Scubapro G2 Algorithm?

[guyharrisonphoto]

I posted this in the Scubapro manufacturer forum and have not received a response. Since these are at dealers and are in the hands of owners I am posting it here as well.

I have a Sol with the ZHL-8 that is standard on the Sol/Luna. I had been considering the trimix upgrade which was based on ZHL-16 but was told by several people, including my dive shop (a platinum dealer), that the upgrade made the computer much more conservative for repetitive recreational diving, which I mainly do. I have been very happy with the regular algorithm, so I did not upgrade.

Now, we have the G2, which seems to be a great upgrade. But, it is advertised as running a ZHL-16 type algorithm, and does trimix.

My question is, is this new "standard" algorithm the same one as the "trimix upgrade" on the Sol?

Can a dealer (beaverdivers?) or an owner (I assume some owners still have their Sol or Luna) give a comparison of how the G2 compares with the Sol/Luna on repetitive recreational dives? Is it more conservative? About the same? Has it been "in the wild" long enough for anyone to tell.

How do the dive planners on each compare when planning a single dive, to at least get a feel for any difference between basic NDLs.

 

[mnjhuz76]

I have a Sol with the ZHL-8 that is standard on the Sol/Luna. I had been considering the trimix upgrade which was based on ZHL-16 but was told by several people, including my dive shop (a platinum dealer), that the upgrade made the computer much more conservative for repetitive recreational diving, which I mainly do.

Sorry, no answer to your question, but it made me think of something:
Isn't deliberately going for an algorithm with less tissue compartments just because it gives you better NDLs and shorter deco times kind of an ostrich approach?

My thoughts are, that just because the computer doesn't take the additional compartments into account, they don't simply disappear, correct?

Or is this all about marketing - the more tissues, the better it sells?

Cheers,
Peter

 

[guyharrisonphoto]

Remember, I am recreational diving, so I am not going to get into an abstract discussion of which algorithm might be safer in a technical diving context.

In general, algorithms are a mathematical model of decompression. There are not 16 versus 8 "real" compartments in your body, so nothing "exists" or does not "exist" in that respect. It is a mathmetical estimate of how certain tissues react, nothing more.

Simple fact, the ZHL-8 is in use for decades on many thousands of scubapro computers, for probably hundreds of thousands and perhaps millions of dives and is a proven safe algorithm (as is DSAT, the Suunto, the ZHL-16 and several others in use on different brands of computers), with "safe" meaning that the risk of DCS is within acceptable percentage of occurrence.

For recreational diving, there is no proof that any commonly used computer algorithm in use is "safer" than any other in terms of DCS.

Because the ZHL-8 basic algorithm is safe, and, for me, very workable in NDL's over repetitive dives, I do NOT want Scubapro to switch to a more conservative base algorithm just for the sake of "16" versus "8".

 

[blac86]

This is like complaining about crumple zones and seat belts in cars.

The galileo/luna was simply a poor technical computer and not up to the standards of shearwater/ratio. The zhl-8 has its flaws and there's a reason it's been moved away from.

 

[dmaziuk]

Sorry, no answer to your question, but it made me think of something:
Isn't deliberately going for an algorithm with less tissue compartments just because it gives you better NDLs and shorter deco times kind of an ostrich approach?

My thoughts are, that just because the computer doesn't take the additional compartments into account, they don't simply disappear, correct?

Or is this all about marketing - the more tissues, the better it sells?

Computers make very fast very accurate misteaks. With twice the compartments the mistakes are twice as accurate. In serious terms, you're looking at twice as accurate approximation of something that is largely educated guesswork based on some dead goats and century old caisson workers.

Nor does it follow that fewer compartments give you "better" NDL, whatever that means. E.g. if your sat/desat curve is a straight line, you only need one compartment. If 8 track the actual tissues "close enough", going to 16 only means you need double the CPU power etc. to get "closer than enough". (And I'm not commenting in the "if" one way or the other.)

 

[Nebulas Void]

It would be good to have an actual empirical data driven understanding of how the ZHL8 Vs ZHL16 functions. This can of course only be explained by Uwatec who have modified the algorithms for their respective devices unto creating their proprietary "human factor diving" modes . In the case of the inquiry as to which will better serve the average recreational diver I think it would be much like using your PADI tables Vs SSI or any other mathematical dive tables. The minute differences for the masses of recreational divers is like the preference between peas and corn for your evening meal.

 

[Hatul]

I did around a week of diving in Cozumel a few months ago with my G2 as the primary computer and Aladin Tec3G as a backup and reported my comparison in another thread, which I’ll quote here. They were all rec level dives with no deco stops:

I’m on my way back from Cozumel and did several dives with my G2 and Aladin Tec G3 as a backup, so I had a chance to compare the two. The Aladin uses the 8 compartment model of the Galileos and the G2 the newer 16 compartment model. I dove both with MB set to 2, and the G2 had PDIS turned on while the Aladin PDIS I set to off.

The two computers tracked very close, the Aladin slightly more liberal but not significant. Recall that the G2 has 9 MB levels while the Aladin has 5. When I had level stops they were identical except that the G2 showed a longer Total Ascent Time, because in the G2 they slowed the ascent rate.

Overal I found nothing worrying about the readings of the G2 and was similar to the Aladin which uses the algorithm of the older Galileos.