When is ZH-L16C GF not ZH-L16C GF? When it is a G2 Tek computer

[scubadada]

Was this announced on their official website or just offerings by their dealers in US?

I did not see this announced by Scubapro. I noticed the sale prices on scuba.com and then saw the same sale prices at Divers Supply. Scubapro does not seem to be discounted unless approved by the manufacturer. Some of these sale prices are quite significant, 26-43% lower.

 

[BoltSnap]

I did not see this announced by Scubapro. I noticed the sale prices on scuba.com and then saw the same sale prices at Divers Supply. Scubapro does not seem to be discounted unless approved by the manufacturer. Some of these sale prices are quite significant, 26-43% lower.

Yes, no official announcement from SP yet prices are hugely discounted at an unprecedented scale.

 

[lexvil]

I’ve seen these deep discounts from several retailers, I’m hoping this is SP wanting to be more market competitive and not an aqualung type sell off.

 

[lexvil]

G3 with GF should be just like G2 Tek. If you switch to ZH-L16 ADT MB PMG the HUD has MB Level 0 to 5 and the G3 has MB Level 0 to 9 so hard to make a match there. Maybe a GF High 5 more than the HUD will get you close.

The big difference is that the HUD does not use Altitude Classes. So at sea level the G3 will be a bit more conservative than the HUD at equivalent settings.


View attachment 836201

I’m running GF 40/80 on the HUD and MB 0 on the G2, my diving doesn’t normally get anywhere near NDL very often at least not locally. I find the HUD incredibly nice for navigation.

 

[lexvil]

Ok ,bit the bullet and have one on the way, my dilemma was with getting the newer smaller transmitter which comes at a very nice package price but with two of the older “smart” ones on hand I decided to wait on that and just get the G3.

 

[bardass]

I have learned a little bit more about the G2 Tek algorithm. I am sure it changes no opinions on who will or will not use it, but I do like to understand how the computer algorithm works and share that information.

Deco schedule does not match Shearwater or Scubapro HUD
While the G2 Tek is more conservative than the Shearwater, it is not because they have implemented an incorrect or wrong ZH-L16C + GF algorithm. It is the inputs they chose to use for the algorithm that cause the differences.

I know this is not a great analogy, but the Pythagorean theorem is a2 + b2 = c2. If I use a = 1.1 and b = 2 while another person uses a=1 and b=2, it is not that the equation is wrong, it is that the inputs to the equation were different. I believe this is what is happening with the ZH-L16 algorithm used by Scubapro. Scubapro does document this in the user manual. It is in the Altimeter section of the user manual. I have copied the text from the section below, and made the important text bold.

"Barometric pressure is variable, changing with weather and atmospheric pressure at any particular elevation. Dive algorithms use altitude classes which are directly derived from barometric pressure. Displayed altitude is determined based on the current barometric pressure and is therefore a relative value. "

Scubapro uses altitude classes as the input into the decompression algorithm. They use the top end of the altitude class. So if the Altimeter is measuring pressure at Sea Level, you are in altitude class C0 and the input into the algorithm is 1,000 meters. Playing around in Multideco and changing the Dive Elevation depth between 0 and 1,000 meters does seem to give run times with a difference similar to what I saw when I performed an actual test dive with the Shearwater and G2 Tek.

View attachment 831577

Dive Planner shows shorter NDL times.
There is a double hit here. The dive planner is using the current altitude class (1,000 meters at sea level) and the G2 Tek dive planner assumes the dive starts at the depth indicated. The G2 Tek dive planner does not calculate a descent rate like the Shearwater and Garmin computers do.

Scubapro HUD is different than the G2 Tek
This has been confirmed. Scubapro HUD does not use altitude classed and uses the measured barometric pressure.


An interesting note...
For anybody that liked the SEABEAR computers (Scubapro bought the company in 2015), the founder, Dr. Arne Sieber stayed with Scubapro as the R&D Manager for Scubapro Dive Computers until 2017. Dr. Sieber founded Oxygen Scientific, which has solid state O2 sensors and dive computers with wireless PO2 and Air integration. Halcyon will sell them in their Symbios CCR ecosystem.

descent rate infinite : confirmed
upper end of that altitude class : confirmed