IANTD Tables

[Agility]

I am prestudying the course material for Advenced Nitrox and the manual states that the IANTD tables are Bühlmann based refined using EAD. I ran some of the tables through V-Planner and founds out that they match ZH-L16B with GF set to 75/75 pretty well.
In the manual the last pages are titled Advanced Recreational Trimix, probably they were put there to whet the student's appetite for more but the text leads to my question:

IANTD Advanced Recreational Trimix tables are based on the VPM algorithm.

Does anyone have the insight as to why IANTD uses Bühlmann tables for decompression diving on air and nitrox but VPM tables on trimix?

 

[JMBL]

To put it short and rather bluntly : VPM as a reputation of being 'bad' with air, but good with trimix. It's all a matter of deco strategy, each model having is own advantages and drawbacks, in the end I'm not so sure choosing one or the other is entirely based a 'scientific approach.

 

[Diver0001]

VPM as a reputation of being 'bad' with air, but good with trimix.

That's the first I've heard of that. Can you cite some sources, please. I'm sincerely curious.

R..

 

[JMBL]

That's the first I've heard of that. Can you cite some sources, please. I'm sincerely curious.

R..

As I've said, it's just a reputation. Meaning : I've met many divers here in France who told me I was crazy to use VPM for compute my run-times while diving trimix, and they went so far as to say it was useless while diving on air. It's a kind o opinion that's been circulating also on several forums here. As I was satisfied with VPM, I didn't care to research further and just thought : what's the hell ? So, I cannot give you any references about that.

 

[Agility]

I have seen (but cannot find the source) a graphic showing that VPM might exceed M-values on shallow stops, this is also the reason for the VPM/B with GF modification Shearwater offers on their V56 of the Predator firmware.

 

[Diver0001]

I see.

I've always used VPM for planning my longer incursions into deco, which in my case are 1/2 hour hangs max, and it's never given me an odd profile or any profile that was more aggressive than either the computer or the tables.

I know that most of the modern algorithms and, as far as I know, *all* of the bubble algorithms give increasingly aggressive results for dives deeper than 100m. Mark Ellyatt, for example, nearly killed himself using RGBM to plan a dive and to the best of my knowledge all of the divers doing really deep dives pad the shallow stops by a large margin. Maybe that's what you've been hearing. For a certain type of dive, it seems pretty clear that none of the algorithms we have are good enough. It doesn't seem to be limited to VPM though.

R..

 

[JMBL]

For a certain type of dive, it seems pretty clear that none of the algorithms we have are good enough. It doesn't seem to be limited to VPM though.

R..

You're right and I totally agree.

 

[NAM001]

When i did my iamtd rec trimix that tables matched the data from my shearwater using 30/85

I am prestudying the course material for Advenced Nitrox and the manual states that the IANTD tables are Bühlmann based refined using EAD. I ran some of the tables through V-Planner and founds out that they match ZH-L16B with GF set to 75/75 pretty well.
In the manual the last pages are titled Advanced Recreational Trimix, probably they were put there to whet the student's appetite for more but the text leads to my question:

IANTD Advanced Recreational Trimix tables are based on the VPM algorithm.

Does anyone have the insight as to why IANTD uses Bühlmann tables for decompression diving on air and nitrox but VPM tables on trimix?

 

[Searcaigh]

Started the IANTD Advanced Trimix course two days ago with a friend of mine and we are using VPM-B for dive planning