Where Is Your GF?

[Dr Simon Mitchell]

So...accounting for the nitrox, that means the GF's were up from there on air. Extrapolating from Multi-Deco, I get Edge GFs of 80/90. Whaddya think, @Dr Simon Mitchell ?

Hi,

Well, it would probably be OK for a single air dive or two, but for technical diving the GFLo is a higher than I am comfortable recommending at this time, and the GFHi is definitely higher than I would recommend for any diving. Irrespective of what you think of deeper stops, it is padding of the shallower stops, and particularly the last oxygen stop that is likely to reduce risk the most.

Simon M

 

[rsingler]

Hi,

Well, it would probably be OK for a single air dive or two, but for technical diving the GFLo is a higher than I am comfortable recommending at this time, and the GFHi is definitely higher than I would recommend for any diving. Irrespective of what you think of deeper stops, it is padding of the shallower stops, and particularly the last oxygen stop that is likely to reduce risk the most.

Simon M

Oh, yeah! Wasn't advocating it by any means. Thank goodness I was just an occasional diver back when I used my Edge. Didn't get bent.
Nah, I was just asking if that seemed like a reasonable guess for the Edge's inherent GF's, based on what @RyanT told us.

 

[RyanT]

Nah, I was just asking if that seemed like a reasonable guess for the Edge's inherent GF's,

I got that!

And indeed, those GFs are way higher than I'd ever consider diving now. The Edge still has a special place in my heart and I'll always love it's graphical representation of tissue loading. But alas, it had to be retired.

 

[rsingler]

I got that!

And indeed, those GFs are way higher than I'd ever consider diving now. The Edge still has a special place in my heart and I'll always love it's graphical representation of tissue loading. But alas, it had to be retired.

To me, the interesting part is that you were bent doing recreational repetitive dives with the Edge. Did I read that right?
Notwithstanding that it may have tried to limit its recommendations to "2 dives a day", the notion that diving 80/90 WITHIN NDL's can bend you, not to mention 100/100, just lends more credence to my desire to dive a Shearwater to xx/xx (pick your poison), rather than relying on anyone's proprietary algorithm, especially on the DSAT side, for repetitive dives, even short of deco.

 

[100days-a-year]

To me, the interesting part is that you were bent doing recreational repetitive dives with the Edge. Did I read that right?
Notwithstanding that it may have tried to limit its recommendations to "2 dives a day", the notion that diving 80/90 WITHIN NDL's can bend you, not to mention 100/100, just lends more credence to my desire to dive a Shearwater to xx/xx (pick your poison), rather than relying on anyone's proprietary algorithm, especially on the DSAT side, for repetitive dives, even short of deco.

I have seen a couple divers bent within NDLs on dive 2 of the day without any ascent rate violations and guys do 40+ ( dives outside NDL ) within a weeks time on an EDGE regularly and not have any issues.That is what really started highlighting the relative unpredictability of DCS to me.We can choose to move in a safer direction but some risk will always be there.I agree I'd rather know which poison I'm drinking rather than trusting a proprietary one.

I respect all the body of work done to better understand DCS,but the natural variability of susceptibility between individual divers and even on the same divers at different times or situations make cut and dried claims seem difficult to objectively quantify to me.

 

[RyanT]

@rsingler, that was 1993, and I'm going on memory here, but my profiles were something like:
Dive 1: 125' for 18 min on the bottom
Dive 2: 135' for 16 min on the bottom
Dive 3: 125' for 18 min on the bottom
Dive 4: 90' for for 20 min on the bottom

Each surface interval was 1 to 1.5 hours. All dives on air. The Edge gave me some light deco on the first three dives (maybe 6-8 minutes). Definitely beyond the NDL limits for the first three dives.

 

[Alexandros]

GUE SOPs still suggests 20/85 in DecoPlanner. Hm...

edit: at the same time they give a red warning: "anything below the 21m stop is a slower ascent. There are no “deep stops” – just a controlled ascent!"

 

[Dsix36]

I began with 10/100 with my first GF experience and quickly learned that it sucked in both numbers. The first stop was too deep and I usually had niggles in my knee after rinsing gear and trying to relax.

Next was 30/70 as this was a reasonable "safe" place to begin when I got my first Shearwater.

In slow and methodical increments and a lot of diving before changing, I worked towards 60/90. I did a lot of diving with this and many were below 400'and one to 500'. I did a get pretty bad shoulder pain after a 300' dive with 9 hours of deco one time though.

60/90 on a dive below 600' got me a serious spinal DCS hit that I am still recovering from. I will be rethinking this GF for future deep or long dives.

 

[broncobowsher]

I'm just running the Shearwater 30/70 default. Nothing aggressive. Diving recreationally I'll bump into a minute of deco when others don't. Doing light deco dives (less than half hour deco obligation) I match pretty close to others who are older and dive conservatively. No one has been bent. Don't see it as a race to get out of the water sooner. If you need out sooner, you shouldn't have gone as deep or stayed as long (poor planning).

Now take that from someone who does light deco. I'm not doing 600' dives.

 

[Billy Northrup]

Well it depends. Environment, familiarity and the lay of the land (Example: tied in at 65 feet is a good place to gather up and switch). GF 40/80 works and I tend to heavily pad the last 30 feet, taking notes, cleaning up and I might as well suck the tanks down I gotta get'm filled anyways. When I get into the deco phase I stop hustling and chill.