Rising GF99 after surfacing???

[scubadada]

...But I confess, I'm trying to learn the utility of having SurGF in the display, other than curiosity about how high it got during the dive...

Hi @rsingler

Good question.

Admittedly, I am a real nerd when it comes to collecting and analyzing data regarding my dives. I have paper logs and a spreadsheet for all 2343 dives I have done since 1997. My last 1900 dives are downloaded and I have a RMV for 1871 of those dives. I dived only DSAT until 2016, when I added a computer running Buhlmann ZH-L16C with GF. I added my Teric and the SW Cloud in 2019.

My diving is significantly less complicated than yours. The majority of my diving is no stop, only about 5% is light deco, generally less than 10 minutes. I really appreciate the extra information available from my Teric. SurfGF has ended the guesswork around padding the safety or deco stop. End surface GF confirms my more conservative goal.

So, why would I like SurfGF on the graph? For my dives, there is no graphic record regarding GF99 until it starts to rise on the ascent, peaking upon surfacing. The SurfGF data is available for the entire dive, I would like to be able to review it to get an idea of where I was earlier in the dive. This information would be complimentary to knowing your NDL or deco time.

Do I need SurfGF on the SW graph, no. Would I like to see it, sure, one more thing for me to analyze

 

[rsingler]

Good points, @scubadada .
I will confess, I too find the dedication of an entire graph line to GF99 useless until the end.
The occasional blips of GF99 above zero during a move to shallower water are mildly interesting, but otherwise of little utility.

You're right - it would be fun to parse the data.
I suspect it would reinforce what we already know intuitively - that things change rapidly during the deep portions of our dives (as well as right near the surface). It might give us more bang for the buck in reminding us of the consequences of minutes at depth. I'm going to go back to Subsurface and see what it's showing me. I'm guessing that the curve will be an inverse of my tank pressure curve: when my remaining gas pressure starts plummeting at depth, my SurGF is rising fast. But knowing where it maxed would be interesting.

Maybe I'll reexamine one of the Subsurface plots...
Thanks, @scubadada !

 

[scubadada]

Hi @rsingler

I don't use Subsurface, yet. Maybe I'll give it a try to be able to look at SurfGF until SW adds it to their graph.

One other thing I would like is the ability to enter cylinder specs to the gases summary so that it can calculate RMV. I would much rather see a graph of RMV rather than SAC, as it is cylinder independent.

I also give Shearwater credit for the improvements they have made in the Cloud. Now, if only I can get myself a perfect Teric

 

[rsingler]

Well, Shearwater is adamantly opposed to implementing RMV, due to the possibility of diver error (forgetting a tank switch). So that won't happen. But I hear you. I'm getting pretty good at mentally converting SAC's to RMV for my AL80 dive vacations.

And as for the Teric, I'm glad I stuck with a clunkier Perdix AI. Can't beat a simple AA cell, in a pinch.
Now, if only I could justify the cost of haptics and a Perdix 2. I'll definitely go that route when I go back CCR again in the spring. Petrel 3 I can justify on safety grounds - I get distracted easily.

Just for grins, I added the SurGF's from my dive to Devil's Throat in Cozumel in November, to the Shearwater graph. Note the sudden jump in GF99 as ascent started, while Sur GF continued at its usual 2-3% per minute decline.

 

[scubadada]

Well, Shearwater is adamantly opposed to implementing RMV, due to the possibility of diver error (forgetting a tank switch). So that won't happen. But I hear you. I'm getting pretty good at mentally converting SAC's to RMV for my AL80 dive vacations...

I communicated this request poorly. I did not mean entering the cylinder specifications directly into the computer and having it calculate RMV rather than SAC.

I meant having the ability to enter the cylinder specifications into the Gases summary in the Cloud and having the RMV calculated in the Cloud output. It might also be possible to use this to change the graph from SAC to RMV. Even my ancient Oceanic OceanLog allows one to choose a default cylinder or another one from a dropdown list and then calculate RMV from SAC.

As @rsingler pointed out, it is very easy to calculate RMV from SAC by multiplying by the tank factor.

As a matter of priority, I would much rather have SurfGF added to the Cloud graph rather than the addition of RMV. Maybe both

 

[batdiver_82]

hi again, did 3 dives after the latest update and my end-dive-gf matches the last shown surf-gf in subsurface by 0 to +1% now, which is good enough for me - I am happy now.