The SAUL Dive Planner is Here

The SAUL dive planner is the first probabilistic dive planner available.  Deciding how to structure it took some time but, in the end, after considering more complex set-ups, I decided to keep the dive planner relatively simple.  There is a choice of breathing gas – air or 32 nitrox.   The dive profiles available are all square profile with specified descent and ascent rates (60 fsw/min) and include a mandatory 3 minute safety stop at 15 fsw.  There is a further choice of doing a “forward” or a “reverse” calculation.

In the “forward” calculation, you will input the maximum depth, and the maximum time you want to spend there.  The planner will output the probability of incurring decompression sickness for that dive (unlike currently available planners, which would either permit or not permit that dive).   In the dive planner’s forward calculation, if you should, in some instance, see the probability of decompression sickness shown as 0%, remember that this does not, of course, represent an absolute zero probability but 0% when the calculated probability is rounded to a finite number of figures.

In the “reverse” calculation, you will input your maximum acceptable P(DCS) along with the maximum depth, and the planner will provide you with the maximum bottom time to keep within your chosen P(DCS).  (So, the “reverse” calculation, after you choose your maximum acceptable P(DCS),  will give results in a style similar to currently available planners.)

Just a few reminders before we start:  There is always some possibility (even when very minimal) of decompression sickness when you dive.  You might want to reread the previous blog post on probability.   Because all the dive profiles included are square profiles with a stop, this is what they would look like in diagram form.



You may already know that, by definition, bottom time begins when you enter the water and ends when you begin your ascent.   Please realize as well that, with SAUL, the safety stop is an essential part of the calculations, as are the descent and ascent rates.  Any changes to these could affect the probabilities given.   In addition, these probabilities are for single dives only. Repetitive dives are not included in this version of the planner.

As you should be aware, a dive planner is only that.  It is not an adequate substitute for a dive computer.  This is true in general for all algorithms.  Because of SAUL’s greater accuracy and complexity, it is particularly true for SAUL.


To use the SAUL Dive Planner:



  1. Thanks for posting the planner, interesting to try out. I could not get 130 feet for 32% to do any calculations. Many algorithms have a slower ascent rate of 30 feet/min, or that rate when at 60 ft or less.

    It is difficult for me to interpret the probability of DCS. I ran all the DSAT NDLs between 60-120 feet for 32%. All probabilities ran between 0.27 and 0.46%

    Appreciatively, Craig

    • Thanks for your comment. I’m replying to your concerns in my next post (which will be up later today or tomorrow), as I think it may be of interest to others.

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