Odds he’s reading surface GF as CNS?
Wanna stay down longgerrr
- Thread starter Swedinsidemount
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Blackcrusader
Contributor
Now I can imagine where the problem comes from. An advanced computer providing too much numbers...
My Cressi Leonardo does not have all these additional parameters, it only shows me current depth, max depth, current time and remaining time to NDL. There is an alarm if I exceed the MOD of my gas (pretty impossible, as I dive air and I never exceed 50m). That's all I need...
Why should I worry about CNS% (whatever this means) if I stay within the MOD of my gas?
I admit that, not being a technical diver, perhaps I am missing some piece of information here.
The OP wants to extend his bottom time, and I already suggested that the simple way to get this is to go beyond the NDL and plan for some deco stops, still using the back gas. Plain simple.
An example: one of my favourite "square" profiles at Maldives was 30 minutes at 30m. This is beyond NDL, which should be 20 minutes at 30m. The US Navy table gives you a 3 minute deco stop at 3m. So this is actually a deco profile which extend your bottom time by 50% and requires just very minimal deco, substantially the same as the standard "safety stop" of 3 minutes at 5m, which I always do in any case, before the "mandatory" deco stop of further 3 minutes at 3m.
In practice, instead of the NDL dive of 20 minutes at 30 meters, plus 3 minutes at 5m of "safety stop", I make a dive of 30 min at 30m, with a "safety stop" of 3 min at 5meters, followed by a deco stop of other 3 minutes at 3m, and then a very slow ascent from 3m to 0m in about one minute.
I was doing this with a 15-liters steel charged at 200 bar, and usually when back on the dhoni boat the SPG was around 80 bar. Pretty safe, in my evaluation.
For me this is the reasonable way of extending significantly bottom time (50% more) without changing substantially anything in the equipment employed. I do not think that this way of diving requires a lot of training, it was included in the first level course I did back in 1975.
My Cressi Leonardo does not have all these additional parameters, it only shows me current depth, max depth, current time and remaining time to NDL. There is an alarm if I exceed the MOD of my gas (pretty impossible, as I dive air and I never exceed 50m). That's all I need...
Why should I worry about CNS% (whatever this means) if I stay within the MOD of my gas?
I admit that, not being a technical diver, perhaps I am missing some piece of information here.
The OP wants to extend his bottom time, and I already suggested that the simple way to get this is to go beyond the NDL and plan for some deco stops, still using the back gas. Plain simple.
An example: one of my favourite "square" profiles at Maldives was 30 minutes at 30m. This is beyond NDL, which should be 20 minutes at 30m. The US Navy table gives you a 3 minute deco stop at 3m. So this is actually a deco profile which extend your bottom time by 50% and requires just very minimal deco, substantially the same as the standard "safety stop" of 3 minutes at 5m, which I always do in any case, before the "mandatory" deco stop of further 3 minutes at 3m.
In practice, instead of the NDL dive of 20 minutes at 30 meters, plus 3 minutes at 5m of "safety stop", I make a dive of 30 min at 30m, with a "safety stop" of 3 min at 5meters, followed by a deco stop of other 3 minutes at 3m, and then a very slow ascent from 3m to 0m in about one minute.
I was doing this with a 15-liters steel charged at 200 bar, and usually when back on the dhoni boat the SPG was around 80 bar. Pretty safe, in my evaluation.
For me this is the reasonable way of extending significantly bottom time (50% more) without changing substantially anything in the equipment employed. I do not think that this way of diving requires a lot of training, it was included in the first level course I did back in 1975.
Blackcrusader
Contributor
The problem only comes in when a diver uses a computer and does not understand all of it's features. This is not an issue of the computer providing too many numbers. Also on many computers you can choose what to display on screen. On my Perdix my screen is set to show NDL and PO2 but not CNS in addition to depth time TTS etc. Also if I do exceed NDL and go into deco often you can clear the deco obligation by going shallower during the dive. I can push a button to go to a screen to show CNS at any point on my dive. My Perdix is set for a 6m 5 minute safety stop. The Perdix will show DECO CLEAR in the top right corner if you have been in deco and CLEAR if you complete safety stop not exceeding NDL. It will then add minutes so often I may stay at 5m for 15 minutes as I am often taking photos on the reef and often see + 10 minutes on screen.
OP
Swedinsidemount
Contributor
ok sorry for any misunderstanding or unarrurate info. I'm currently in the Keys and don't have exact numbers in front of me but here is a recent dive off Hillsboro Ledge in FortLauderdale.
Here is my gear:
-Zeagle 911 #65 WITH B/P
-OTS FFM
-Single S133 or twin AL63s
*this was a repetitive dive previous one was like 50feet for half an hour or so
-70feet
-40mins
-CNS% at end 60%
NUMBERS ARE NOT EXACT MAY VARY 5-10 UNITS
But let me rephrase my original question:
My CNS% and BT limit Reaches in ex:50 minutes . How can i extend my Bottom Time "limit" and MOD , and what equipment should i acquire or upgrade to make that happen , if at all .
T H A N K S < TG >
Here is my gear:
-Zeagle 911 #65 WITH B/P
-OTS FFM
-Single S133 or twin AL63s
*this was a repetitive dive previous one was like 50feet for half an hour or so
-70feet
-40mins
-CNS% at end 60%
NUMBERS ARE NOT EXACT MAY VARY 5-10 UNITS
But let me rephrase my original question:
My CNS% and BT limit Reaches in ex:50 minutes . How can i extend my Bottom Time "limit" and MOD , and what equipment should i acquire or upgrade to make that happen , if at all .
T H A N K S < TG >
And what gas did you dive that on? And what computer / algorithm are you using. Because I've done similar dives on air and haven't got anywhere close to that level of CNS
Sorry, this makes no sense. Even if you were using 36% Nitrox, using tables so ALL the numbers will be much more conservative than your computer, I can't find any way for you to have accumulated more then 30% CNS.ok sorry for any misunderstanding or unarrurate info. I'm currently in the Keys and don't have exact numbers in front of me but here is a recent dive off Hillsboro Ledge in FortLauderdale.
Here is my gear:
-Zeagle 911 #65 WITH B/P
-OTS FFM
-Single S133 or twin AL63s
*this was a repetitive dive previous one was like 50feet for half an hour or so
-70feet
-40mins
-CNS% at end 60%
NUMBERS ARE NOT EXACT MAY VARY 5-10 UNITS
As the previous poster said, what gas were you using, and what computer/algorithm?
Alekseolsen
Contributor
You could run that dive (not repetitive, but doesnt matter much for CNS) on EAN45 without getting anywhere close to those CNS number.. (I do not recommend diving with a planned PO2 above 1.4 though)
80 feet for 45 minutes with EAN45 would do the trick, but thats close to 1.6 bar PO2
Who does dive with EAN45 though??!
80 feet for 45 minutes with EAN45 would do the trick, but thats close to 1.6 bar PO2
Who does dive with EAN45 though??!
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My guess is he was NOT diving with anything like 45%, but his computer may have been set to that!
CCR.
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