More conservative algorithm = how much bottom time?

Suppose 1 is the least conservative computer algorithm out there and 10 is the most conservative. What is the actual difference between bottom time on a dive say to 50 feet, flat profile. Tables would say 80 minutes is the NDL. How much bottom time will algorithm 1 give you? How much bottom time do you really give up by using algorithm 10? Will algorithm 1 always say 80 minutes?

Understanding that there is a lot of in-between and that some brands are more conservative than others, what is the least conservative computer out there? The most? (outside of cave or tech-level stuff) I'm trying to figure out what the "cost" of diving a particular level of conservatism is in actual bottom time foregone.

Cheers, OCBB

The answer to your question presumes that someone has ALL of the computers on the market and that all of the credible algorithms are represented. Seems unlikely.

Nitek Duo SF=0 -> 50' 68 minutes
Nitek Duo SF=2 -> 50' 53 minutes

The Nitek Duo lets you pick your own Safety Factor

Aladin Prime 50' 66 minutes
It doesn't seem that a safety factor can be programmed into the Aladin Prime
At least I didn't see it in the manual or on the screens.

I have no idea what algorithm the Aladin Prime uses but the Nitek Duo uses Buhlmann ZH-L16 which doesn't mean anything to me.

Then there is the LiquiVision X1 Liquivision Home which comes as bare iron and the user can choose among at least 3 different sets of software.

FWIW, the 1987 NAUI tables show 50' 100 minutes and provide deco information out to 160 minutes (21 minute deco).

The 1989 NAUI tables show 50' 80 minutes and provide deco information out to 100 minutes (5 minutes deco).

Richard

Oceanic Geo 50' = 81 minutes

ocbeachbum,

You've opened the proverbial can of worms regarding decompression algorithm. This is a complex question regarding 1st dive, repetitive dive, profile, gas... Conservative factor choice, deep stop, safety stop, etc, are all additional variables.

For 1st dive on air at 50 feet: Pelagic Pressure Systems (Oceanic et al.) 80 minutes, Seiko (Dive Rite Nitek Duo et al.) 64 minutes, Cochran 83 minutes, Uwatec 72 minutes, Suunto 69 minutes. The comparable values vary reasonably widely by depth.

If you're interested in a more thourough understanding, I would recommend Deco for Divers, Mark Powell, Aquapress, 2008, as a good start. I'm quite interested in the topic and could offer additional reading by PM.

Good diving, Craig

I suggest you go to the subforum (below) on computers, and you will see that similar questions have been asked quite a few times. I suggest that you search through some of the past threads there for a while and then reformulate your question to get exactly the information you need.

Thanks to all who responded. I was really just looking for a range of how much different algorithms varied and if there was some silver bullet explanation as to how to determine one's optimal algorithm (similar to a risk-return analysis picking stocks). Unsurprisingly, there isn't, but you've pointed me in the right direction. Cheers.

Lippmann and Mitchell's Deeper into Diving has a nice table in it, comparing NDL times at various depths for various algorithms, and if I remember it correctly, the variations could be as much as 12 minutes or so at certain depths.

There is no optimal algorithm. None of them really models what's happening inside the human body. They make different physical assumptions and are subjected to differing amounts of empirical validation. As Dr. David Sawatzky observed in a column in Diver magazine, the biggest reduction in DCS risk came with Haldane's original observations. Everything we do nowadays is chipping away at the very fine edges, because DCS has become a rare occurrence in recreational diving.