Shearwater Perdix AI

[Oldbear]

So, If I buy a Perdix AI, and already have a VT3, both on the same transmitter, do I still need to have my SPG?


Doesn't really matter, I've had the SPG for six years, I would probably miss it.

With only one transmitter it really doesn't matter how many receivers you have...I would still carry a SPG for redundancy.

 

[Pullmyfinger]

I almost bought a new Perdix the day before the announcement of the AI...

you chose wisely - Google 検索

 

[Compressor]

I almost bought a new Perdix the day before the announcement of the AI...

Very lucky. Good for you.
Tech moves fast. Sometimes one gets lucky, sometimes one doesn't. I still love my Perdix nonAI.

 

[Hatul]

I received a very prompt and detailed response from Shearwater regarding GTR function of the Perdix AI. The ascent is taken into consideration. I have 14 years and 1200 dives experience with the Oceanic ATR. The Oceanic ATR is quite accurate, retrospectively, I'm not sure it takes into account the SS. I often surface with a little below the entered end pressure. The comments regarding deco are appreciated. I am reasonably confident that the Perdix AI GTR will work out well, as planned, and appropriately.

Hi Craig,
I spoke with our engineering team about this and their response is below:

Yes, ascent is considered, but not safety or deco stops.

Our GTR does include the ascent to the surface (at 33 ft/min or 10m/min), but does not include safety stops or deco stops. The gas needed for safety stops is typically small (<200 PSI) and easily budgeted with an appropriate reserve pressure. We didn’t remove the safety stop gas usage from GTR, because we felt it was odd having a GTR of 0 when at the safety stop and still with pressure slightly above the reserve pressure.

Regarding deco, we do not feel that GTR type predictions are a good tool for decompression diving. There are too many complexities when decompression diving, which typically involves multi-tank diving. Once multiple tanks are introduced, there are suddenly many variables due to different styles of diving and gas planning. The complexity of properly setting up AI for accurate multi-tank diving overwhelms its utility. Originally we designed the firmware to support more tanks and multi-tank GTR. However, during our testing, the testers (Shearwater engineers who know the product very well) frequently made setup mistakes when using multiple tanks that resulted in inaccurate GTR. For this reason, when deco is needed, GTR is not shown (since we feel GTR is a tool for no-stop diving).

First and foremost, the greatest advantage of wireless AI is having pressure displayed on the wrist on a nice bright color display. Advanced features like GTR and SAC are nice, but the complexity of handling them with multi-tank diving defeats their utility. We do not associate a transmitter to any specific gas in the gas list. There are simply 2 transmitters that can display the pressure. Optionally, 1 of the transmitters can be selected for SAC and GTR calculations.

The Perdix AI firmware is new, so we are listening to customers to optimize the feature set. Adding support for more transmitters is possible, or more complex GTR calculations. We aren’t promising any changes, but are definitely listening. Any changes we do make will need to align with our philosophy of simplicity and usability.

We appreciate your questions and feedback as this helps us design better products.

Let me know if you have any other questions .

Cheers,

Alex Tayler

Marketing Coordinator
Shearwater Research Inc.

Thank you for explaining the definition of GTR. I agree with Stuart that there is no reason not to account for deco obligation and safety stop. It appears to be a lazy implementation of GTR. My old Galileo accounts for the stops as well as for a variable ascent rate. Perhaps Shearwater can learn from Uwatec on the implementation of GTR.

 

[CarcharodonCarcharias]

Tyler,

Great to see your participation here. If I could make a suggestion, and I think this goes for all manufactures producing transmitters, perhaps a different color than black would be a good idea to avoid accidentally lifting a tank by the transmitter. They look so much like tank valve knobs.

I'd suggest red, but perhaps Shearwater Blue for SW customers.

Add a 6" hose and your problem is solved. LOL

 

[CarcharodonCarcharias]

So, If I buy a Perdix AI, and already have a VT3, both on the same transmitter, do I still need to have my SPG?


Doesn't really matter, I've had the SPG for six years, I would probably miss it.

As much as I love my AI, I would not dive w/o a SPG as a backup. Worst comes to worse, use the SPG as a self defense tool or smack the unscrupulous diver that is carving his/her name onto the live coral.

 

[CarcharodonCarcharias]

I almost bought a new Perdix the day before the announcement of the AI...

Good man. Looks like lady luck is on your side.

 

[charlier]

Thank you for explaining the definition of GTR. I agree with Stuart that there is no reason not to account for deco obligation and safety stop. It appears to be a lazy implementation of GTR. My old Galileo accounts for the stops as well as for a variable ascent rate. Perhaps Shearwater can learn from Uwatec on the implementation of GTR.

Its seems a bit unfair to suggest that SW used an lazy implementation of GTR. You might have a fair point suggesting that SW include OC single tank deco obligation as part of GTR. With multiple-tanks and mixed gases, I would not use a calulated GTR. What are you thoughts here?

 

[WarrenZ]

Idea New gauge readout: does the math for you Gas time remaining - Time to Surface = TTD readout (Time Till Drowning).

 

[guyharrisonphoto]

From the perspective of a single tank rec diver (and owner of a Galileo), I too believe that GTR for a single tank should be based on TTS and not just ascent. This is not only handy but could be an important safety back-up as well, If I, for some unexpected reason, go into deco, I would like to have GTR account for the stops instead of having to calculate on the fly, at depth, how the extra 3 or 5 or minutes on the TTS affects the GTR. The Uwatec algorithm does this (and even as Hatul said accounts for a variable ascent rate 60'/min up to 60' then 30/min and even a little slower above 20). So does the Oceanic, from the comments from the people using that.

So, this is one step beyond the first step that Shearwater could consider, as it has been done, for years and reliably, by at least two of the biggest computer makers out there.

This is a helpful suggestion and not a criticism. I for one am thrilled by the new AI perdix, especially since Shearwater listens and does firmware upgrades when it sees fit.

For those who are disappointed because they bought the nonAI, why? I did not buy a Perdix because it did not offer AI. I was not willing to make the trade for the great display/algorighm/quality and not get the AI. So, I kept my Galileo. For those who bought, they were willing to make this trade-off and should have no complaints and no reason to ask for an upgrade or trade-in. No one is forced to buy a computer, after all.

When my Galileo bites the dust (if it ever does, its been pretty bulletproof), I know where my $$ are going.