NiTec Duo NDL for air, is this right?

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divenutny

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Scuba Instructor
Divemaster
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Location
Brewster, NY
# of dives
1000 - 2499
Hi - Just purchased a NiTec Duo. While playing with the air NDL (21%), comparing them to a Suunto Eon, I noticed the NiTec was more conservative on shallow depths than the Eon. I expected the NiTec to be less conservative. Maybe the NiTec is better at depths over 100 ft, multi level and decompression dives. This remains to be seen. Altitude set to sea level. Duo has salt water/fresh water setting, EON does not. I recent became Nitrox Certified and I wanted to get away from air integration. Wanted a computer that would handle decompression dives, should I decide to choose to start decompression diving. Felt Dive Rite was a better choice over Cochran. After reviewing the air NDL's, I wonder if I made a mistake.

ft Eon Duo Duo
Fresh Sea
40 120 109 100
50 70 68 64
60 51 49 45
70 36 36 34
80 28 26 24
90 22 20 19
100 17 17 16
110 13 14 13
120 10 11 11
130 9 10 9

I sent a note to Dive Rite. I suspect they will advise me everything is fine. Just trying to see if anyone else noticed this type of programming.

If anyone else has the NiTec, could they check their NDL's against my chart? I am wondering if these ndl's match yours. I'm trying to determine if this computer has an issue BEFORE I place it in the water.

I usually review a chart when I am planning a dive. Since I an over 50, it might be best to take a more conservative approach. I have dove 60 feet for 50 minutes, I wonder if the NiTec will force a safety stop, which I would do regardless, where the Suunto would not expect a safety stop. I know the Navy charts and PADI charts. However, if I need to keep second guessing my equipment, time to get better stuff. In this case, return it.

Thanks - Tom
 
My Nitek duo reads the same as yours. I always leave the setting on fresh water to get the longer times. I have done decompression dives and nitrox dives with this computer without any problems. I have taken it to 185 feet also without issues.
I also leave it on the least conservative setting.

I bought it for the two gas switching function and am satisfied with it.
 
I used to use a Tusa IQ 700 (identical to the DiveRite Duo) before it died on me. I liked it a lot,reasonably conservative but not excessively so. Dont see any need to "second guess" it.

The deco algorithm is very Buhlmanish. i.e. does not know anything about deep stops.I would not use it for deco dives without applying the manual override.
 
TheDivingPreacher:
I always leave the setting on fresh water to get the longer times.
That won't have any effect. It changes how many feet shown on the display, but for a given PRESSURE the computer will always have the same NDL.

Or to put it another way, for a given number of feet displayed, the fresh water NDL will be larger, but when set on fresh water the displayed feet will be 3% higher while you are diving. That cancels out the increase in NDL.
 
Thanks for the feedback. Sometimes I over analyze things too much. Glad to hear other people are happy with this model. Time to get wet and try it out.
 
Charlie99:
That won't have any effect. It changes how many feet shown on the display, but for a given PRESSURE the computer will always have the same NDL.

Or to put it another way, for a given number of feet displayed, the fresh water NDL will be larger, but when set on fresh water the displayed feet will be 3% higher while you are diving. That cancels out the increase in NDL.


Thanks!
Learn something every day. I never researched it but thought there must be some difference in the speed of ongassing in salt vs fresh water. Thought it was kind of strange though :huh:
 
In another dive computer related thread, I received a response that Oceanic has their 60 ft NDL for air at 57 minutes. The thread was someone asking if a watch/computer existed that follow the US Navy Dive tables. Although I am hearing that the NiTec is working correctly showing a 60 ft air NDL at 45 minutes for salt water, I still wonder if something is wrong with this piece of equipment. I have been in touch with Dive Rite. They noticed this thread. I will pass on their response.

Originally Posted by scubatoys
The US navy tables show a 60 ft dive for 60 minutes... An Oceanic or Aeris computer will show a 60 for 57... So that's pretty close.
 
divenutny:
In another dive computer related thread, I received a response that Oceanic has their 60 ft NDL for air at 57 minutes. The thread was someone asking if a watch/computer existed that follow the US Navy Dive tables. Although I am hearing that the NiTec is working correctly showing a 60 ft air NDL at 45 minutes for salt water, I still wonder if something is wrong with this piece of equipment. I have been in touch with Dive Rite. They noticed this thread. I will pass on their response.

Originally Posted by scubatoys
The US navy tables show a 60 ft dive for 60 minutes... An Oceanic or Aeris computer will show a 60 for 57... So that's pretty close.

Seems to be some confusion here. Just because a computer has an NDL of 45 minutes at 60 feet whereas the navy tables are 60 minutes does not make that computer "wrong" Very few (informed) divers would choose to follow the Navy Tables.

If you want to dive aggressively buy an Oceanic/Aeris computer rather than the DiveRite,but remember that even though the computer may say it is OK to surface your body may disagree!

I have used an Aeris computer for many years. I am of the opinion that routinely diving it all the way to the NDL and then surfacing with it nudging up against the red zone would be a pretty good way to get bent.
 
Although you can't see it before doing a dive (since the plan function doesn't allow for multiple dives), when you start doing repetitive dives the DR will be less conservative on the repetitive dives than the Suunto.
 
I'd say there are a few things you need to understand. :)
First -- a little about basic decompression, and second -- a little understanding about the computer itself.

The first thing you need to know about decompression is that it is NOT an exact science and there's a lot we don't know. See the numerous amount of tables out there--they all have different NDLs for a specific depth. Thus there's not one that's "right" and one that's "wrong". Thus, the Oceanic computer isn't "right" and the DiveRite computer isn't "wrong". Use whichever you're comfortable with.

About the computer--you haven't even been diving with it yet, but you're having questions/problems? Go take the darn thing diving. THEN if there are obvious issues (depth = 500ft as soon as you get in, etc) go talk to DiveRite.


US Navy tables were developed for 18 year-old males in peak physical condition, and are designed to have an "acceptable level" of DCS per certain number of dives. Most divers aren't physically fit 18 year-old males. You need to be conservative with your dive planning--don't push the limits.
If I recall correctly, the NDL for 30ft on the USN tables is 405 minutes. Do you seriously think that any computer manufacturer out there is really going to say that you have 405 minutes of NDL at 30ft? If you're worried about what the Navy tables have vs. what your computer has...why not just dive the Navy tables? (not that I'm advocating it; I'm just showing the logical conclusion to your thought process...)
Same goes for other depths:
35ft: PADI says 205 minutes, Navy says 310, NAUI & NOAA don't have a listing...
40ft: PADI says 140 mins, Navy says 200, NAUI says 130, NOAA says 200
130ft: PADI says 10, Navy says 10, NAUI says 8, NOAA says 10
140ft: PADI says 8, Navy says 10, NAUI & NOAA don't have a listing...
etc etc

I believe the other issue here is that you need to think, and not blindly follow what the computer tells you do to. THINK about it before diving. Right now you're in the "following what my computer says because it's my computer" stage. :) For example--you were talking about the NDLs for 60ft. How many new divers would probably hit the NDL before worrying about how much air they have left, using an Al80? Most likely: very few (if any).

Note that I'm not attacking you and I apologize if it comes across that way--just trying to get you to engage your brain, think about things, and maybe do a little research before saying that one computer is "right" and one is "wrong".
 
https://www.shearwater.com/products/perdix-ai/

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