Galileo G2 too short NDL on 2° dive???

[scubadada]

Has anybody dived the G2 ZH-L 8 ADT against the 16 ADT with MB 0, PDIS off, no HR, no skin temp, and respiratory at lowest setting, i.e. as close as possible to native algorithm? Seems like an easy check on basic differences between the two

 

[Chris Karrer]

Beaverdivers + Hatul, thanks for your reply.

I have in my mind that i did one dive using EAN and the G2 was behaving normal and i don't have a heart rate sensor

I start to believe that Scubapro was tinkering with the certainly very good and tested Buhlman algorithm and that they built a NAG function to penalize the use of air and no heart rate sensor.
Scubapro Italy told me that this is how the Buhlman 16 compartment algorithm works, but i consider that as BS.
I understand that saturation/desaturation in 8 or 18 compartments is differnet, BUT not half of NDL

I will try to beorrow the G2 from my friend to verify if the NDL turns normal using EAN.

Chris

 

[Chris Karrer]

Just FYI: i was wrong regarding the use of EAN and that turn the NDL normal.
I just found a picture where my friends Galileo Terra and the infamous G2 show clearly 9 minutes difference in bottom time at EAN 31

So the culprit must be either the heartbeat sensor or a MB, PDIS or other setting.

I wrote also Scubapro USA thru their website as i have no direct email of technical service but i fear i will not get a answer ...

Chris

 

[beaverdivers]

Just FYI: i was wrong regarding the use of EAN and that turn the NDL normal.
I just found a picture where my friends Galileo Terra and the infamous G2 show clearly 9 minutes difference in bottom time at EAN 31
View attachment 445884

So the culprit must be either the heartbeat sensor or a MB, PDIS or other setting.

I wrote also Scubapro USA thru their website as i have no direct email of technical service but i fear i will not get a answer ...

Chris

Was your PDIS on or off on the G2?

 

[Hatul]

Just FYI: i was wrong regarding the use of EAN and that turn the NDL normal.
I just found a picture where my friends Galileo Terra and the infamous G2 show clearly 9 minutes difference in bottom time at EAN 31
View attachment 445884

So the culprit must be either the heartbeat sensor or a MB, PDIS or other setting.

I wrote also Scubapro USA thru their website as i have no direct email of technical service but i fear i will not get a answer ...

Chris

I may be off my rocker, but I wonder if there is a clue in your photo which shows the G2 with an unusual display color scheme that I don’t see in my G2. Is it possible that you have a different firmware or an early model of G2?

 

[tridacna]

I may be off my rocker, but I wonder if there is a clue in your photo which shows the G2 with an unusual display color scheme that I don’t see in my G2. Is it possible that you have a different firmware or an early model of G2?

Isn't that picture being taken at 100ft? I imagine the depth and camera are distorting the actual color scheme.

 

[Chris Karrer]

BeaverDivers,
The dive where the picture was taken had the settings as below:

Both computers where not used for more than 72 hours, mounted on my arm and have same settings

Galileo Terra
MB Level 0
PDIS: On
Altitude set automatic

Galileo G2
MB Level 0
PDIS: Off
Altitude set automatic

1° dive @ 30 meters/98 ft G2 has 1 minute less NDL
1.38 min surface iterval
2° dive @ 30 meters/98ft G2 has 9 minute less NDL

A higher setting in MB Level will lead to a shorter No-Stop / NDL as the manual writes:
When two G2 dive computers are used simultaneously, with one unit set to a MB level of L5 and the other to a MB level of L0, the no-stop time for the L5 unit will be shortened and more level stops will be required before the diver has the obligation of a decompression stop.

There should be no difference in NDL if PDIS is on or OFF as PDIS only change the depth and time of Deep Stops

 

[Chris Karrer]

Hatul:

Is it possible that you have a different firmware or an early model of G2?

The G2 had then the current software and as tridactna already wrote, the color of the display is distorted due the depth.

 

[CandiveOz]

Has anybody dived the G2 ZH-L 8 ADT against the 16 ADT with MB 0, PDIS off, no HR, no skin temp, and respiratory at lowest setting, i.e. as close as possible to native algorithm? Seems like an easy check on basic differences between the two

Has this issue ever been resolved or replicated? Scubadada's suggestion is logical. If the difference is due to the 8 vs 16 tissue algorithm another verification would be to upgrade the older Galileo to Trimix since it runs on 16 ADT. It would be interesting to see if that brings the two computers back in line.

 

[CandiveOz]

Has anybody dived the G2 ZH-L 8 ADT against the 16 ADT with MB 0, PDIS off, no HR, no skin temp, and respiratory at lowest setting, i.e. as close as possible to native algorithm? Seems like an easy check on basic differences between the two

I may have stumbled on the answer to Scubadada’s query/request. I was reviewing the Scubalab 2016 and 2017 computer dive test results from a posting made by @Jay_Antipodean. Scubalab used the same dive profiles to test the computers in both years. Jay had averaged the NDL results ranking them from Liberal to Conservative (ie longer average NDL to shorter average NDL).
Place of dive tables in modern diving
I noticed a pattern between the two Scubapro computers tested in 2016 versus the two tested in 2017. Generally the 2016 computers display a longer NDL, specifically on Dives 2 and 4. I then check the manuals of each computer. The 2016 computers; Mantis 2 and Aladin Tech 3H both ran the ZH L8 ADT MB PMG algorithm while the 2017 computers; G2 and Aladin Sport (matrix) ran ZH L16 ADT MB PMG.

To my understanding Subalab ran the tests with the computers’ default setting without human biometric input on the Mantis 2 or G2. Because these were chamber dives, with just the computers themselves and not actual scuba dives, they didn’t use the heart rate monitor to measure heart rate and skin temperature or the tank transmitter to measure breathing rate. Also, according to the user manuals, the default setting for microbubble level is L0 and PDIS default is off. So I think these tests meet Scubadada’s criteria; MB 0, PDIS off, no HR, no skin temp, and respiratory.

So basically the difference between the two sets of computers should only be due to their algorithms. And in conclusion, based on Scubalab's chamber dives, the 16 tissue model does result in a shorter NDL than the 8 tissue model for a repetitive dive. I have included a summary table of the results: