On Planning a SAUL Dive Planner

Okay, I’m finally ready to start working on the long-delayed SAUL dive planner.

As I mentioned briefly in an earlier post, I had been working on a book with two other authors – one of them a math/physics/chemistry type like myself, and the other an anaesthesiologist/hyperbaric medicine physician. Perhaps not surprisingly, writing the book took much more of my time, and lasted longer than I had anticipated.  The book, “Gas Bubble Dynamics in the Human Body”, by Saul Goldman, Juan Manuel Solano-Altamirano, and Kenneth M. LeDez is published by Elsevier/Academic Press, and you can find it by clicking on the book title, or by entering ISBN 9780128105191 on your web browser. It’s aimed primarily at researchers and graduate students in the sciences, and medical doctors (anesthesiologists, hyperbaric medicine and emergency medicine physicians).  But there is a long chapter on decompression models which details the scientific underpinnings of SAUL that will be of interest to SCUBA divers, and another chapter on arterial gas emboli (AGEs) in breath-hold diving that will be of particular interest to breath-hold divers.


On Planning a SAUL Dive Planner:

Complete details have not been finalized yet, but some initial decisions were made.  Two things it will not be – It won’t be in the form of dive tables, and it won’t be downloadable for use.  Two things it will be – It will be useable online.  And it will be, at least initially, free.

Figuring out the best way to set up a SAUL dive planner is more complicated than for currently used deterministic algorithms, because it’s probability-based.  This means that there are many more questions you could ask.

For example, let’s consider a simple square-profile, such as is done on a wreck dive. Let’s assume the wreck is level, and you know its depth, so the question is about how much time you may have to explore it. Other algorithms will give you a definite maximum time (the “NDL”) for that depth. With SAUL, however, there are (at least) two ways to approach the question. You could first decide on a personal acceptable level of DCS risk (e.g. P(DCS) < 0.001 ), and from that point, using it like any other dive planner, ask how long you can stay at that depth without exceeding that risk. But another approach would be to think about a range of possible bottom times spent at the depth of the wreck, and ask what your risk of DCS would be if you were to stay for different lengths of time at the wreck’s depth.

True, that’s only two different ways – rather than “many” – of asking the question in that simple example. But dives being planned are often not that simple.  When you consider repetitive and/or multilevel dives, forward and reverse dive profiles, multi-day diving, and breathing gas choices (air/nitrox), the number of ways you can approach the dive planning process, as well as the numbers of questions you can ask, increases considerably.

Ideally, it should be possible to use the SAUL dive planner for any type of question or approach in dive planning.    I will try to make its overall use as simple as I can, but, for this to happen, it would help if I had some input from potential users as to how they might want to use it. I’m not going to ask you to fill out a survey, but if any of you would like to comment on how likely you might be to use the SAUL dive planner in specific different diving situations, I’d appreciate it. As a starting point I’m listing a number of obvious scenarios, but I welcome your suggested additions and elaborations.

  1. a) a single recreational low-risk profile – either square or multi-level – with a safety stop, on air or nitrox.
  2. b) repetitive recreational low-risk square profiles with a safety stop, on air or nitrox.
  3. c) forward and reverse multilevel dive profiles with a safety stop, on air or nitrox.
  4. d) multi-day diving based on the above profiles, on air or nitrox.
  5. e) a single high-risk decompression dive on air – at most one dive per the day.


While I’m working on getting the SAUL dive planner ready, I will also try to start posting again on a somewhat regular basis. If you’re familiar with this blog, you’ll know that, for me, a regular basis is still not very frequent, but the most recent very long gap has been largely because of the book.

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