Shearwater's Perdix AI vs. All Comers

[KenGordon]

since you were recently asking about DIR and are considering going tech, I would strongly recommend to not get the Suunto. The reason is the proprietary RGBM algorithm. For tech diving, imho, you want a computer that runs the same algorithm as the program you use for planning your dives, and the same algorithm that your training agency recommends. That way you get consistent, predictable results. No use in planning the dive and making a deco schedule upfront, and your computer suddenly turns out to have a different opinion (underwater!). Which one will you follow

Plan the dive with DM5, the Suunto planner, and dive the plan. Sorted.

Oh, and you will find that the difference between a Suunto and 50/80 or 50/85 (what I generally dive) is not significant, at least in the normoxic range, I have not been past 60m with a Suunto.

Compare a 50/85 profile with a Helo2 P-2 plan (60m, 25 minutes, 18/45, 50% and 80%) and the run times are 80 and 81 minutes. Plans for the newer computers are similar at P0 while P-2 knocks off 10 minutes, about the same as a /95 plan.

Before you object, the exact stop times at each depth will vary. If diving in a team with different computers it will be like being on different gases, or mixed OC, CCR. If you must line up exactly and not wait for people to clear, then all use the same computer.

I used a Helo2 for a while as a backup to a Petrel on a JJ. Before that the Helo2 was the primary and a Zoop the backup. With a plan on a slate it doesn’t matter bending the Zoop.

You choose whether the computer or the slate drives the dive. The slate plan is important as it reflects the gas, but would you stay longer than the computer says just because the slate tells you to? Were you at the plan depth the whole time?

 

[ATJ]

PZ+ would probably be close to 40/85

Yeah, it is very close. I use a Perdix AI (and a Garmin) with 40/85 and set my Oceanic Atom 3.0 to PZ+ and the NDLs are almost identical.

The big difference is if I just go into deco. On a recent dive the Perdix had me do a 1 minute deco stop and the Garmin cleared deco before I got to 5m. The Atom 3.0 with PZ+ wanted 35 minutes of deco!

 

[scubadada]

Yeah, it is very close. I use a Perdix AI (and a Garmin) with 40/85 and set my Oceanic Atom 3.0 to PZ+ and the NDLs are almost identical.

The big difference is if I just go into deco. On a recent dive the Perdix had me do a 1 minute deco stop and the Garmin cleared deco before I got to 5m. The Atom 3.0 with PZ+ wanted 35 minutes of deco!

I have dived an Oceanic VT3 running DSAT with a Dive Rite Nitek Q or a Shearwater Teric for about 4 years now. I frequently do light deco, less than 15 minutes. I have never had the discrepancy you describe. At times the Buhlmann computer goes into deco 1st and dictates the stop.

 

[ATJ]

I have dived an Oceanic VT3 running DSAT with a Dive Rite Nitek Q or a Shearwater Teric for about 4 years now. I frequently do light deco, less than 15 minutes. I have never had the discrepancy you describe. At times the Buhlmann computer goes into deco 1st and dictates the stop.

All three computers pretty much went into deco at the same time.

The Shearwater and the Garmin stayed with around 1m of deco for the rest of the dive - I was clearly right on the edge of deco as far as they were concerned. (I was also diving with two 10.5L cylinders and so had plenty of gas.) While the two Buhlmann computers stayed around 1 minute of deco, the Atom kept adding minutes to the deco.

 

[Hatul]

Hi Hatul,

I was looking for a comment like yours to show me what it takes to choose g2 over perdix. The HR and the skin temperatures are with no doubt contributive to the calculation of DCLs but I am here to ask you about your experience with the Logtrak app and what exactly does it show?

Do I have the luxury to see how many calories I have burnt during the dive? What options do I have? What information are being logged?

Hi, Unfortunately the Scubapro LogTRAK sucks, so most of us are using either the free Subsurface or Diving Log 6. I went with Diving Log 6 for the PC and the iPad App DiveLog. I only use LogTRAK to view or change the computer parameters and also if I want to view the skin temp. Diving Log 6 will display the heart rate trace but not the skin temp.

The HR can be used by the computer to quantify the workload and alter the algorithm and it's displayed in real time on the computer display. I find it interesting and useful to see my heart rate when diving just as when in the gym I Ike to see my heart rate. It's also interesting to view the heart rate on the desktop computer after the dive. For example when I got close to a whale there was a sharp spike in my HR. Other than that there is no way to calculate the calories burnt during the dive.

To summarize, the G2 logs both the HR and the skin temp and these can be viewed during and after the dive.
Adam

 

[Hoag]

What are you going to dive for a backup? The Geo2, running DSAT, would be a fine match for your Perdix up to 45/95. PZ+ would probably be close to 40/85

That is what I am leaning towards.

 

[A.Hussein87]

Sorry to butt in, but I'm curious. Is it a desire of yours to burn calories during a dive or do you want that metric to see how much you happen to burn?

Hi Fastmarc,

It is a "nice to have" but definitely not my goal to burn calories during the dive.

 

[Fastmarc]

It is a "nice to have" but definitely not my goal to burn calories during the dive.

Got yah.
For me, I would be curious about seeing my heart rate. Based on how I dive and feel while diving, I would expect that it would be reasonably low. That would be a good metric to track as well IMO.