Perdix Ndls

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yes and no. If you are diving square profiles, then they should be within a minute or so of each other, but what doesn't change is the fact that the DSAT algorithm puts you at the surface with the same theoretical tissue loading as the computer, which may or may not be safe for repetitive diving, adverse conditions, etc etc.
 
I think it is possible that Ken misread the thread and assumed that the reference to PADI meant the diver was using tables rather than a computer using the DSAT algorithm upon which the PADI tables are based.
 
I read it assuming he was checking NDL times on tables vs Geo vs Perdix using the dive planner functions, hence a "square" profile for all three.
 
I read it assuming he was checking NDL times on tables vs Geo vs Perdix using the dive planner functions, hence a "square" profile for all three.
What I meant is i plan most my dives using the dive tables Supplied by Padi and also use my GEO 2.0. I mainly stick to my computer. Now I have a few dozen dives with this computer on pretty liberal settings according to others and what my manual states. I just got a Perdix and I see (at least for the first dive) that even set on low conservatism it is still more conservative compared to my tables, geo 2.0 and my friends suuntos. From what I read this is normal and has to do with GF and such which I'm starting to read up on. I was simply trying to ask if setting my computer to low would "theoretically be safe" since I have always felt fine using my more liberal GEO 2.0 dive computer? Some recommended starting on medium and going from there. Again just trying to learn and get an idea about this new computer. This will only be fore recreational dives. My largest concern is the first dive times the perdix was giving being quite a bit less than what I currently dive.
 
The profiles generated live by a computer are not always the same as those generated by a planner or a table. That is why there is a different set of coefficients for ZHL-16C and B. If you got a bunch of people doing dives without the 'free' conservation caused by the assumed square profile, rounded maximum depths and so forth they would, on average, get bent more often.

Maybe DSAT is different and doesn't account for this issue.
 
What I meant is i plan most my dives using the dive tables Supplied by Padi and also use my GEO 2.0. I mainly stick to my computer. Now I have a few dozen dives with this computer on pretty liberal settings according to others and what my manual states. I just got a Perdix and I see (at least for the first dive) that even set on low conservatism it is still more conservative compared to my tables, geo 2.0 and my friends suuntos. From what I read this is normal and has to do with GF and such which I'm starting to read up on. I was simply trying to ask if setting my computer to low would "theoretically be safe" since I have always felt fine using my more liberal GEO 2.0 dive computer? Some recommended starting on medium and going from there. Again just trying to learn and get an idea about this new computer. This will only be fore recreational dives. My largest concern is the first dive times the perdix was giving being quite a bit less than what I currently dive.

I have to say that this is the first time I have heard anyone complaining that a Suunto was more liberal! That seems to be your biggest concern so I checked. Admittedly I am running it through a Cressi not a Suunto but they both use modified versions of the RGBM so I think the comparisons are valid for a first dive NDL...

On first dives with both set for nitrox 32, the Cressi and the Petrel set at most liberal (rec mode), the Petrel gives consistently longer NDL's until about 90, then the Cressi NDL starts to exceed the Petrel. So unless your dives are greater then 90 feet, set your Perdix to low and no worries. Even at 100 the difference is only 3 minutes.

With the Cressi still set "liberal" and the Petrel on medium, the difference starts at around 60 feet. With the Petrl on High, the margin is fairly wide even at 60.
 
I have to say that this is the first time I have heard anyone complaining that a Suunto was more liberal! That seems to be your biggest concern so I checked. Admittedly I am running it through a Cressi not a Suunto but they both use modified versions of the RGBM so I think the comparisons are valid for a first dive NDL...

On first dives with both set for nitrox 32, the Cressi and the Petrel set at most liberal (rec mode), the Petrel gives consistently longer NDL's until about 90, then the Cressi NDL starts to exceed the Petrel. So unless your dives are greater then 90 feet, set your Perdix to low and no worries. Even at 100 the difference is only 3 minutes.

With the Cressi still set "liberal" and the Petrel on medium, the difference starts at around 60 feet. With the Petrl on High, the margin is fairly wide even at 60.
The difference in the two really comes out in a SECOND dive.

I was diving recently with a Perdix in tech mode (40/70) and a buddy using a Suunto. Our first dive each day was over 100 feet deep, and I was in deco before him. In tech mode being in deco with the Perdix meant I had to do a required one minute stop. By the time I got to the point it wanted me to do a 3 minute stop, we were pretty close in time. Then each day we did a second, shallower dive. On those occasions, he was in NDL trouble long before me.
 
I have to say that this is the first time I have heard anyone complaining that a Suunto was more liberal! That seems to be your biggest concern so I checked. Admittedly I am running it through a Cressi not a Suunto but they both use modified versions of the RGBM so I think the comparisons are valid for a first dive NDL...

On first dives with both set for nitrox 32, the Cressi and the Petrel set at most liberal (rec mode), the Petrel gives consistently longer NDL's until about 90, then the Cressi NDL starts to exceed the Petrel. So unless your dives are greater then 90 feet, set your Perdix to low and no worries. Even at 100 the difference is only 3 minutes.

With the Cressi still set "liberal" and the Petrel on medium, the difference starts at around 60 feet. With the Petrl on High, the margin is fairly wide even at 60.
I just got my old vyper out and confirmed you are wrong. I dont mean that in a rude way at all so please dont take offense but I did a dive plan on air on both the suunto vyper and my perdix. At 90 feet it says 22 while the perdix says 20min. The perdix is more conservative...yes only by a couple minutes...but none the less suunto is one of the most conservative computers and it surprised me the perdix even on low was still more conservative.
 
The difference in the two really comes out in a SECOND dive.

I was diving recently with a Perdix in tech mode (40/70) and a buddy using a Suunto. Our first dive each day was over 100 feet deep, and I was in deco before him. In tech mode being in deco with the Perdix meant I had to do a required one minute stop. By the time I got to the point it wanted me to do a 3 minute stop, we were pretty close in time. Then each day we did a second, shallower dive. On those occasions, he was in NDL trouble long before me.
Yeah that was my only concern would be the first dive and let's say that was your MAIN planned dive on some wreck at 100ft. You would want to make max NDL even if it meant a long surface interval.
 
and that is why i tell everyone that is interested in this sort of diving that you should get at least some sort of decompression training. a 5 minute back gas deco opens up so many more opportunities....
 
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