Theorizing about scuba diving
What factors influence the probability of a dive leading to DCS? Many of us would love to know the answer to that question. Wouldn’t it be great if we had a huge database of dives with depth profiles and lots of additional data of many different divers, together with information if those dives led to … Continue reading "Statistics is hard to get right"
Let’s interrupt the regular program for a short commercial break: Veronika Sievers and Dominik Elsässer have turned their Punkfish online seminars into writing and finished a book on decompression theory: So far only in German, it covers everything from the basics to the latest findings. It should be accessible to all divers and different from … Continue reading "New decompression theory book"
In the past, I have talked about the poor empirical data underlying the NOAA limits for preventing CNS oxygen toxicity. Of course, those are tricky, since having a seizure at depth has a high likelihood of resulting in fatal outcomes while there are good chances that the diver has no way to see it coming. … Continue reading "CNS O2 Limit Updates"
On Thursday, I took my daughter to the movies and we watched “Mission Impossible 8: Final Reckoning” which as my dear readers will be aware of involves an extensive under water chapter. This leaves the theoretical diver with a number of questions regarding in particular the physics and diving shown. WARNING: Spoilers ahead! Tom Cruise … Continue reading "Questions after MI8: Final Reckoning"
I understand the kids today use generative AI for everything. So, it is just natural to use it to blend some diving gases as well. I already had my CGI script to compute how to top up your gases using Subsurface’s real gas approximation. Now, I played around with some large language models and Claude.ai … Continue reading "AI Real Gas Blending"
Here is an email I wrote to the Subsurface mailing list in response to the suggestion to offer the option to display gas use (SAC or RMV) in units of pressure drop per time even when you use only a single cylinder size: There are two separate issues: One is if you measure the gas … Continue reading "Don’t measure gas use as pressure drop per time"
Not a lot of new content here recently. The last days, I attended 37c3, the annual hacker convention of the Chaos Computer Club which took place again in Hamburg . So, today, we will have some engineering content rather than the usual physics one. You have to see the super entertaining talk by two guys … Continue reading "DIY Submarine"
It has been very quiet here for a while. That is partly because there is a topic that I wanted to discuss here and since my take was going to be at least somewhat problematic, I felt for a while that I needed to do more reading to get the facts right. But now the … Continue reading "Probabilistic decompression models: Probably problematic"
This post is a copy from an answer in the Subsurface support forum but I post it here as well as this point comes up over and over. It is about the setting of some dive computer where you can set the density of water or whether you are diving in sea or fresh water. … Continue reading "Salinity and water density"
As mentioned before, gases in diving cylinders are not only not sufficiently well approximated by the real gas equation but also the van der Waals equation, despite its prominence in thermodynamics teaching, is not doing much better. Subsurface does better than this using a polynomial fit to table data for the compressibility of the three … Continue reading "Blending real gases"