Question Shearwater Perdix AI

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TravelGas

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Does anyone know anything about the optional Shearwater computer Deco algorithms that can be purchased,

VPM
or
DCIEM

What is the advantage to having that with respect to Tech diving ? What do they do for you compared to the standard algorithm ?
Thanks.
 

tursiops

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They offer you nothing worth paying for, for Tech or Rec.
VPM is not popular these days, for various reasons.
DCIEM is probably only offered since it is the Canadian government standard, and Shearwater is a Canadian company.
 

Wibble

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Don't bother.

Use Buhlmann + Gradient Factors like everybody else. Life's much easier.
 

loosenit2

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lets not be so hasty as to say they offer nothing worth paying for. Varying Permeability Model (VPM) is a bubble model for making decompression calculations; as opposed to a Haldanian model. Bubble models are out of fashion right now, but there are still some adherents. In fact a number of computer manufacturers still use versions of bubble models, for example Aqua Lung and Suunto both use variations of bubble models. There are also a few tech agencies that advocate the use of bubble models (i.e. GUE).

In practice if you prefer bubble models you can use gradient factors in a standard Buhrmann model to very closely resemble what a bubble model would tell you to do.

All that said most of the latest science is pointing away from Bubble Models as the most effective and efficient decompression algorithms, but that is still a matter of heated debate.
 

Wibble

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We don't need another bubble vs Haldanian model discussion/row!

The practical issues with the bubble models is it doesn't result in the same decompression curve as the Buhlmann (ZHL-16 GF) algorithm. There's several bubble models too; Suunto have at least two, neither compatible with others.

I used to dive with a Perdix and a Suunto backup. Even on the most aggressive setting, the Suunto would always add time in the water when the Perdix, running Buhlmann 50:80, had cleared.

Again; for practical reasons use the pretty much standard Buhlmann algorithm -- it just works and is compatible across a wide range of computers.
 

loosenit2

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Not trying to start a debate, I fall clearly into the Buhlmann GF camp; But the OP asked a question, better to offer resources to help him understand than just simply say do this, don't do that, with no explanation. Educate NOT dictate.
 

scubadada

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...In fact a number of computer manufacturers still use versions of bubble models, for example Aqua Lung and Suunto both use variations of bubble models...
Most Aqua Lung computers run PZ+, a proprietary version of Buhlmann, written by Pelagic Pressure Systems. The i330R runs Buhlmann ZH-L16C Sport Version. It has 3 presets of 90/90. 35/85, and 35/70.

Suunto computers run several versions of RGBM; Suunto RGBM, Technical RGBM, Fused RGBM and Fused RGBM 2. The Eon Steel Black has the option to run Buhlmann with GF in addition to Fused RGBM 2

Mares computers run a version of RGBM, the Genius runs Buhlmann and GFs with a somewhat limited range

Cressi computers run a version of RGBM.

Atomic runs/ran a version of RGBM

For reasons that are quite clear to many of us, MultiDeco runs Buhlmann and VPM
 
OP
TravelGas

TravelGas

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Copy, Bühlmann for the win.

Now if somebody would just quietly drop me a PM and put me onto a Shearwater dealer who would give me a break on a Perdix AI and a Swift Transmitter, I would be thankful.
 

tursiops

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Now if somebody would just quietly drop me a PM and put me onto a Shearwater dealer who would give me a break on a Perdix AI and a Swift Transmitter, I would be thankful.
Yeah, good luck with that.
Save some money; get the old transmitter, and a used Perdix.
 

Marie13

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Now if somebody would just quietly drop me a PM and put me onto a Shearwater dealer who would give me a break on a Perdix AI and a Swift Transmitter, I would be thankful.

Haha. Good luck with that. Probably won’t happen. Everyone prices Shearwater the same.
 
https://www.shearwater.com/products/perdix-ai/

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