Matching GF between main and backup computers?

[mje113]

I dive with a Perdix 2 (main) and an Apple Watch Ultra (backup, I really like the compass), and liked the fact that they both use the same algorithm. I just noticed that their "default" Gradient Factor settings aren't the same:

Perdix 2 "med" conservatism:
40/85

AWU "default" conservatism:
70/85

I feel like these should match, but I'm really not sure which to chose as I find GF a bit of a confusing topic.

 

[steinbil]

As long as you don't go into deco, they're identical. The first number (GFlo) will determine the depth of the first deco stop. A lower number, like 20 will give you deeper deco stops (also called deep stops) which is based on outdated science and has fallen out of favour.

 

[iliketopetsharks]

As long as the GF High stays the same, your NDL won't be affected, so it doesn't really matter. But would probably still be a good idea to match the GFs.

 

[JoeTPhilly]

I dive with a Perdix 2 (main) and an Apple Watch Ultra (backup, I really like the compass), and liked the fact that they both use the same algorithm. I just noticed that their "default" Gradient Factor settings aren't the same:

Perdix 2 "med" conservatism:
40/85

AWU "default" conservatism:
70/85

I feel like these should match, but I'm really not sure which to chose as I find GF a bit of a confusing topic.

If I recall correctly your GUE Fundamentals is coming up. GUE default gradient factors are 20/85 so maybe set both to that setting.

 

[grantmac]

Can set the GF to whatever you want on the Perdix.

 

[steinbil]

If I recall correctly your GUE Fundamentals is coming up. GUE default gradient factors are 20/85 so maybe set both to that setting.

There is no deco in GUE Fundamentals, so the GFlo won't apply. Actually the GFhi probably also won't come into play as (1) it's all about doing skills in shallow water, and (2) you learn to dive with a bottom timer/gauge mode.

As far as I know, 20/85 is only used by GUE for TRAINING PURPOSES, as it gives more stops, and GUE teaches to be a thinking diver and to keep up with current research. I don't know any GUE divers that dive 20/85.

 

[JoeTPhilly]

There is no deco in GUE Fundamentals, so the GFlo won't apply. Actually the GFhi probably also won't come into play as (1) it's all about doing skills in shallow water, and (2) you learn to dive with a bottom timer/gauge mode.

As far as I know, 20/85 is only used by GUE for TRAINING PURPOSES, as it gives more stops, and GUE teaches to be a thinking diver and to keep up with current research. I don't know any GUE divers that dive 20/85.

If going for GUE training, why not set it for the GUE default? It was suggested to me for the class to change the Shearwater default of 40/85 to 20/85. It wasn't a requirement to use gauge mode; just had to follow the minimum decompression limits and ascent profiles. I just used the timer function to do the stops and slides.

I think this is still current:

GUE Policies regarding gradient factors.

During the early 2000’s, GUE developed a reference standard based upon Buhlmann algorithms. The intent was to ensure divers reference profiles with the most successful history. From this base, consideration for team control and unity during ascent, as well as the potential utility of bubble control were considered. Balancing these factors resulted in a gradient factor of 20/85. These settings will not only result in deeper stops but will also account for these stops with additional decompression time.

Current research challenges the value of deep stops, suggesting they may be less efficient. GUE has been slow to adjust parameters for dives conducted during training because the relatively short profiles of students and their need to gain proficiency with a controlled ascent speaks against the value of faster ascents and/or shorter total decompression time. Balancing the experience in our community, while considering the most useful priorities for students, supports a deeper gradient than might be otherwise encouraged by developing research.

GUE protocols maintain a 20/85 reference gradient for training dives where the priority is ascent training and team refinement and where a slight increase in additional decompression time is not problematic. As divers gain experience. they are free to adjust gradients in a way that is suitable to the team while considering personal experience, team preference, mission objectives, and evolving research.

edit: added GUE policy

 

[Lorenzoid]

If going for GUE training, why not set it for the GUE default? It was suggested to me for the class to change the Shearwater default of 40/85 to 20/85. It wasn't requirement to use gauge mode; just had to follow the minimum decompression limits and ascent profiles. I just used the timer function to do the stops and slides.

It's not a requirement to use gauge mode in Fundies, but I found Fundies to be an opportunity to see how I could dive knowing just depth and time (which one could do in either gauge mode or computer mode). Post-Fundies, I went back to using my computer to track NDLs like pretty much everyone else. But it was interesting in class to reflect back on tables and learn the rule-of-thumb "rule of 130." Fundies is a diver's opportunity to expose themselves to new ways of looking at things.

Anyway, as others have said, since GFlow doesn't make any difference in no-deco, er, I mean "minimum deco" diving (as GUE calls it), during Fundies class the computer won't behave any differently whether set to 40/85 or 20/85 or XX/85. For that matter, since students doing skills in 20-30 feet of water never get anywhere close to NDL, whether GFhi is set to 85 or 80 or 75 doesn't really matter, either.

 

[JoeTPhilly]

It's not a requirement to use gauge mode in Fundies, but I found Fundies to be an opportunity to see how I could dive knowing just depth and time (which one could do in either gauge mode or computer mode). Post-Fundies, I went back to using my computer to track NDLs like pretty much everyone else. But it was interesting in class to reflect back on tables and learn the rule-of-thumb "rule of 130." Fundies is a diver's opportunity to expose themselves to new ways of looking at things.

Anyway, as others have said, since GFlow doesn't make any difference in no-deco, er, I mean "minimum deco" diving (as GUE calls it), during Fundies class the computer won't behave any differently whether set to 40/85 or 20/85 or XX/85. For that matter, since students doing skills in 20-30 feet of water never get anywhere close to NDL, whether GFhi is set to 85 or 80 or 75 doesn't really matter, either.

Yes, it was nice looking at it differently. I kept it in computer mode but was just looking at depth and time. However, it was nice to have the computer information as a comparison. For example, during time outside of class we planned a dive to a 100 feet; teammate was just using a bottom timer and I had my computer. It was planned for GUE MDL 30 minutes at 100 feet. My computer reflected a deco obligation since NDL the computer calculated was exceeded. It was good to see the difference between the two.

Also, although a lot of the skills are done in 20 feet of water; propulsion and drills. We did a lot of ascent training in somewhat deeper water; usually 60-70 feet. Just want to let the OP know everything won't be at 20 feet.

 

[steinbil]

If going for GUE training, why not set it for the GUE default? It was suggested to me for the class to change the Shearwater default of 40/85 to 20/85. It wasn't requirement to use gauge mode; just had to follow the minimum decompression limits and ascent profiles. I just used the timer function to do the stops and slides.

The instructor suggested this for your Fundies class? Did you take fundies to be able to take Tech 1? Maybe it was in preparation for that? My instructor didn't even mention GFs in my class.

Edit:
I see your edit added JJs explanation of why GUE uses 20/85 for training, that was the policy I was referring to.