Please help me understand my computers conservatism : Nitek Q and Buhlmann ZLH16

My Nitek Q (which I got in a contest) has 3 pre-programmed conservatism factors in it. I have kept it on Cons2 which is the most conservative and the default setting since I bought it. This weekend when diving past 100ft I noticed that I was running out of NDL much quicker than my buddies Hollis DG03. It seemed like it was extra conservative. According to tables I felt like I should have had at least 5 or more additional minutes of NDL.

I don't want to blindly switch my conservatism in my computer without some understanding of what it means.

My computer uses Buhlmann ZLH16 Algorithm with the following gradient factors:
Cons0 = 75/95
Cons1 = 40/100
Cons2 = 30/75 (current setting and the default setting)

Can you help me to understand the gradient factors or point me to some additional reading online?

I would rather my computer ran more "neutral" as far as conservatism is concerned and I will add my own conservatism by not getting close to NDLs or diving Nitrox on air profiles etc.

I should add this all pertains to Recreational No Deco diving. Next year I may take Advanced Nitrox and Deco procedures.

00wabbit:

My Nitek Q (which I got in a contest) has 3 pre-programmed conservatism factors in it. I have kept it on Cons2 which is the most conservative and the default setting since I bought it. This weekend when diving past 100ft I noticed that I was running out of NDL much quicker than my buddies Hollis DG03. It seemed like it was extra conservative. According to tables I felt like I should have had at least 5 or more additional minutes of NDL.

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Nearly any dive computer you can buy, will produce a reasonably safe dive if you follow it.

All the different computers have their own take on various algorithms, however DCS is rare enough that there isn't any statistical evidence to say that computer X is safer than computer Y or algorithm X is better/safer than algorithm Y.

flots.

Disclaimer - I do not own nor know the workings of this particular computer. What follows is just my experience with my Suunto Cobra and Cobra3 which are famous for being conservative.

Each dive computer company uses their own program which may or may not resemble any certification agency dive table. The program reflects that companies take of current Dive science and their legal teams advice. Some dive computers are famously very conservative, others famously liberal. The personal settings of the computer will allow you to select regular, conservative, or ultra conservative levels depending on your DCS risk factors (one or more of the following: age, previous DCS, injury, scar tissue, clogging of your plumbing, physical conditioning or more importantly lack there of, cold water, work load etc to name a few).

Yes at a setting of 2 your computer would be very conservative. So here are in the most generic terms the levels:
How much each setting above 0 will deduct from your NDL will vary by manufacturer and with depth.
1. Standard or P0 - this level (P0 on Suunto) is the factory default setting and will give you the most bottom time. If you are have no risk indicators for DCS (see your dive manual for risk factors. Think of this a the standard multilevel dive table.
2. Personal Setting 1 (P1 on Suunto). This will reduce your NDL by a bit. How much depends on the manufacturer of your dive computer. Think of is as if you were using a dive table to plan and execute your dive using the next deeper depths than the one your are actually diving in your calculations or deducting 05 minutes from your allowable NDL dive time.
3. Personal setting 2 (P2) on Suunto). This will reduce your NDL by a more. How much depends on the manufacturer of your dive computer. Think of it here as adding 2 next deeper depths to your dive plan/calculations or deducting 10 minutes from your actual allowable NDL time.

Which setting is right for you? That depends on you. How conservative (far from the theoretical edge) you want to be? Do you have risk factors? What are todays conditions? The setting you select may change from day to day or dive to dive. I am 60 years old and fell out of airplanes for 8 years. I have damage to my knees, ankles and other places and I have had DCS. I choose to dive P1 most days. But that is me, you decide what you want to do. I hope this helps.

00wabbit:

My computer uses Buhlmann ZLH16 Algorithm with the following gradient factors:
Cons0 = 75/95
Cons1 = 40/100
Cons2 = 30/75 (current setting and the default setting)

Can you help me to understand the gradient factors or point me to some additional reading online.

Click to expand...

http://www.shearwater.com/wp-content/uploads/2012/08/No-Stop_Time.pdf

http://www.shearwater.com/wp-content/uploads/2012/08/Deep-Stops.pdf

Gradient Factors for Dummies - Rebreather World

flots am:

Nearly any dive computer you can buy, will produce a reasonably safe dive if you follow it.

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Diving 75/95 is reasonably safe?

30/75 is pretty conservative. I use 30/85 on my Shearwater. On NDL dives it roughly correlates to surfacing in the green(not yellow) on my aeris (Oceanic) computer.

Can you choose your own gradient factors on the Niteq, or are you stuck with DiveRites choices?

i'm stuck with these 3 choices. I could pay for more options but I'm not going to do that.

Nuribromanski:

Diving 75/95 is reasonably safe?

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I have no idea what that is, but if it's on a recreational computer, it's safe enough that the manufacturer hasn't been sued into the dirt yet, and divers aren't washing up dead on the beach.

Have you been bent with it?

Nuribromanski:

. . .

Gradient Factors for Dummies - Rebreather World

Click to expand...

That's a great article on Gradient Factors. The book Deco For Divers stops just shy of the fuller explanation (with examples) in that article.

OP: If you're interested in learning more about decompression principles in general, Deco For Divers is the number 1 recommended book. To understand M-values, which are mentioned in the Gradient Factors For Dummies article, read Deco For Divers!

to understand what gradient factors are about you should have an idea what m-values are
http://www.cavecountrydiving.com/storage/Understanding M-values.pdf
Shearwater used to have 30/85 as factory setting on their Predator, the Petrel comes with 30/70 as default, so they obiously decided 30/85 was a little aggressive.

This article might help you better understand

http://www.tek-dive.com/portal/upload/M-Values.pdf