Gradient factors display

[Miguel R.]

Hi There

First of all, thank you for the brilliant work you have done with Subsurface. I use it to consolidate dive information from the days when I didn't own a dive computer, as well as from dives where I used rented equipment. Subsurface has enabled me to centralise all of my dive logs in one place and access them across multiple platforms with ease.

It's a fantastic piece of software and has become an invaluable part of my diving records. Well done, and thank you for all your hard work.

I have a small query regarding Gradient Factors.

I recently moved to a new dive computer, the Suunto Nautic, and have been embracing the Bühlmann decompression algorithm. I must say, i love it! :-)

I understand that Suunto can be somewhat protective of its intellectual property and has not released a suitable API for full Subsurface support. That is absolutely fine—I have managed to import most of the relevant information via FIT files, and I actually enjoy reviewing and analysing the dive data afterwards.

One thing I have noticed, however, is that the Gradient Factors displayed in the dive profile window do not appear to correspond to the values that were used on the dive computer. This does not seem to be related specifically to the Suunto Nautic. In fact, I cannot find anywhere within Subsurface to enter or edit Gradient Factors on a per-dive basis. As things stand, the profile header is the only place where I can see Gradient Factors displayed.

After some investigation, I found that these values can be modified in the Technical Settings section. However, changing them there appears to apply them globally across all dives rather than allowing different values to be assigned to individual dives.

Would it be possible to make these figures manually editable on a per-dive basis? It would be very useful for those of us who use multiple computers, experiment with different Gradient Factor settings, or simply wish to keep an accurate record of the parameters that were used for a particular dive.

Thank you for your time, and once again, thank you for all the work that goes into Subsurface.

[Robert C. Helling]

This request has reached us multiple tomes. But so far we have decided against it. If that information is downloaded, Subsurface displays the ceiling computed by the dive computer during the dive. This of course is per dive and is computed by whatever algorithm the dive computer uses. Here Subsurface is agnostic. Some dive computer report Gradient factors that they have used and you find those in the extra information tab,

On the other hand, Subsurface computes its own ceiling that displays what depths are considered safe by some algorithm with some settings. This is a a tool to evaluate how close a given dive comes to the limits that you set yourself. And that is about the actual depth profile you dived and not about the computer you used. And that, we think, should be a global setting for all your dives (which of course you can adjust as much as you want). But when you copare different dives, you want to compare them to one coherent standard and thus the parameters of the deco model should not vary between dives. 

I understand you can have different preferences but we decided these make most sense from our perspective.

Best

Robert

[Miguel R.]

Hi Robert

Many thanks for your kind and prompt reply. As I mentioned, I have a Nautic and I normally import the dives into Subsurface via the FIT file format way. Subsurface does pick up the gradient factors used by the computer (as the image seems to show). But i dont think it calculates the ceiling. Again, not a problem. ;-)

Thanks

[Alon Dotan]

Try to use the json loader for the nautic, you will get more details 

--
You received this message because you are subscribed to the Google Groups "Subsurface Divelog" group.
To unsubscribe from this group and stop receiving emails from it, send an email to subsurface-dive...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/subsurface-divelog/3856f0cf-e3ee-4856-bd72-2248b3011c13n%40googlegroups.com.

[Miguel R.]

Hello again.

I have some time on my hands, so I am looking at this JSON vs FIT import. I found some very interesting things....;-) I am running the latest beta (6.0.5668), and then the following happens:

I first import the FIT file, and I get the following info

I get the correct GF and GPS location, but this seems to be purely indicative data, as Subsurface does not calculate the ceiling...

