Scubapro Galileo G2 short NDL

[Chris Karrer]

I repost this tread from the Scubapro Manufacturer forum here as i don't get a lot of help there.

Basically the promblem is this:
I bought a Scuabpro Galileo G2 for a friend and was testing it against my Suunto Eon Steel.
Doing several 100 ft dives on our wreck here is discovered that:
The Galileo G2 gives me every time on the second dive 7 minutes less NDL than my Suunto Eon Steel having the same settings.
Well, i finally made it to check the Galileo G2 together with a Galileo Terra from my buddy.
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

I'm still wondering where this difference is coming from???

Chris

The dive from yesterday in the picture below was breathing EAN31 but the same happen using air

 

[BoltSnap]

Unrelated question but where and when did you get the "terra"? I don't remember seeing it in the SP website anywhere.

 

[Chris Karrer]

Unrelated question but where and when did you get the "terra"? I don't remember seeing it in the SP website anywhere.

It's the computer of my buddy here in Italy.
In this time (aprox in 2008) there where 3 models of the Galileo, the Terra, the Luna and the Sol, all 3 common computers in Italy.
Chris

 

[jchance]

You will get little out of Scubapro unless you got either to their website OR a dealer. They think in reality that the store and not you are their customer. The only thing that could be causing the differences is a change in the algorithm.

 

[Chris Karrer]

The only thing that could be causing the differences is a change in the algorithm.
You are very right I wrote a a email to the dealer and he asked Scubapro I got a email from Scubapro saying:
That the Galileo Luna uses ZHL8 with 8 tissues and the G2 uses ZHL16 with 1 tissues and this can lead to different calculations,
and that this is the cause and that this behavior is not anomal for the G2.

I am a overweight, non sporty and 53 year old dive guide and instructor and make about 400 dives per year and dive for weeks 7 days a weeo 2-4 dives per day.
I made more than 3500 dives wth Suunto Eon, Vyper, Cobra, D6i , DX and now a Eon Steel, about 30% of them between 90 and 140ft and
i never ever had any issues with not even light DCS symptoms.
My personal experience let me believe that the Suunto algorithms do their job fine and i am very surprised about the short NDL of the G2 on repetitive deeper dives.

Chris

 

[scubadada]

Hi @Chris Karrer

It may be possible that the G2 and the Terra are not running exactly the same decompression algorithm. The Galileo series runs Buhlmann ZH-L8 ADT while the G2 runs Buhlmann ZH-L16 ADT. I have not heard that anyone has noticed differences of the magnitude you describe. Other than changing the number of tissue compartments, I've not heard a description of the new algorithm.

I assume you are not diving the G2 with the HR and skin temperature strap, that could affect NDLs. Lastly, perhaps the breathing rate monitor on the G2 is having an effect. It appears it can be adjusted as 12 steps above or below the default setting.

Let us know if you figure this out

Edit: Sorry Chris, you were replying while I was typing and had already thought of the algorithm explanation, which might be it

 

[Chris Karrer]

Thanks ScubaDada!
Your explenation is basically the same what the Italian Scubapro technician wrote and this may be true (or just a excuse to not investigate more from the SP technician side)
In any case, it is my experience and believe that 7-9 minutes less NDL on a second dive at 100ft is a odd behaviour and exagerated.
You may be right that breathing rate, skin temp and heart beat rate may influence the NDL,
Lowering NDL because i don't use the additional cost pressure sensor to transmit breathing rate and the extra cost skin temp and heart beat sensor reminds me to
a Nag Screen in some shareware software.
No additional (expensive) optionals for the computer will lead to less bottom time ...

Well, it would be a interesting test to repeat the dives, once with transmitter and temp/hart beat sensor and then without to verify this hypothetis.

Chris

 

[BoltSnap]

The Galileo G2 gives me every time on the second dive 7 minutes less NDL than my Suunto Eon Steel having the same settings.

This is very interesting, I didn't think that it was possible to be more conservative than the Suunto computers

 

[scubadada]

Hi @Chris Karrer

As you don't use the HR/skin temp strap or the gas pressure transmitter, Scubapro's human factors would not be negatively impacting NDLs. The only obvious variable left is the decompression algorithm.

I would think there are others who have dived one of the Galileos along with a newer G2. It would be interesting to hear from them. Maybe @Hatul has experience with both

 

[scubadada]

This is very interesting, I didn't think that it was possible to be more conservative than the Suunto computers

I used to think this too, and it may be generally true. @Diving Dubai provided me with additional information some time ago. At least for the Eon Steel and the Fused RGBM algorithm, if you set the personal adjustment value at P-2, the computer appears to be as liberal as DSAT. I don't know if this would continue to hold up for repetitive dives.