Your Gradient Factors?

[Manatee Diver]

That means that for a scientist, "theory at best" is pretty darn good. If a concept gets labeled as a theory, it is pretty thoroughly accepted.

I was using the more commonly accepted term. The scientific term would be hypothesis.

 

[Celt]

Shearwater will let you run 90/90. Technically, that shouldn't bend you. But I wouldn't try it.

I’ve never owned a dive computer could you give an example of a 90/90 dive profile just to give me an idea of what you’re talking about, thanks.

 

[helodriver87]

I’ve never owned a dive computer could you give an example of a 90/90 dive profile just to give me an idea of what you’re talking about, thanks.

It means you're using GF Low and High values of 90% of the maximum m value to control your ascent profile. It's basically 10% short of the theoretical bent/not bent line. Very aggressive.

 

[boulderjohn]

It means you're using GF Low and High values of 90% of the maximum m value to control your ascent profile. It's basically 10% short of the theoretical bent/not bent line. Very aggressive.

That's one way of thinking about it. Another way of thinking about it is you are diving within 10% of the Buhlmann NDL limits--very conservative.

For NDL dives, the first 90 is not relevant, and the second is used fairly commonly.

 

[Celt]

It means you're using GF Low and High values of 90% of the maximum m value to control your ascent profile. It's basically 10% short of the theoretical bent/not bent line. Very aggressive.

Okay so a 10% error would put you over your deco ceiling, and possible dcs

 

[helodriver87]

That's one way of thinking about it. Another way of thinking about it is you are diving within 10% of the Buhlmann NDL limits--very conservative.

For NDL dives, the first 90 is not relevant, and the second is used fairly commonly.

This is true. I was only looking at it from a planned deco perspective where it would be pretty aggressive.

 

[helodriver87]

Okay so a 10% error would put you over your deco ceiling, and possible dcs

Not really error so much as variability. What bends you one day might not the next. But when you're that close to the theoretical limit, you're gonna find yourself on the wrong side of that line more frequently.

 

[Celt]

So a computer is plotting a path or column of water it believes is your best route to the surface and you can decide where on this path is best for you depending on how you might feel or the dive conditions at the time, have I that right.

 

[boulderjohn]

No decompression algorithms are based on the belief that if you violate them you get DCS. They are based on research indicating that an overwhelming majority of divers will be OK at those limits, but as those limits are violated, the odds start getting worse.

 

[helodriver87]

So a computer is plotting a path or column of water it believes is your best route to the surface and you can decide where on this path is best for you depending on how you might feel or the dive conditions at the time, have I that right.

Gradient factors are essentially guardrails that your ascent profile is built between. Most people don't change them regularly. You really just have to figure out what works best for you, balancing the length of deco with how you feel after a dive. People do tend to mess with GF hi more frequently though, as it will extend your shallow stop time. It's common at altitude, in remote places, or anytime someone wants to pad the O2 a bit for whatever reason.