Shearwater Perdix AI

[kelemvor]

I think they still manufacture and sell petrel 2, don't they?

If you take the Anti AI sentiment on SB, I'm sure they'll be a ton of buyers who want a Perdix without that pesky AI cluttering up the computer.

I think shearwater still makes and sells petrel 2. Besides, most of the people who don't already own a shearwater DC probably weren't going to buy one in the first place.

Time will tell if expanding their offerings to recreational diving affects them negatively. I have my doubts, since the addition of the recreational UI didn't cause a mass exodus. They even added that non technical feature to all their dive computers.

 

[stuartv]

If you take the Anti AI sentiment on SB...

Yeah.... We'll see how long that lasts. Somehow, I don't see all the Shearwater Fan Boys posting anything, NOW, that says a Perdix AI is a piece of junk full of useless crap, that nobody should buy unless they want to die.

But, I DO think that the Shearwater warranty means that any smart shopper should be looking at used, if they want a non-AI Perdix. So, sales of new non-AI Perdix are probably going to be totally flat for a while.

And anybody who really wants to buy new should really consider spending the extra $65 for the AI version, just for the better resale value, even if they don't PLAN to use the AI themselves.

You know, because when the Shearwater wristwatch tech computer (with AI) comes out next year, anyone who buys a new non-AI Perdix now is REALLY going to be pissed about their resale value.

 

[stuartv]

I think they still manufacture and sell petrel 2, don't they?

I think shearwater still makes and sells petrel 2. Besides, most of the people who don't already own a shearwater DC probably weren't going to buy one in the first place.

Time will tell if expanding their offerings to recreational diving affects them negatively. I have my doubts, since the addition of the recreational UI didn't cause a mass exodus. They even added that non technical feature to all their dive computers.

I agree with the last part.

I disagree about most people who don't have a SW weren't going to buy one in the first place. Well, sort of. Obviously, among all owners of recreational computers, it is true that most (the vast majority) were not going to buy a SW DC, no matter what. But, I think we'll see that there are a lot of people who didn't buy one before because either they didn't want a brick like the Petrel, or they wanted AI. I suspect the Perdix AI is going to be SW's biggest ever seller, by far. I had a Petrel 2. I sold it because I didn't like the brick on my arm AND I wanted AI. The PAI is now on my Christmas List - possibly only getting bumped if Ratio announces that their new AI capability will work with PPS transmitters (which I reckon is pretty unlikely).

There are 3 reasons why they still sell the P2:

- People who want a Fischer connector (which wouldn't fit on a Perdix).

- Government contracts for ongoing sales of the P2. Contracts that would have to be changed in order for the same agencies to switch to buying Perdixes.

- People who want the extra depth rating of the P2. For when 850ft is not deep enough (but 980 is). LOL

I imagine all those government POs will get updated eventually to allow purchase of Perdixes and then the non-Fischer Petrel will fade into the sunset. P2 EXT will hang around for CCR divers (and anyone who needs to go deeper than 850' - who are probably using a CCR anyway).

 

[scubadada]

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.

 

[scubadada]

I'm impressed with Shearwater customer service. I have had 2 queries answered within hours, despite the fact that they must be overwhelmingly busy at DEMA

 

[stuartv]

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.

Interesting! Thanks for sharing that.

So, it does not work just like the Oceanics. With my Oceanic and Hollis computers, the transmitter is specifically associated to a gas. So, the displayed tank pressure is the pressure of the currently selected gas. And if you do a gas switch, and the new gas has a transmitter associated, then the displayed pressure would be the gas you switched to, automatically.

The way SW has done it means that if you do a gas switch to a second cylinder with a transmitter, you have to do the gas switch on the computer AND switch which cylinder is being displayed as the tank pressure. Otherwise, you'll be breathing from one cylinder and seeing the tank pressure of a different cylinder.

This seems especially annoying if you're diving sidemount and using transmitters on each of your main tanks. I suppose, to work well, you would have to configure the display to show both tank pressures at the same time. But that means you've now given up 2 of the 3 customizable display slots to tank pressure. It sure seems like it would be nicer and simpler to just have one tank pressure on the display and have it automatically be whichever one you've indicated you are breathing from.

