Do you really understand your computer, or is it a threat to you?

[Centrals]

Bells and whistles have no contribution to safety.

"This computer is capable of calculating deco stop requirements. These calculations are at BEST a GUESS of the real physiological decompression requirements!
"GUESS"!
Also from this manufacturer based in Canada.

 

[ThatDogDontHunt]

And? You originally asked about advancements over your 24 year old computer. There are plenty of advancements. Not all advancements are aimed at diver safety. Many are aimed at convenience, ease of use and visibility. As I mentioned, algorithm based improvements are at least intended to enhance safety. How much is difficult To judge, but 16 compartments vs 8 compartments is certainly not a step backwards.

And regarding what other information you need. I’m not sure what you need. However, I like having GTR and SurfGF displayed on my computer in addition to the typical. Required, no. But very nice to have.

Buhlmann published his research in 1983 and died in 1994.

Bühlmann decompression algorithm - Wikipedia

en.m.wikipedia.org

Albert A. Bühlmann - Wikipedia

en.m.wikipedia.org

 

[ThatDogDontHunt]

Buhlmann published his research in 1983 and died in 1994.

Bühlmann decompression algorithm - Wikipedia

en.m.wikipedia.org

Albert A. Bühlmann - Wikipedia

en.m.wikipedia.org

And for those who like to connect the dots...and maybe give Uwatec computers a bit of credit...

The co-author of Buhlmann's book is E. Völlm.

Tauchmedizin by Buhlmann - AbeBooks

Tauchmedizin : Barotrauma Gasembolie Dekompression Dekompressionskrankheit Dekompressionscomputer by Bühlmann, Albert A. and a great selection of related books, art and collectibles available now at AbeBooks.co.uk.

www.abebooks.co.uk

Enrst went on to found a successful company called Dynatron. Much later he failed to repeat his success with UEMIS.

Dream Jobs 2010: Ernst Völlm, Rapture of the Deep

Ernst Völlm makes the dive computer that every aquanaut wants

spectrum.ieee.org

Dynatron's dive computer was manufactured by Uwatec.

From an article by Buhlmann's son...

"In order to produce an energy-efficient dive computer, the number of arithmetic operations had to be kept small. Unlike today, the computing capacity of the hardware available at the time was limited. Together with my father, Dynatron AG developed a calculation model that was limited to six tissues. In 1987 the no-stop dive computer «Aladin» was announced. Just one year later, the «Aladin Pro» was announced as the next development stage. The calculation model was revised by Ernst V. Völlm, Markus Mock, both Dynatron AG, and my father. Aladin Pro was a full-fledged decompression computer. With the Aladin Pro, Uwatec AG has established itself as the world market leader in the rapidly growing dive computer market. Together with Dynatron AG, my father then worked on the next stage in the development of dive computers, the “intelligent” dive computer. The calculation model with the name ZH-L8 ADT was developed for this purpose. This computer model took into account the variability of the blood flow to the organs, muscles and skin due to exertion and cooling by integrating a micro gas bubble system. The Aladin Air X dive computer was presented to the international press on January 25, 1994 at the «Boots» in Düsseldorf by representatives of Uwatec AG, Dynatron AG and my father."

 

[KenGordon]

Please actually read post #60 understand the point I was trying to make. And yes me personally I would rather dive with a 16 compartment algorithm then an 8 compartment algorithm. Also nowhere in the post did I mention that since ZHL16 is based of off 16 different tissue compartments meaning 16 different M-Values that this is twice as safe as some have suggested. There is not relationship to the amount of compartments to the percentage of safety.

The 16 compartments is simply just representations of likely values of T halfs spread through the body. So yes in theory a 16 compartment model is calculating 8 additional compartment more then the 24 year old Uwatec hybrid 8 compartment model. Please remember that each representative compartment is calculating the inert gas pressure in each compartment during on-gassing or off-gassing. This is just giving the computer more data points.

When you start to do several sub 100m dives a year you want to have as accurate tissue loading model as possible.

Only one compartment matters in Buhlmann, the worst one.

It makes almost no difference at all if you skip half the compartments. What sort of matters is the first and last ones are there, but nobody every go limited by the last compartment of zhl16. Having the first 4 and a couple of longer, for next day loading, ones would do.

Some tables are based one three compartment.

