forum.heinrichsweikamp.com

I dived yesterday with 2N and xDeep Black EANx. In Black conservatism was set to level 3 which reflects 65/20 and OSTC 2N set to 70/30. The NDL in OSTC was shorter and the difference was sometimes arround 10min. The settings in OSTC were less conservative, so why shorter times? Both are using ZH-L16+GF.

Because the gradient factors were set different. If they were the same then NDL and deco obligation would have likely been similar.

This is exactly what gradient factors do. They fine tune the ZH-L16 algorithm

Differences between different computer brands (Even if they are set "identical" and use the "same" model) are inexplicable unless we can compare the deco code.

Our's is here: https://bitbucket.org/heinrichsweikamp/ ... at=default ...

Regards,
Matthias

I'm no software designer, so I won't be able to check anything, even if I tried to reverse engineer the balck's code. So there's no way for me to compare them...
Mind this, I'm not indicating that there's anything wrong with both computers...

jb2cool, less conservative - longer NDL? More conservative - shorter NDL. Black was more conservative - 65/20 but shown more NDL than less conservative OSTC 70/30. As I said, the difference was sometimes around 10 minutes.

Sorry, I thought you were saying the OSTC was showing shorter deco, not less NDL remaining.

They were both set to the same gas weren't they?

Yes they were, doublechecked before the dive.

There are many factors affecting decompression calculation even with the same decompression model, for the start

- OSTC calculates your deco like you were 1m deeper (XDeep - I do not know)
- respiratory quotient used to calculate alveolar partial pressure (OSTC - ppWater = 0.0627; XDeep - no information)
- how NDL is calculated, i.e. is ascent to the surface included in desaturation calculations and at what speed? (OSTC - yes, 10m/min; XDeep - no information)
- bugs

And there can be more factors, I can imagine.

nodekh, IMHO your original question should be sent to XDeep, hard to guess what inside a black box (pun intended ).

wrobell Wrote:
-------------------------------------------------------
> - OSTC calculates your deco like you were 1m
> deeper

This is the first time I heard this.

jb2cool Wrote:
-------------------------------------------------------
> wrobell Wrote:
> --------------------------------------------------
> -----
> > - OSTC calculates your deco like you were 1m
> > deeper
>
> This is the first time I heard this.

CF-16

I think that if CF-16 is set to 1, the deco shown as been required is worked out as if you are doing it one metre deeper than the depth it should be done at. That is, it assumes that you will do your 12 m stop at 13 m, 9 m at 10 m etc. It does not calculate your depth one metre deeper during the dive than reality.

I am sure someone will correct me if I am wrong.

Clownfish, you are right. I shall be more precise!