge/confidence). This notwithstanding we entrust our deco profile to something we do not fully understand “trusting” that those who wrote the software do understand them and follow best practices.
So are we ok in trusting such software? If yes why (no betters alternative)? If not why do we do it?
From my point of view there are 3 classes of software:
Commercially developed by a company that is in deco is line of business (dive computer manufacturers). These are closed architecture, take it as it is, in some cases limited in term of gases, or platforms, depth ranges or available algorithms. Backed by the company philosophy on deco, but with limited external scrutiny. Here, in my view righteously or not, the trust is in the company’s name.
Commercially developed by a small software house which does that as a primary product, closed architecture, with a lot of feature, cross platform, with no external scrutiny. Here, in my view, the trust is in the software house showing capability to ensure software correctness.
Open source software that while developed by a small number of people, is available in source format to the scrutiny of a large audience of programmers and divers. Examples of these are Subsurface (dive log and planning tool) and OSTC (Open Source Tag Computer) a diving computer, which allows you to load you own software and makes their own available in source format.
None of the above do research and experimentation to my knowledge, in the field of decompression. That is the realm of Navies (probably one Navy only has the budget to do it properly) and scholars in the field. Some is covered by patents.
Recent evolution of the mainstream thought about decompression, and ensuing discussions, made me wonder what would be needed to “trust” diving software (and implicitly the people who write and test said software). Do we trust the software implementation of the algorithm? Do we trust that the line depicting the maximum allowable supersaturation in ZHL-16C/GF is correctly interpolated from GF low to GF high? Do we trust the correct implementation of floating point math in a microcomputer for VPM computationally heavy calculations? Do we trust that whoever is it implementing the algorithm is using recognized best practices both in computer software development and decompression research?
I am not here to try to single out any of the available software or recommend one over the other but what should we be asking of those manufacturers? We ask scientists to be peer reviewed and the scientific methods require a thesis a supporting arguments and validating experiences. We need to be able to predict reality from our thesis. The scientific method can only disprove thesis but cannot ever prove them 100%. Theories that were tought correct for decades if not centuries had been proven wrong by improvement of our capability to assess reality. I could discuss Newtonian mechanics vs restricted relativity vs general relativity but I would end up off topic and people have written books about it.
So how would we want the software manufacturer to reassure us they are using the best available methodology to calculate a safe ascent? How would we want change in knowledge to propagate in best practices and in products? Is the software we are using inherently safe?
The floor is yours
This post more than asking a question or providing an answer to the subject topic, is a pause of reflection upon the issue and maybe provide an initiating seed for some useful discussion.
We usually hear saying plan your dive and dive your plan and in Tech diving to plan we do use decompression software on which we rely. Also one of the no-no of (technical) diving is no trust me dives (dives in which we are diving beyond our level of training/knowledge/confidence). This notwithstanding we entrust our deco profile to something we do not fully understand “trusting” that those who wrote the software do understand them and follow best practices.
So are we ok in trusting such software? If yes why (no betters alternative)? If not why do we do it?
From my point of view there are 3 classes of software:
Commercially developed by a company that is in deco is line of business (dive computer manufacturers). These are closed architecture, take it as it is, in some cases limited in term of gases, or platforms, depth ranges or available algorithms. Backed by the company philosophy on deco, but with limited external scrutiny. Here, in my view righteously or not, the trust is in the company’s name.
Commercially developed by a small software house which does that as a primary product, closed architecture, with a lot of feature, cross platform, with no external scrutiny. Here, in my view, the trust is in the software house showing capability to ensure software correctness.
Open source software that while developed by a small number of people, is available in source format to the scrutiny of a large audience of programmers and divers. Examples of these are Subsurface (dive log and planning tool) and OSTC (Open Source Tag Computer) a diving computer, which allows you to load you own software and makes their own available in source format.
None of the above do research and experimentation to my knowledge, in the field of decompression. That is the realm of Navies (probably one Navy only has the budget to do it properly) and scholars in the field. Some is covered by patents.
Recent evolution of the mainstream thought about decompression, and ensuing discussions, made me wonder what would be needed to “trust” diving software (and implicitly the people who write and test said software). Do we trust the software implementation of the algorithm? Do we trust that the line depicting the maximum allowable supersaturation in ZHL-16C/GF is correctly interpolated from GF low to GF high? Do we trust the correct implementation of floating point math in a microcomputer for VPM computationally heavy calculations? Do we trust that whoever is it implementing the algorithm is using recognized best practices both in computer software development and decompression research?
I am not here to try to single out any of the available software or recommend one over the other but what should we be asking of those manufacturers? We ask scientists to be peer reviewed and the scientific methods require a thesis a supporting arguments and validating experiences. We need to be able to predict reality from our thesis. The scientific method can only disprove thesis but cannot ever prove them 100%. Theories that were tought correct for decades if not centuries had been proven wrong by improvement of our capability to assess reality. I could discuss Newtonian mechanics vs restricted relativity vs general relativity but I would end up off topic and people have written books about it.
So how would we want the software manufacturer to reassure us they are using the best available methodology to calculate a safe ascent? How would we want change in knowledge to propagate in best practices and in products? Is the software we are using inherently safe?
The floor is yours