DSAT vs GF high 95, examples

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scubadada

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I have written previously about my experience diving DSAT and Buhlmann ZH-L16C with a GF high of 95. I have an example of what I have previously reported. This dive is a first dive of the day on the Castor in Boynton Beach. It was relatively deep with a max depth of 107 feet and an avg depth of 73 feet. DSAT gave me a minimum NDL of 6 minutes. A GF high of 95 on my Teric gave me 1 min of deco at 10 feet.

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This is a dive later in the week. It is the 4th dive of the day, following 3 moderately deep and long dives. This was a relatively shallow, reef, drift dive with a max depth of 60 ft and an average depth of 52 ft. DSAT gave me 5 min of deco at 10 feet. Buhlmann, GF high of 95 gave me a whopping NDL of 40 min. Personally, I find these results reasonably interesting. I have over 2,000 dives with DSAT, just under 900 with Buhlmann. I dive my more conservative computer for no stop diving. I clear one or both of my computers when I have a deco obligation. Now, with SurfGF, I surface with a GF of no higher than the low 80s.

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inquisit

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Does your log program let you override the dive computer's GF and show you the updated NDL/deco information? I'm wondering if you have a feel for what GFhigh might match up later in the day?
 
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scubadada

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Does your log program let you override the dive computer's GF and show you the updated NDL/deco information? I'm wondering if you have a feel for what GFhigh might match up later in the day?
Very interesting question, When I first started diving Buhlmann it was with a Dive Rite Nitek Q. My goal was to match DSAT. I would start off diving a GF high of 99 and would then decrease to 90. This was a pain in the ass and I just stayed at a GF high of 95 and dealt with it as above. That works out just fine, I know how the 2 computers are going to perform and am ready to deal with it. Overall, my strategy is on the more conservative side, especially with regard to my SurfGF.
 
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scubadada

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Hi @inquisit

I have my surfacing GF (from the Shearwater Cloud Desktop) for my last 178 dives, 59 +/- 11 (mean +/- std dev) with a range of 25-80. About 5% of my dives are light deco on one or both of my computers, many dives approach the NDL. I used to pad my deco dives with 3-5 min after clearing deco and followed the equivalent of a Shearwater adaptive safety stop for dives near NDL. Now, with SurfGF on my Teric, surfacing is without guesswork. Regardless of the SurfGF, I continue to do a 3 min safety stop after a no stop dive. My final ascent is generally over a minute. the GF bump on the final ascent is quite obvious on the graphs. Here is the same graph from the Castor with GF shown. the surfacing GF for this dive was 79.

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inquisit

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I do the final ascent very slowly as well, and it's nice to see GF99 behaving as a result.
 

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if you choose to dive with a GF-high of 95, you’re obviously accepting you’ve a higher risk of DCS. Your choice, but the current consensus is a more conservative GF-high of 80 or lower (cf Simon Mitchell et al)

The preceding three "deeper, longer" dives that day would have filled the slow compartments and would probably control the decompression schedule In the final dive. Probably affected the prev dive(s) too.
 
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scubadada

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if you choose to dive with a GF-high of 95, you’re obviously accepting you’ve a higher risk of DCS. Your choice, but the current consensus is a more conservative GF-high of 80 or lower (cf Simon Mitchell et al)

The preceding three "deeper, longer" dives that day would have filled the slow compartments and would probably control the decompression schedule In the final dive. Probably affected the prev dive(s) too.
I don't think you have followed, Pay more attention. I dive DSAT and GF high of 95 for the bottom time. I have not surfaced with a GF of over 80 since I have been able to follow Surf GF. Looks like I easily have more that twice your dives, under a very wide variety of environments.
 

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I don't think you have followed, Pay more attention. I dive DSAT and GF high of 95 for the bottom time. I have not surfaced with a GF of over 80 since I have been able to follow Surf GF. Looks like I easily have more that twice your dives, under a very wide variety of environments.
That’s me told then.

Why not just follow a standard Bulhmann + GF for every dive, say 50:80?

Mixing algorithms is frustrating as there’s always differences.
 
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scubadada

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That’s me told then.

Why not just follow a standard Bulhmann + GF for every dive, say 50:80?

Mixing algorithms is frustrating as there’s always differences.
I don't think you got it, Most of my diving is no stop, a minority of light deco. Why should I dive a tech std of 50/80? I actually dive 80/95. I have already explained how I reconcile the differences between DSAT and Buhlmann. If your diving is different, why should you care, What am I doing wrong? I surface with a GF no higher than 80. Almost all my diving is solo drift diving. Even if I dive with someone, their dive profile does not affect me. They ascend on my flag whenever they want to.
 

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I also dive on GF 45/ 95 for recreational diving where I am not going into deco. I also spend the last part of the dive quite shallow often around 5m as taking video and photo's on reefs. Surf GF never seems to be an issue when doing the last part of the dive at shallow depth.

Even on deep dives never been an issue with the GF or GF Surf

GF 45M DIVE.jpg
 
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