New deco planning tool

[David Carron]

The rationale that I adopted following Doolette is to do GF Low = GF High * 0.83 from the average of the bN and bHe factors.

ZH-L16C Parameters (bar minute units)

Comp.​

1​

2​

3​

4​

5​

6​

7​

8​

9​

10​

11​

12​

13​

14​

15​

16​

​

5.0​

8.0​

12.5​

18.5​

27.0​

38.3​

54.3​

77.0​

109.0​

146.0​

187.0​

239.0​

305.0​

390.0​

498.0​

635.0​

​

1.1696​

1.0​

0.8618​

0.7562​

0.62​

0.5043​

0.441​

0.4​

0.375​

0.35​

0.3295​

0.3065​

0.2835​

0.261​

0.248​

0.2327​

​

0.5578​

0.6514​

0.7222​

0.7825​

0.8126​

0.8434​

0.8693​

0.8910​

0.9092​

0.9222​

0.9319​

0.9403​

0.9477​

0.9544​

0.9602​

0.9653​

​

1.88​

3.02​

4.72​

6.99​

10.21​

14.48​

20.53​

29.11​

41.20​

55.19​

70.69​

90.34​

115.29​

147.42​

188.24​

240.03​

​

1.6189​

1.383​

1.1919​

1.0458​

0.922​

0.8205​

0.7305​

0.6502​

0.595​

0.5545​

0.5333​

0.5189​

0.5181​

0.5176​

0.5172​

0.5119​

​

0.4770​

0.5747​

0.6527​

0.7223​

0.7582​

0.7957​

0.8279​

0.8553​

0.8757​

0.8903​

0.8997​

0.9073​

0.9122​

0.9171​

0.9217​

0.9267​

What is your rationale for 80/70 on air? Genuinely curious.

I'm basically an 80/80 kind of guy. Dropping GFhi a little basically just adds a short loading-dependent safety stop at 3m without significantly impacting deeper stops

 

[bardass]

Thank!
Good news: the new version that I've just uploaded supports metric! You can use the easy button on the top right, or go to your profile (menu on the left, click on your user name and set the default system)

I've got the feedback of the GF slider. The reason why the scale moves but not the number is because by definition GFL always must be smaller that GFH. So if you move GFH the tool will prevent you from choosing a GFL that's higher that GFH - and that's why the slider changes the scale, but the number remains.

I am not aware of any definition that requires GF Low to be lower than GF High.
E. Baker does not mention this.

The rationale that I adopted following Doolette is to do GF Low = GF High * 0.83 from the average of the bN and bHe factors.

ZH-L16C Parameters (bar minute units)

Comp.​

1​

2​

3​

4​

5​

6​

7​

8​

9​

10​

11​

12​

13​

14​

15​

16​

​

5.0​

8.0​

12.5​

18.5​

27.0​

38.3​

54.3​

77.0​

109.0​

146.0​

187.0​

239.0​

305.0​

390.0​

498.0​

635.0​

​

1.1696​

1.0​

0.8618​

0.7562​

0.62​

0.5043​

0.441​

0.4​

0.375​

0.35​

0.3295​

0.3065​

0.2835​

0.261​

0.248​

0.2327​

​

0.5578​

0.6514​

0.7222​

0.7825​

0.8126​

0.8434​

0.8693​

0.8910​

0.9092​

0.9222​

0.9319​

0.9403​

0.9477​

0.9544​

0.9602​

0.9653​

​

1.88​

3.02​

4.72​

6.99​

10.21​

14.48​

20.53​

29.11​

41.20​

55.19​

70.69​

90.34​

115.29​

147.42​

188.24​

240.03​

​

1.6189​

1.383​

1.1919​

1.0458​

0.922​

0.8205​

0.7305​

0.6502​

0.595​

0.5545​

0.5333​

0.5189​

0.5181​

0.5176​

0.5172​

0.5119​

​

0.4770​

0.5747​

0.6527​

0.7223​

0.7582​

0.7957​

0.8279​

0.8553​

0.8757​

0.8903​

0.8997​

0.9073​

0.9122​

0.9171​

0.9217​

0.9267​

What is your rationale for 80/70 on air? Genuinely curious.

Doolette clearly explained that his choice of 0.83 is a personal preference and that he does not impose it on anyone.

 

[LFMarm]

Doolette clearly explained that his choice of 0.83 is a personal preference and that he does not impose it on anyone.

My personal choice is to follow the personal choice of a world class expert in decompression.

 

[bardass]

for sure
but it doesn't mean that GF Low must be smaller than GF High "by definition"

 

[LFMarm]

for sure
but it doesn't mean that GF Low must be smaller than GF High "by definition"

Agree. I was just asking for the rationale and provided the one I use (which is for sure not the only one but the one that made the most sense to me).

 

[bardass]

UPDATES on Version 5.3.0
- now supports metric
- some minor display bugs were fixed
- added gas consumption estimations (bottom of the screen)

A quick comment on the requirement for internet: the tool was mostly developed for training purposes. That's the reason for the tissue animation, the what if..? cases, etc. I clearly understand that some people may do planning on the boat or while at the dive site and I respect that. In my cases (living in south FL) internet availability is not a real problem. Again, MultiDeco, Baltic (and some other tools) are great resources (which I will continue using), but I see there's value on a graphical tool that will allow you to have that "day before diving" analysis done (which I do a lot).

More features will come live soon (set last stop to 6m/20ft, save favorites gases, save dive profiles, export to pdf, etc)

Happy diving.

doesn't work for me, no calculation when clicking

 

[pstrika]

doesn't work for me, no calculation when clicking

Thanks. I will take a look at why is not getting back results.

 

[pstrika]

for sure
but it doesn't mean that GF Low must be smaller than GF High "by definition"

You put me to think (a lot actually about this).

I concluded that GF Low has to be lower that GF High - not because the math doesn't work but because it may not make sense to what the decompression tries to achieve.

I had a little conversation with ChatGPT and this was its conclusion too:
If GF low > GF high, it leads to a logical contradiction: you’re allowing more supersaturation at depth than near the surface—which violates safe decompression logic. Most dive software will either block it or behave erratically.

Still, great question to debate!

 

[OTF]

Wouldn't that just push your first stops shallower and shorter, and make your later stops much longer? Running a conservative inverted GF like 60/40 would make for long deco times and isn't practical but it's not necessarily bad. It's pretty much what your profile might look like if you did a deep wall dive, ascended somewhat aggressively up the reef, and spent an extra extended time hanging out in the shallows. A fairly common and safe profile to dive. Multideco didn't let me try setting the GFs like that though, ha.

 

[inquis]

If GF low > GF high, it leads to a logical contradiction: you’re allowing more supersaturation at depth than near the surface—which violates safe decompression logic.

Sorry to break it to you, but ChatGPT doesn't realize that greater supersaturation at depth is an intentional characteristic of ZHL-16. (Even GFs like 70/80 yields greater supersaturation at depth than near the surface.)

The fact is that something like 80/70 (yes, GFLow greater than GFHigh) still has 20% less supersaturation in the fast tissues than Buhlmann felt was required to avoid DCS. The amount of margin will always be a personal call.