Actual Experience with Shearwater AI

[ickebins]

I agree with what you write, Oldbear but regardless of that I want to know what the percentage of offset is. The same like I do with my car and the tank. Knowing what the equivalent of red to E is provides ME a safer feeling knowing if red till E is 10, 20 or 50 miles.

 

[wetb4igetinthewater]

My understanding is that SPG's are accurate in the mid range, not at the low or high (anyone correct me if I'm wrong).

I just gave my Perdix AI a spin Thursday night. Worked like a champ. I'm really happy with it, and I know I won't have battery life issues (my only complaint with my Aeris CS A300).

 

[Joneill]

What about cross-posting and letting Shearwater know about this thread? Perhaps they are in a position to shed some light....

As I'm also a Perdix AI user an answer would be great.

I did reach out to Shearwater and this was their feedback:

"The AI transducers are governed by the same standard as analog gauges (EN250), which specifies 15 bar accuracy at 300bar (about 225psi at 4500psi). It would not surprise me for an analog gauge to read 150psi off at 3000psi – I have certainly seen some with that size of error.

We have tested the transducers used in the AI transmitters, and found them typically 2% accuracy or better, or 60psi at 3000psi.

Note that for both the analog gauge and the AI transmitter, even if they were out 200psi or more at 3000psi, the error typically scales with pressure – that is, as the pressure gets lower the error gets smaller. For example, if your gauge is 150psi lower at 3000psi it is probably only 15psi lower at 300psi. Any errors at low pressure (‘zero offset’ - such as the analog gauge reading 200psi with no pressure) are more serious. I have tested many AI units, and never found one with more than about 5psi of zero offset – they are very good in this respect. This is an easy test for you to perform as well – just release the regulator pressure fully and remove the first stage from the tank to ensure no trapped pressure in the first stage – the AI should read very near zero. Note that the AI units use < 50psi as a power-save turn off threshold (after 2 minutes)."

I have not had time for adfitional follow-up on this.

 

[lowflyer]

I found it impossible to make a Bluetooth connection between the Perdix AI and Shearwater Desktop. Then I stumbled upon the "Release Notes" and discovered that, unlike the Perdix, the Perdix AI requires your computer to have Windows 8 or above to access Shearwater Desktop. Fortunately I have a lap top with Windows 10 and was able to make it work.

 

[ickebins]

It's also stated at their download page for Desktop.

Windows Requirements

• Microsoft Windows Vista, Windows 7, Windows 8 or Windows 10
• Perdix AI requires Bluetooth LE. This is only available on Windows 8 or later
• Bluetooth radio if Shearwater Desktop is being used with a Predator, Petrel 1 & 2, NERD, or Perdix. Perdix AI requires a CSR 4.0 Bluetooth radio
• IrDA adapter if Shearwater Desktop is being used with a Pursuit

Mac Requirements

• Mac OS Sierra installer issues: Shearwater Desktop certificate issue
• Perdix AI requires Bluetooth LE. This is only supported on Mac OS X 10.10.0 or later
• Intel Core Duo or faster processor
• Mac OS X 10.4.9 or later

 

[stuartv]

And...

Perdix AI not supported on Windows 7

 

[James R]

The Perdix AI that I bought my short, blonde, dive buddy for valentines is about 150 lower at 3000 and dead on at 500 with my Oxycheq and Dive Rite brass and glass SPG, which seems to validate what was posted above. All in all I am not worried about it -- if it shows 500psi she's already at the surface anyway and I have been out of air for a while

 

[Alastor]

Just to to calm those worried about AI wrong reading, my perdix AI arrived two days ago and yesterday I connected it to an oceanic wireless transmitter.
Then I compared it with a good SPG I know is quite accurate. Then I also connected other 2 suunto transmitter leaving the accurate mechanical SPG attached and repeated the test.
This is the result:
SPG 200, 150, 100, 50 25
Perdix + Oceanic 199, 147, 99, 49. 23
HeLO2 + suunto1 199, 152, 101, 51, 25
D4i + suunto2 198, 149, 99, 47, 25

So they are more o less within few bar from the SPG and, probably they could be more or less the same - is difficult to estimate 1 or 2 bar from an SPG dial.

Anyway, I'm happy with that.

 

[Neilwood]

Just back from a weekend away with my new Perdix AI - wow what a difference to diving with the Cressi. Vis was pretty poor (about 3-4m at best) but could read the screen no problem. No issues with AI connection at all and all my checks with SPG were within a few bar of the reading on the screen.

To sum it up - so glad I bought it.

 

[kelemvor]

So you do care... thanks

Wow that guy's pretty good. Except that garbage about holding the fort. Why would someone want to hold a fort, and how would you fit it into your grip in the first place? You hold down a fort, by standing inside of it. Oh well, I've got a new youtube subscription... Thanks!