Pretty much all the non GF computers are running 8 or 9 compartment dissolved gas models. At the last dive show I was at there was a presentation showing one of those being crushed at well over 200m.

This is a bit less important than the polygon count in game models.

Bluetooth and a decent screen, without stupid and useless battery life, are what have improved. Literally nothing has happened with algorithms in decades.

 

[Wibble]

Bells and whistles have no contribution to safety.

"This computer is capable of calculating deco stop requirements. These calculations are at BEST a GUESS of the real physiological decompression requirements!
"GUESS"!
Also from this manufacturer based in Canada.

ALL decompression algorithms are MODELS to simulate the body's response to pressure changes.

ALL decompression algorithms are based upon a statistical model -- normal distribution -- based upon research of how people show signs of decompression sickness for a specific profile.

ALL decompression computers follow these models and are not aware of the specific circumstances of that person, environment nor psychological and physiological state.

The diving community, and especially the technical diving community, has generally developed a consensus around the Buhllmann + Gradient Factors algorithm. Other algorithms are commonly used in the shallower recreational diving community (e.g. PADI's RDP).

 

[Belzelbub]

Bells and whistles have no contribution to safety.

"This computer is capable of calculating deco stop requirements. These calculations are at BEST a GUESS of the real physiological decompression requirements!
"GUESS"!
Also from this manufacturer based in Canada.

And? This statement is accurate. Any dive computer is making a guess. To say otherwise would be at least obscuring the truth. Dive computers use theoretical models. They have no idea what is happening with the diver’s body. It is an assumption based on research, but it is still an assumption.

You originally asked about advancements made in 24 year. There are plenty. Many of them are “bells and whistles,” but they are still advancements. Different algorithms are definitely a step forward in better safety.

I get it, you don’t want to buy a Shearwater. Don’t buy one. It’s good that we all have choices. The individual diver can take a look at all the features available and decide which ones provide value to them. Value is not just a question of safety, it includes convenience and additional information available.

Buhlmann published his research in 1983 and died in 1994.

Understood. However, it’s been more recent when dive computers were able (or their manufacturers were willing) to implement the algorithm developed.

 

[dmaziuk]

How would you calibrate more compartments?

That depends: if you make more compartments in the original 4..635-minute interval,

a = 2 * t ^ (-1/3)
b = 1.005 - t (-1/2)

where t is the compartment's half-time (it may work to ZH-L12's 2.65 min too, I haven't looked).

This is the "A" set that was later empirically found to be a bit too "aggressive" (for the target DCS incidence) in the middle compartments so those were adjusted, making "B" and "C" sets. One can back-port the adjustments fairly simply using e.g. curve-fit to one's ZH-L32 or ZH-L1024 or whatever; of course the subsequent goat trials will be a bit more problematic.

If you want to go past 635 minutes on the slow end, all bets are off.

 

[boulderjohn]

Buhlmann published his research in 1983 and died in 1994.

Bühlmann decompression algorithm - Wikipedia

en.m.wikipedia.org

Albert A. Bühlmann - Wikipedia

en.m.wikipedia.org

Buhlmann's work did not include the very popular feature known as gradient factors. Those were created by Erik Baker in the 1990's but did not become a factor until much later. I don't know of any computers using them at all until about 10 years ago--if that. Today it seems like that is the hottest topic of conversation in the world of dive computers.

A feature only a couple years old is SurfGf--the GF high you would have if you surfaced immediately. This beats the heck out of the old safety stop for determining when you should surface after an NDL dive. I am about to go on an extended recreational dive trip with two friends who use older conventional computers. I am sure we will finish each dive the way we did the last time I dived with them--they will be counting down the last seconds of their safety stops while I wait for them to do so on dives where I know from my SurfGF factor that a safety stop is simply not necessary. On our last trip, we used EANx 36 on relatively shallow reef dives, and when we reached safety stop depth, my computers had my SurfGF in the 50s--absolutely no reason not to go right to the surface. There's no harm in doing unnecessary safety stops, so I stayed with them while they followed their computers.

 

[BlueTrin]

If you want to go past 635 minutes on the slow end, all bets are off.

I’ll make sure to keep that in mind when planning

 

[dmaziuk]

I’ll make sure to keep that in mind when planning

Don't forget to bring plenty of water: 2.6 days to get there is already too close to "the law of 3s", and then there's however long it takes to come back up.