Overshooting NDL and mandatory deco stops

[NAM001]

dive computers and the inequities between brands have always been a problem one makers medium is anothers low when it comes to conservatism. someone should make an industry standard that will say something like at 20min at 100 ft you hit 0 NDL.. and that on this computer the conservatislm setting to get that is _________ or the GF for that is ____. that way we all can get our puters on the same page and modify from a known base value to geve us a desired alarm. 100 ft can not have both 5 min and 15 min NDL. It wold be good to know that the dive table may say NDL is 18 so a couple of un intended minutes over on your computer does not actually mean you are in deco.

It never ceases to amaze me that so many divers will adjust their puters to gove them the greatest NDL as if the computer setting changes the science of ongassing and off gassing.

after all how hard would it be to say this setting is a match with the navy dive tables.

 

[seeker242]

after all how hard would it be to say this setting is a match with the navy dive tables

From the perdix Rec manual "The Low setting is similar to PADI and NOAA no-stop time tables for air and nitrox diving."

 

[Mike1967]

PADI

So 45/95 is similar to PADI?

 

[seeker242]

So 45/95 is similar to PADI?

Actually, low looks to be a bit more conservative than the tables. 100' NDL for air on low is 17 min.

 

[Mike1967]

Actually, low looks to be a bit more conservative than the tables. 100' NDL for air on low is 17 min.

Ok I've always had mine set to Med, it's going on Low now.
Cheers

 

[Jay]

Ok I've always had mine set to Med, it's going on Low now.
Cheers

FYI & my 2c: be cautious doing 3-4 dives/day / multi-days on that setting esp if 1hr SI. It'll eventually put you slightly more aggressive than DSAT. Info here: How to properly assess the relative conservatism of various algos/computers for Rec divers? I use 60/90 for everything just to leave it 'fixed' which is close to Z+

 

[RainPilot]

I believe they were talking about being in deco. I have never had my Oceanics in deco, but when I am close to the line I'll breath my tank as low as I have to to offgas as much as I can. I'm not too worried about going OOA at 15'.

Not aimed at you specifically, I see this comment a lot. Just something to bear in mind, although a CESA from 15' is not a major deal on a VERY benign dive, when you are inert loaded, that is the worst place to do a fast ascent. the pressure change gradient there is the steepest and it is where, in my tech training, the emphasis on a slow ascent rate has been the highest. The so-called "champagne phase"

 

[Storker]

Not aimed at you specifically, I see this comment a lot. Just something to bear in mind, although a CESA from 15' is not a major deal on a VERY benign dive, when you are inert loaded, that is the worst place to do a fast ascent. the pressure change gradient there is the steepest and it is where, in my tech training, the emphasis on a slow ascent rate has been the highest. The so-called "champagne phase"

When I was less experienced than I am today, I believed that some lethargy and sleepiness was quite normal after a dive or two. But I wasnt very experienced and tended to "cork" from my safety stop. Then I started trying to go slow on that last ascent from my safety stop. For some reason, around the same time I stopped being so sleepy after a dive or two.

I know that correlation doesn't necessarily imply causation, but since there also is a good hypothesis for the mechanism (silent bubbles), I'm pretty certain there was a causal relationship between those two observations. These days, I always try to go really s-l-o-w when ascending from my safety stop, and the post-dive lethargy has almost disappeared.

 

[RainPilot]

Yep, in my experience the Nitrogen Nap is a real thing. Once I moved to high PO2 gases and a sloooow ascent for the last few metres, it has all but disappeared for me too.

Oh, and by slow I mean a metre a minute or slower.

 

[Mike1967]

@Jay_Antipodean

Thanks