Another algorithm question...

[Ghost95]

Hello all. I'm looking at two different computers. One is running the DSAT algorithm and the other is PZ+.

I see allot about diving multiple days on live aboard type multi level profiles but I don't see allot of talk about square profiles.

In the northern gulf we bounce sometimes but usually it's hit the water, swim down, burn air and time, come up, wait and repeat. No real multi level stuff.

Are either one of these algorithms designed for that type of diving or are they both about the same?

Thanks.

 

[dmaziuk]

DSAT considers the 60-minute tissue compartment the most important for repetitive dives. (And comes with the "no more than 4 tanks/day, no more that 6 days in a row caveat.) Nobody knows what PZ+ does, but assuming it doesn't deviate from a ZHL-16 too far, it should give more weight to "slower" tissue compartments.

As a result DSAT should tolerate shorter surface intervals. However, there's no telling how many of those it'd take for PZ+ to show noticeable difference in its calculated residual gas loading.

That is assuming both use the exact same M-values (and that includes "safety" "conservatism" "gradient factor" modifiers). If not, the one with lower M-values should calculate shorter no-stop times regardless.

 

[MargaritaMike]

DSAT considers the 60-minute tissue compartment the most important for repetitive dives. (And comes with the "no more than 4 tanks/day, no more that 6 days in a row caveat.) Nobody knows what PZ+ does, but assuming it doesn't deviate from a ZHL-16 too far, it should give more weight to "slower" tissue compartments.

As a result DSAT should tolerate shorter surface intervals. However, there's no telling how many of those it'd take for PZ+ to show noticeable difference in its calculated residual gas loading.

That is assuming both use the exact same M-values (and that includes "safety" "conservatism" "gradient factor" modifiers). If not, the one with lower M-values should calculate shorter no-stop times regardless.

Now I'm really confused. I thought I knew the general difference, but now I'm not so sure. What is the effect on Day 4 of 2 tank recreational NDL dives to 100' then 50' with 60 minute SI on Nitrox 32 and 36?

Or does it matter?

I dive a Buhlmann ZHL-16 with a PZ+ backup. This isn't the OP's question, but your answer doesn't seem to answer it (at least in my diminished mental capacity).

**** Mod: Feel free to delete this post (as you have done before) if it doesn't state my question adequately or if my question is too far off topic - M²

Cheers -

 

[scubadada]

DSAT was mainly developed for no-stop dives within recreational limits. In validation testing, there was one case of DCS when diving 6 dives per day. The remaining validation dives were 4 dives/day, with no additional episodes of DCS. DSAT is on the liberal end of the spectrum. DSAT/PADI RDP have now been dived for more than 30 years.

PZ+ is a proprietary version of Buhlmann ZH-L16C developed by Pelagic Pressure Systems. The alterations are not in the public domain. The algorithm is middle of the road in the spectrum.

 

[dmaziuk]

Now I'm really confused. I thought I knew the general difference, but now I'm not so sure. What is the effect on Day 4 of 2 tank recreational NDL dives to 100' then 50' with 60 minute SI on Nitrox 32 and 36?

DSAT report I read said "air" so I've no idea what might happen if you breathe EAN 36 during SIs. Plus, if you're not diving to the NDL and not SI'ing to the exact number in Table 2, then you're not exactly diving DSAT, are you?

I don't think it's worth obsessing over. Take e.g. the grey cells where RDP says "optional stop required". You can program the computer with M-values "to the left" of those, so when it gets to 0 NDL, it'll have a couple of minutes of "safety stop required" before it gets into "deco stop required". Or you can program the M-values all the way to black cell and assume, like tables do, that when user gets to 0 NDL they will not skip the no-longer optional safety stop.

Exact same algorithm, 2 minutes difference in calculated NDL on the very first dive of the very first day.

 

[MargaritaMike]

That's funny!!!! I need to work on my sentence construction. The rest of the post is appreciated. Thank you.

Cheers -

 

[dmaziuk]

Where it does matter is a) if you skip the no-longer-optional-safety stop, implementation #1 will go into "missed deco" lock out. And b) if you dive with scubanazis who won't limit the total runtime but will instead insist on "no deco" and will watch your computer all the time throughout the dive.

 

[Ghost95]

Ok, my type of diving is usually square profiles, 70-100', nitrox, once or twice a week.

I'm looking at the VEO 2.0 with it's dual algorithm and a Genesis React Pro with a single algorithm. Does the dual algorithm make it worth the extra money for the VEO 2.0 for the kind of dives I described. (In your opinions of course)

 

[scubadada]

Ok, my type of diving is usually square profiles, 70-100', nitrox, once or twice a week.

I'm looking at the VEO 2.0 with it's dual algorithm and a Genesis React Pro with a single algorithm. Does the dual algorithm make it worth the extra money for the VEO 2.0 for the kind of dives I described. (In your opinions of course)

Hi @Ghost

The Oceanic Veo 2 and the Genesis React Pro are essentially the same 2 button computer made by Pelagic Pressure Systems. Main difference is Veo 2 runs DSAT and PZ+, React Pro runs only DSAT. What deco algorithm do you dive now? If you need only DSAT, either computer would be fine for you.

I have experience only with Oceanic/Huish, service has been good. The prices are not much different. Veo 2 is currently on sale for $240, React Pro appears to be $200, maybe $20 for the wrist boot. Either would require cable if you wish to download to your computer

 

[Ghost95]

Currently, I'm kind of diving an Orca Skinny Dipper MKII. Kind of using tables.

I'm no longer 25 and fit, more along the lines of 40 and, well, the things that go with being 40, so the MKII it's a little aggressive.

Both these algorithms seen to be a step back from that one.