Question calculating NDL is difficult

[int]

Where did you get shearwater values? Did match water density ? I recall shearwater uses European definition

As far as I know, the density of water is needed to calculate the current depth of water.
But after diving with shear water, I pull out the log. Then, depending on the density of the water, the water depth data will come out, and we just used it.

 

[int]

Given the imprecision of any current decompression algorithm to predict a divers risk for DCS, your exercise is like measuring with a micrometer, marking with chalk, and cutting with an axe

Yes, you're right.
But to ensure minimum stability, I try to make it as similar as possible.

 

[inquis]

fortunely, the values are very similar to mine. Unfortunately, there is also a difference from shear water

FYI, Shearwater uses the current altitude/atmospheric pressure, which may differ from your assumption. I ensure these things match when comparing deco plans from different planners:

• Altitude (surface pressure)
• Ascent/Descent rates
• Salinity
• Gradient Factors
• Previous dive loading (or lack thereof)

 

[int]

FYI, Shearwater uses the current altitude/atmospheric pressure, which may differ from your assumption. I ensure these things match when comparing deco plans from different planners:

• Altitude (surface pressure)
• Ascent/Descent rates
• Salinity
• Gradient Factors
• Previous dive loading (or lack thereof)

I also checked the log and it seems that my computer does not use water vapor.
There is also a setting of the gf value, the value of gradient high affects ndl, and the surface pressure is 0.79 N2 at 021ead.
As the result of the second dive changes due to the previous dive, it's right to go in, and the salinity is the difference in depth, so I'm going to use it as shown in the log for now.

However, the Ascent/Descent rates were set to 10m per minute as Baker mentioned.
The Ascent/Descent rates I set up are used to calculate the pressure value of the tissue, but there was actually no significant difference.

We are currently trying to change the existing unit from atm to bar.

 

[John C. Ratliff]

There is only one reason to use water vapor in the calculation, and that is to extend the bottom time. Think about it, if your computer doesn’t use water vapor, it has a built-in safety factor. The reason to use water vapor is to decrease the amount of nitrogen in the lungs, which will increase the time before saturation with nitrogen occurs. So to my way of thinking, use of water vapor in a calculation is a means of maximizing bottom time, and thereby “pushing the envelope” as aviators say.

SeaRat

 

[int]

There is only one reason to use water vapor in the calculation, and that is to extend the bottom time. Think about it, if your computer doesn’t use water vapor, it has a built-in safety factor. The reason to use water vapor is to decrease the amount of nitrogen in the lungs, which will increase the time before saturation with nitrogen occurs. So to my way of thinking, use of water vapor in a calculation is a means of maximizing bottom time, and thereby “pushing the envelope” as aviators say.

SeaRat

So this is the meaning of the results I saw.
I'm trying to be more conservative. After that, I will do more experiments and add more water vapor.

 

[Nick_Radov]

A number of years ago I was discussing a fatal diving accident on an attempted deco dive at an elevation of 16,000 feet/4,876 meters, and one of the people with whom I was discussing was a high altitude decompression specialist consulting with both NASA and the Pentagon (U2 flights).

I assume you're referring to Geoff Belter, who died in 2014 on a technical dive in Lake Sibinacocha in Peru. I remember hearing about that but never saw the details. Do you know if there was ever a real accident report published? There's a short article in Outside magazine but some parts don't make sense.

A High Case of the Bends

George Watson was on an exploratory scuba dive in a remote lake in the Peruvian Andes when everything that could go wrong suddenly did

www.outsideonline.com

To summarize my understanding of what he said, he believed that there were only about a half dozen people in the world with enough knowledge to plan such a dive, and he was one. Apparently the rules and procedures that apply to dive planning at more normal elevations go out the window when you are at such an elevation. He cited water vapor as an example of something that has to be treated differently there.

Nathalie Cabrol would presumably be one of those half dozen people. She holds the women's altitude diving record at 19,400 ft. Lex Fridman just did a fascinating interview with her where she talks about researching extremophile bacteria in high altitude lakes (although she didn't go into water vapor issues).

#348 – Nathalie Cabrol: Search for Alien Life | Lex Fridman Podcast

Nathalie Cabrol is an astrobiologist at the SETI Institute, directing the Carl Sagan Center for the Study of Life in the Universe. Please support this podcast by checking out our sponsors: – True Classic Tees: https://trueclassictees.com/lex and use code LEX to get 25% off – Shopify...

lexfridman.com

 

[inquis]

@Nick_Radov thanks so much for the links.

 

[inquis]

There is only one reason to use water vapor in the calculation, and that is to extend the bottom time.

I think the primary reason it's included is because it's more realistic to do so. When something is known to be true and trivial to implement, it seems silly to not include it (especially when there is already a method of increasing conservatism present).

 

[inquis]

We are currently trying to change the existing unit from atm to bar.

As the internal working unit of pressure, including tissue tension? IMO, it's much easier just to use meters (or feet) of seawater (or freshwater).