On the same file, I import the EXACT same dive but this time as a JSON file, and I get the following

 With a different set of data, Subsurface calculates the ceiling according to the settings in Technical dive. The interesting thing that happens is that if I now select the previous import, it seems that the correct GF 45/90 ceiling appears calculated on the dive!!!

with the JSON file i also get the correct start and end pressure btw.

so the next step would be to MERGE the dives and see what happens ;)

The JSON "wins" the profile retains the GF 35/70 ceiling.

only interesting thing is that I get the both pressures infop from the FIT and JSON files combined, well, sort of ;-)

feels to me that the moving forward workflow when importing from Suunto to Subsurface is to import both formats, check if the ceiling corresponds to the correct GF's and then delete the JSON file. 

I'll keep tinkering with formats... :-)

Thanks

[Alon Dotan]

Something is very strange in your examples...
Let's start with the fact that SS doesn't recognize the model of the computer for the imported dive...
You should see the dive model is Suunto Nautic...
If possible please delete all the dives you imported with FIT / JSON from the nautic and import ONLY the json format, lets see the behavior 

To view this discussion visit https://groups.google.com/d/msgid/subsurface-divelog/3fbe6fab-83db-4678-906f-27f8dcd7e3bfn%40googlegroups.com.

[Miguel R.]

Hi Alon

That is correct. Importing the dive as a JSON file shows as if it was imported from the nautic itself, and importing as a FIT file shows as a FIT file import. Both imports show different info, as you can see from the images below

I actually prefer the FIT file as it brings in the GF numbers as well as the GPS location

Thanks

[Alon Dotan]

For the GPS location its an issue Im currently working on fixing, Ill TAL on the GF factors also

To view this discussion visit https://groups.google.com/d/msgid/subsurface-divelog/f8ecfa9d-5c50-4bf8-9b16-759b938645fen%40googlegroups.com.

[Miguel R.]

fantastic news!!

Many thanks for all the work done

[tormento]

It’s a bit hard to have a ceiling with a 45-minute dive at 20 meters.

[Miguel R.]

Thanks for your email. You are probably right…

I was expecting a very very shallow one of maybe 1-2 meters 

When subsurface gets the right gf numbers it shows a very thin green line which is what I was expecting. 

Maybe I should try with a deeper dive

Thanks 

Sent from my iPhone

On 11 Aug 2026, at 20:12, tormento <tur...@gmail.com> wrote:



<NAUTIC FIT EXPORT.png>

--
You received this message because you are subscribed to a topic in the Google Groups "Subsurface Divelog" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/subsurface-divelog/7ovyHjmuOQA/unsubscribe.
To unsubscribe from this group and all its topics, send an email to subsurface-dive...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/subsurface-divelog/CAMmfe5E6rU3o4LHHY4_9vfM8oM_oxDW21R3EFXTJKvUgX0c08A%40mail.gmail.com.

[Jason Bramwell]

The green line is the ceiling calculated by Subsurface itself, this has no bearing on what settings the dive computer itself used. There is a setting within Subsurface to show the dive computer reported ceiling, this shows exactly the ceiling that the dive computer showed during the dive and this uses the dive computer settings.

Jason

Sent from my iPhone

On 11 Aug 2026, at 21:15, Miguel R. <mig...@gmail.com> wrote:



You received this message because you are subscribed to the Google Groups "Subsurface Divelog" group.

To unsubscribe from this group and stop receiving emails from it, send an email to subsurface-dive...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/subsurface-divelog/FFA31593-FEED-4C8E-A26B-0631DDE75FD6%40gmail.com.

[Michael Keller]

Hi Miguel.

Since version 6.0.5647 (available on https://subsurface-divelog.org/latest-release/), Subsurface actually supports importing sets of .fit and JSON files for the Suunto Nautic, automatically combining the information for both. This should resolve most of the issues discussed in this thread:

https://github.com/subsurface/subsurface/pull/4855

Ngā mihi

  Michael Keller

--

GCS$/CC/E/IT d- s+ a C++ UL+++/S++ P L++ E-
W++ N o? K? w O(++) M-- V+ PS+ PE+ Y? PGP+ t
5? X R tv b++ DI++ D++ G e+++ h---- r+++ y+++