I, personally, am totally fine with the decision to not display a GTR once you've gone into deco. But, I do think it would be better if they always displayed GTR, it was based solely on the gas you're breathing, and it included at least all mandatory stops and, really, any safety stop that the computer is going to call for. For people who are doing very simple deco dives on back gas only, this would possibly be useful, and I don't see any reason to NOT do it. It shouldn't give anyone an excuse to stay down longer than their plan, but it might give someone info that would sway them to turn their dive earlier than planned because they didn't realize they were using more gas than what they allowed for in their plan.

I mean, if the rules were:

- GTR only reflects the selected breathing gas
- tells you when to start your ascent, following ALL stops the computer tells you, in order to surface with the configured reserve

Well, how could it be any simpler?

 

[scubadada]

Interesting! Thanks for sharing that.

So, it does not work just like the Oceanics. With my Oceanic and Hollis computers, the transmitter is specifically associated to a gas. So, the displayed tank pressure is the pressure of the currently selected gas. And if you do a gas switch, and the new gas has a transmitter associated, then the displayed pressure would be the gas you switched to, automatically.

The way SW has done it means that if you do a gas switch to a second cylinder with a transmitter, you have to do the gas switch on the computer AND switch which cylinder is being displayed as the tank pressure. Otherwise, you'll be breathing from one cylinder and seeing the tank pressure of a different cylinder.

This seems especially annoying if you're diving sidemount and using transmitters on each of your main tanks. I suppose, to work well, you would have to configure the display to show both tank pressures at the same time. But that means you've now given up 2 of the 3 customizable display slots to tank pressure. It sure seems like it would be nicer and simpler to just have one tank pressure on the display and have it automatically be whichever one you've indicated you are breathing from.

I, personally, am totally fine with the decision to not display a GTR once you've gone into deco. But, I do think it would be better if they always displayed GTR, it was based solely on the gas you're breathing, and it included at least all mandatory stops and, really, any safety stop that the computer is going to call for. For people who are doing very simple deco dives on back gas only, this would possibly be useful, and I don't see any reason to NOT do it. It shouldn't give anyone an excuse to stay down longer than their plan, but it might give someone info that would sway them to turn their dive earlier than planned because they didn't realize they were using more gas than what they allowed for in their plan.

I mean, if the rules were:

- GTR only reflects the selected breathing gas
- tells you when to start your ascent, following ALL stops the computer tells you, in order to surface with the configured reserve

Well, how could it be any simpler?

I agree with you entirely, I really like my Oceanic ATR!

 

[CuzzA]

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.

Craig,

I personally never use the GTR feature of my AI computer. I do however utilize the mid and reserve tank pressure warnings. And I don't think I use them like most people do.

For example, I enter my mid pressure warning as my turn pressure. Tank pressure minus reserve divided by two = mid pressure warning. I do not set my reserve warning as my reserve, but rather my ascent pressure warning.

Aside from the convenience of heads up tank pressure display, I find the warnings are an excellent safety measure for task heavy diving. I normally am anticipating the warning, especially my ascent pressure warning as it's typically right about the time my tank shifts in trim due to buoyancy changes, but it's a nice reminder that says, "Hey buddy, stop what you're doing, don't chase that fish and head up!"

 

[stuartv]

I mean, if the rules were:

- GTR only reflects the selected breathing gas
- tells you when to start your ascent, following ALL stops the computer tells you, in order to surface with the configured reserve

Well, how could it be any simpler?

This doesn't really work for sidemount. How about if the rules were:

- GTR is based on the current breathing gas and any other transmitters that are registered with the computer and are configured with the same gas mixture. It assumes all tank sizes are the same as the current breathing gas. Meaning, it assumes if you're consuming 100 psi/min on the current tank, it assumes you'll consume 100 psi/min on any other tank with the same gas. Alternative, it would only include tanks in the calculation that you have used during the dive and that have the same mix. So, to start, it would only reflect one of your sidemount tanks. But, as soon as you did your first gas switch from one side to the other, it would get a consumption rate reading on the second tank and then start including both tanks in the GTR.

- tells you when to start your ascent, following ALL stops the computer tells you, in order to surface with the configured reserve

 

[CuzzA]

I should also add that while I'm tempted to remove my SPG, I haven't done it and at this point I don't think I will, as the two warnings are a great time to cross check with my SPG to make sure both are in agreement.