Pelagic Pressure Systems Decompression Algorithms?

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scubadada

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Pelagic Pressure Systems was part of American Underwater Products (Oceanic, Aeris, Hollis, PPS...) until it was acquired by Aqua Lung in 2015. PPS has two decompression algorithms, DSAT and PZ+. Oceanic computers have run both algorithms, "dual algorithm", since PZ+ was introduced. There was no change after Oceanic was acquired by Huish Outdoors in 2017.

Does anyone know why all the Aqua Lung computers run only PZ+? Is there something preventing them from running DSAT or was it simply their choice to run the more conservative algorithm?

Of note, there are still a few other PPS manufactured computers that run one of the two algorithms. Sherwood and older Genesis computers run DSAT, while older Tusa computers run PZ+
 
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scubadada

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ask aqualung usa's in-house general counsel
Thanks, I've already contacted both Aqua Lung and Oceanic/Huish. I heard back from Huish nearly immediately. They believe Oceanic had rights to "dual algorithm" and that Aqua Lung chose PZ+ because it was most similar to Suunto RGBM that they were familiar with. We'll see if I hear back from Aqua Lung, I hope so.
 

MargaritaMike

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Hollis DG-03 runs PZ+. I ran it in parallel with my Perdix and they were fairly close on most of my dive profiles with the Perdix set conservatively. Since they were both AI it worked out nicely.

Cheers,
 
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I'm a little surprised, I was sure that someone on SB would know the story behind Aqua Lung running PZ+. I have not heard from Aqua Lung on the issue but still hope to.
 

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All Hollis computers ran PZ+
I haven't owned all Hollis computers, so I only commented on the one that I know about.
 
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I haven't owned all Hollis computers, so I only commented on the one that I know about.
What I said about Hollis computers above is not accurate. The DG01, DG02, and DG03 all ran PZ+. They had a tech model, DG05, that ran a derivative of Bulhlmann ZH-L16 with an adjustment different than GFs. It had an option for another algorithm they called Varying Gradient Model (no, not VPM). Their TX1 ran Buhlmann ZH-L16C with GFs. Hollis no longer has any computers.
 

stuartv

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AUP may have sold PPS but retained exclusive rights to DSAT, in order to maintain a competitive advantage with their actual computers. In addition to what was said about having the rights to "Dual Algorithm" (which may or may not be the case - Ratio does also have dual algorithms in their tech computers and I doubt they are paying any royalties to AUP).

The real question I wonder about is why AL (or any other mainstream, recreational sport dive computer manufacturer) doesn't have an option for Buhlmann w/GF.
 
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Thanks for the reply @stuartv

I did not hear back from Aqua Lung, so don't know their side of it. That is really the information I wanted, why they run PZ+

I thought about a potential rights to DSAT issue, but couldn't necessarily make it work out right in my mind. If rights to DSAT did not go with PPS, they may have belonged to AUP/Oceanic/Aeris and could have gone along with the sale of Oceanic to Huish. However, Sherwood and Genesis were allowed to run DSAT on their branded computers from PPS. Some of these models are still offered. "Dual algorithm" is trademarked by AUP/Oceanic/Aeris, though others like Ratio, Shearwater run 2 algorithms, Buhlmann and VPM.

Diving Science and Technology Corp. (DSAT) was a corporate affiliate of PADI and developed the deco algorithm for the PADI Recreational Dive Planner (RDP). This became available around 1987. I don't know how the computer version of this algorithm got to AUP/Oceanic, but Oceanic computers have been running it at least since the early/mid 1990s, perhaps earlier. I could not find any computer manuals prior to that time.

Truthfully, I thought these were probably pretty easy questions for some of the folks on SB. I guess I am not the only one who does not know the answers.

Good question regarding implementing Buhlmann more widely, perhaps the brands would lose their uniqueness? Crest and Atmos have both introduced computers running Buhlmann
 
https://www.shearwater.com/products/swift/

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