IANTD nitrox table

[Jason A]

I was recently nitrox certified by IANTD. I subsequently purchased two yellow plastic roll-up nitrox diving charts.

The first chart is a IANTD/NOAA nitrox I 32% chart that corresponds exactly to the actual NOAA chart.

My problem/concern is with the 36% chart. It is strictly an IANTD chart with no mention of NOAA.

The NDL’s are much more conservative. For instance, the NOAA chart at 40 feet shows a NDL of 405 minutes. The IANTD chart shows a NDL of 154 minutes.

Also, the repetive groups are different. A dive to 60 feet for 40 minutes shows a D pressure group on the IANTD chart, whereas, the NOAA chart shows an F group.
After a thirty minute surface interval I would still be at F with the NOAA, while the IANTD puts me at A.

I understand that agencies use different charts, but I’m just wondering why these are so different. I tried searching this board but couldn't find anything related.

Which one would you, or do you, use?
Thanks

 

[mer]

I was recently nitrox certified by IANTD. I subsequently purchased two yellow plastic roll-up nitrox diving charts.

The first chart is a IANTD/NOAA nitrox I 32% chart that corresponds exactly to the actual NOAA chart.

My problem/concern is with the 36% chart. It is strictly an IANTD chart with no mention of NOAA.

The NDL’s are much more conservative. For instance, the NOAA chart at 40 feet shows a NDL of 405 minutes. The IANTD chart shows a NDL of 154 minutes.

Also, the repetive groups are different. A dive to 60 feet for 40 minutes shows a D pressure group on the IANTD chart, whereas, the NOAA chart shows an F group.
After a thirty minute surface interval I would still be at F with the NOAA, while the IANTD puts me at A.




I understand that agencies use different charts, but I’m just wondering why these are so different. I tried searching this board but couldn't find anything related.

Which one would you, or do you, use?
Thanks

Do you have NOAA air tables and like them? Remember from your nitrox class how to convert your depth on a certain EANx mix to an equivalent air depth (EAD). Then use that EAD and air NDL to plan your dive.

 

[Charlie99]

Look at the IANTD charts and tables webpage.

It sounds like you have the (old) NOAA Nitrox I table, and the new IANTD Nitrox Diving & Decompression Table for EAN36 -- C-3816.

The new tables are based upon the Buhlmann ZHL16 algorithm. the NOAA ones are based upon the Workman limits of the USN tables.

They will have different repetitive groups and you CANNOT go back and forth between them. You need to get the air table (C3800 IANTD Openwater Air Table) and 32% tables to match your EAN36 table.

Or just use an air table and equivalent depths for all calculations.

 

[Jason A]

Thanks guys,

When taking the class the instructor made no mention of the IANTD table. He told me that they used the Navy air table so that's what I used for the class. I have been using the PADI table prior to this.

In using the EAD from the Navy table all the measurements and calculations were equal to the IANTD tables.

I guess I'll get a new 32% table from IANTD.

Any problems or concerns with the Navy air table?

Are the NOAA tables outdated?

Thanks.

 

[StSomewhere]

Any problems or concerns with the Navy air table?

Are the NOAA tables outdated?

Thanks.

Short answer: Yes.

Longer answer: Technically, like Charlie said, it's the Workman limits that are outdated, since the old NOAA tables and Navy tables use those limits they are, by extension, outdated. Maybe your instructor had the old NOAA-based IANTD tables and that's why you got that?

I agree, its easiest if you have the Buhlmann IANTD tables for air, 32% and maybe 36% and 40% if you are so inclined. The interchangability is worth the minimal extra cost. If you instructor doesn't have all the Buhlmann-based IANTD tables you can get them from DiveRiteExpress.

 

[Charlie99]

I guess I'll get a new 32% table from IANTD.

Don't forget to also get the new air table also. Using that, and an equivalent depth table, you can handle planning for the day you get 34% or something else other than 32 and 36.

 

[Jason A]

OK, thanks again.

It looks like I'll throw the navy table in the trash and start over.

Just to make completely sure: I need a new 32% table, but I keep the 36% that I have. I also add a IANTD air table.

I noticed on the diveriteexpress site that there are two different air tables. One is a 75% accelerated deco schedule and the other is 50%. I don't see the C3800 model table as posted above. Which one should I get? Obviously, I don't do any decompression diving.

Or, perhaps, since I am getting almost all new tables anyway there is something better that you guys use instead of IANTD?

Using any air table and the EAD method would be OK too, I guess, but more work. Not that I am opposed.

Sorry for all the questions. After going through this and finding that I was sold the wrong tables I question my instruction.

Jason

 

[StSomewhere]

Here's what I have:

C-3901 Air (used for EAD conversions and comparison only)
C-3905 32%
C-3907 36%

The "accellerated" deco schedules on the back aren't really important at the recreational nitrox level (i.e. you won't use them for NDL dives). If/when you move onto advanced nitrox then you may be using a deco gas separate from your back gas and those will come into play. FWIW, the tables listed above all have the >=50% schedule on back.

The Navy table would be useful to compare to other tables, IMO, but that's about it.

 

[DiveGolfSki]

OK, thanks again.

It looks like I'll throw the navy table in the trash and start over.

Just to make completely sure: I need a new 32% table, but I keep the 36% that I have. I also add a IANTD air table.

I noticed on the diveriteexpress site that there are two different air tables. One is a 75% accelerated deco schedule and the other is 50%. I don't see the C3800 model table as posted above. Which one should I get? Obviously, I don't do any decompression diving.

Or, perhaps, since I am getting almost all new tables anyway there is something better that you guys use instead of IANTD?

Using any air table and the EAD method would be OK too, I guess, but more work. Not that I am opposed.

Sorry for all the questions. After going through this and finding that I was sold the wrong tables I question my instruction.

Jason

You could also consider moving up to RGBM tables. Using your previous example, 40 FSW on EAN 36, the Naui RGBM tables have a NDL of 380 minutes.

 

[Jason A]

You could also consider moving up to RGBM tables. Using your previous example, 40 FSW on EAN 36, the Naui RGBM tables have a NDL of 380 minutes.

That sounds OK too. Forgive my ignorance but is there any other benefit to using the RGBM? I have read a few posts about it but don't really understand. I also remembered reading that it hasn't been accepted by the military yet and that is supposed to be a negative according to some.

I am slowly moving towards decompression diving and would rather not have to buy tables over again. But, I guess that is really inconsequential considering the other associated costs.