GUE Deco planner 4 & recommended Gradient factors for air diving

[TecRec50]

Hi guys,

I was highly surprised by a recent GUE video about their Deco planner and by their recommendations for GF :
- The updated (2022) GUE deco planner 4 still gives the possibility to plan deco with the VPM bubble model. I thought that after the NEDU study dated 2011, no-one would ever use a bubble model to plan a serious deco, even if diving trimix ... What do you guys think about VPM ?
- With Bühlmann, the GF presets are still 20/85 ! Even worse than the Shearwater presets ... In this video, a deep air diving is completed with GF 20/85 ... What do you guys think about GF 20/85 (Bühlmann) for air diving and the implied deep stops ?
Kind bubbles & regards

 

[L13]

- With Bühlmann, the GF presets are still 20/85 ! Even worse than the Shearwater presets ... In this video, a deep air diving is completed with GF 20/85 ... What do you guys think about GF 20/85 (Bühlmann) for air diving and the implied deep stops ?

GF-Low of 20 is always a bad idea (unless maybe if GF-high is around 25, and who is going to be that stupid conservative).

 

[CAPTAIN SINBAD]

As someone who favored deep stops, I have changed my own views on it ever since UTD did its Spisni study and Dr. Simon Mitchell gave his own views on it. Bulk of scientific evidence is against these deeper stops. Jarod Jablonski still thinks otherwise and posted his own views on deep stops. I do not see any following of deep stops other than devout GUE traditionalists. Interestingly, UTD who were most insistent on these super deep stops have changed their ratio deco to 35/85 and are moving even shallower.

 

[steinbil]

I was highly surprised by a recent GUE video about their Deco planner and by their recommendations for GF :
- The updated (2022) GUE deco planner 4 still gives the possibility to plan deco with the VPM bubble model. I thought that after the NEDU study dated 2011, no-one would ever use a bubble model to plan a serious deco, even if diving trimix ... What do you guys think about VPM ?

In my experience GUE is very open about how uncertain DCS science is, and encourages their divers to dive conservatively and do their own research, as well as gradually extending your comfort zone and adapting your dive profiles based on your own experience in the water. They have very strict requirements and standards for classes, and also recommended standards for GUE diving based on ideas of team standardization and using the right tool for the right job. That said, I don't personally know any GUE diver using VPM.

- With Bühlmann, the GF presets are still 20/85 ! Even worse than the Shearwater presets ... In this video, a deep air diving is completed with GF 20/85 ... What do you guys think about GF 20/85 (Bühlmann) for air diving and the implied deep stops ?

First off, air is not a recommended gas in GUE. Especially for deeper dives. On the subject of the GF20/85, here's a quote from Jarrod Jablonski about the use of this gradient factor in planning and training:

GUE protocols maintain a 20/85 reference gradient for training dives where the priority is ascent training and team refinement and where a slight increase in additional decompression time is not problematic. As divers gain experience. they are free to adjust gradients in a way that is suitable to the team while considering personal experience, team preference, mission objectives, and evolving research.

Again, most GUE divers I know dive with different gradient factors, de-emphasizing deep stops. 40-50/70-85 is quite common among the divers I've talked to.

Bulk of scientific evidence is against these deeper stops. Jarod Jablonski still thinks otherwise and posted his own views on deep stops. I do not see any following of deep stops other than devout GUE traditionalists.

See my replies above. You can read more about Jarrods take on decompression science here (from 2019).

 

[CAPTAIN SINBAD]

Dr. Mitchell added his perspective to that and it is here:

Gradient factors - deep stops thread in DIR forum

Hello I find that I cannot post in relevant thread in the DIR forum, so I thought I might put a post here. I don't want this to turn into a deep stops debate. We have been through enough of that already. I have read the article by Jarrod Jablonski linked to in that thread and I just wanted to...

scubaboard.com

I think we all agree that decompression will require a deepest stop but where should that stop be, is the question. Gradient Factors of 20/85 are outside of what modern understanding would consider safer decompression. But, as you pointed out, if these GFs are being used for training purposes, just to add practice stops all the way up to the top, then the issue is more understandable.

 

[L13]

First off, air is not a recommended gas in GUE. Especially for deeper dives. On the subject of the GF20/85, here's a quote from Jarrod Jablonski about the use of this gradient factor in planning and training:

That kind of makes sense. While a higher GF-low will produce a safer dive with the same total time (by dropping GF-High to keep deco time the same), the difference is not usually large unless doing "big" dives. But by adding the other stops, you would add a lot of deco training/practice on "smaller" dives.