A recent comment on my The Doctor is In Part IV blog post, followed by a more detailed letter to me raised some issues that need to be addressed.  The comment read as follows:

SAUL sounds like a giant leap forward in dive safety and one that will always be attributed to the brain work of Dr Saul Goldman. As far as I understand however a route has been chosen to make the invention a proprietary solution, which is an unbelievable shame. Have you considered to make this algorithm available to the public domain so that *every* dive computer manufacturer can implement it, including those that do not want to be involved in the proprietary IP madness of this world. What if Einstein had taken a patent on all his inventions? What’s more important: A bank account or saving lives?

The writer refers to my making SAUL “a proprietary solution”.  This is not exactly the case.  SAUL – or, more accurately, the model upon which it is based – is patented.  What’s the difference?  A proprietary solution is generally kept secret, because, not being patented, secrecy is often the only way to protect it from being “stolen” by others.  A patent provides its own legal protection, is not secret, and, in fact, is published online by the U.S. Patent Office.  In addition to that, my article in Journal of Physiology (which can be downloaded from the Articles section) contains details of my model.

The two main objections the writer seems to have to what he calls a “proprietary solution” are: first, that he would like every dive computer manufacturer to be able to implement it, and, secondly, some apparent distaste for my wanting to make money from it.

I have no problem with the first objection.  In fact, it is my goal and my expectation that  every dive computer manufacturer will eventually implement it.  I have no intention of selling exclusive rights to a single manufacturer, nor have I ever considered doing so.  SAUL was, and is, my way of giving something back to the diving community for all the enjoyment I have had, and continue to have from diving.

So, why do I not overcome the second objection by putting it in the public domain (or, as one computer manufacture I approached put it, “make it open source, like Buhlman”.)?   Perhaps I would – if computer manufacturers offered their products for free, mechanics repaired cars for free, airlines gave free flights, etc. – but I don’t really see that happening.

I spent years of my life, and a fair amount of my own money, developing SAUL and, while I’m not looking to get rich from it, there’s no way I will allow computer manufacturers to profit from it without my profiting as well.

There’s also a secondary reason I won’t make it open source:  The model underlying SAUL is different from, and more complex mathematically than, Haldane-based models (which includes all the others out there, including so-called “bubble-based” ones).  I have some concerns about the potential for people with insufficient mathematical and scientific skills trying to “adapt” or change the algorithm.

In his longer letter to me, the writer mentions some objections he has heard from dive computer manufacturers he queried: specifically, that they were either “unaware of” SAUL or that it was “untested”.  I can’t speak to whether any of them are actually unaware of SAUL (although I have my doubts).   SAUL is also no less “tested” – in a formal sense – than are any of the algorithms in use today.  While dive computer manufacturers do  test their computers before their release, they do not test the accuracy of the algorithm.  What they test is, essentially, the functioning of the hardware and the software environment – in other words, that the computer is actually doing what the algorithm tells it to do.

As far as being tested, the largest body of test data in existence was amassed in an extensive series of experiments conducted by the U.S. Navy, in conjunction with the Canadian Navy and the (British) Royal Navy.  Real-life testing to that same degree can’t  be done by anyone nowadays –  not even by the Navy  (some of it would never pass an ethics committee).  These provide the data that all algorithms use, either directly or indirectly, as they calibrate their equations to fit, as best they can, the known facts.  (In the case of SAUL, I had access to that entire data set and used it extensively.)   To the best of my knowledge and belief, SAUL’s predictions fit the Navy data better than any other algorithm.  I have also been given access to a large portion of the recreational dive data collected by DAN in their Project Dive Exploration.  SAUL predicted the actual incidence of decompression sickness in those dives very accurately, much more so than typical Haldane based algorithms whose predictions were too high by a factor of 10 or more.  SAUL is also the only model to account for the beneficial effect of safety stops and slow ascents.

It’s also worth mentioning, that I have given about 20 invited talks about on my model and related subjects to audiences composed variously of physicians, scientists, and divers.  I have spoken at meetings of the Undersea Hyperbaric Medicine Society (UHMS), American Academy of Underwater Sciences (AAUS), Canadian Association of Underwater Sciences (CAUS), South Pacific Underwater Medicine Society (SPUMS), and the International Congress on Hyperbaric Medicine (ICHM).   Of all the questions I was asked following these talks, the single most common one was “When will this be available in a dive computer?”  So far, I haven’t been able to provide a definitive answer to that question, but I’m still trying.