Have ScubaBoard's SurfGF threads changed how you plan to dive?

[dmaziuk]

Yes, its on-gassing but then exponentially rises as I ascent.
But isn't it supposed to?

The question is whether the bigger numbers are scarier and smaller ones: "safer".

 

[rsingler]

Yes. The GF99 is what's displayed on Shearwater's graph. We haven't convinced them to add SurGF yet. So that's the closest correlate to what SurGF is predicting. Subsurface will show you SurGF, which matches what you'll see on your computer if you have SurGF enabled as an optional field.

In other words, if during your dive your SurGF goes to 150% (the GF99 you'd have if you surfaced immediately), it will decline during a safe ascent while your GF99 is simultaneously rising, such that at the end of a dive, the two will match. Similarly, the colored bar graph that blooms on ascent is as you said, GF99.
I am proposing that recreational divers use SurGF as a marker for their risk on ascent. But yes, I misspoke when I said above that SurGF blooms. I have edited my post. Thanks for pointing that out!

 

[rsingler]

Yes. I think bigger numbers are scarier. We may disagree.

 

[scubadada]

Here is a simple no stop dive. GF was about 30 at the safety stop, with a 1 min final ascent it increased to 77. I knew what to expect from my SurfGF. I use Surf GF to make sure I surface with a GF no higher than low-mid 80s. My average surfacing GF for all dives is right around 60. Most of my dives are no stop, many close to NDL I do light back gas deco on about 5% of my dives. The increase in the GF from the SS or deco stop to the surface was a real eye opener for me. I try to do my final ascent at 10 ft/min

 

[dmaziuk]

Yes. I think bigger numbers are scarier. We may disagree.

 

[EFX]

Here is a simple no stop dive. GF was about 30 at the safety stop, with a 1 min final ascent it increased to 77. I knew what to expect from my SurfGF. I use Surf GF to make sure I surface with a GF no higher than low-mid 80s. My average surfacing GF for all dives is right around 60. Most of my dives are no stop, many close to NDL I do light back gas deco on about 5% of my dives. The increase in the GF from the SS or deco stop to the surface was a real eye opener for me. I try to do my final ascent at 10 ft/min

View attachment 658108

What does the red line in the graph represent?

 

[scubadada]

What does the red line in the graph represent?

GF (GF99)

 

[scubadada]

I recently exchanged emails with Shearwater as I could not find an answer in the manual.

For no stop diving, you will not exceed the GF high with a direct ascent to the surface at the default ascent rate. Any safety stop will result in surfacing with a GF less than the GF high set

My question was: Assume that the GF high is set at 85. For no stop diving, does that mean the surfacing GF will be not higher than 85 with a direct ascent to the surface, or does it include the safety stop?.

Shearwater's response was: Safety stops are optional for no stop diving therefore it's not included. Another thing to take in consideration is ascent rate, default ascent rate for all our computers is 10m per minute/33f per minute.

 

[anchochile]

For those who are adopting slower ascents and especially longer safety stops in rec diving, I'm curious how that has been received when you're on a DM-led dive, e.g. from a day boat or liveaboard. Do you tell the DM ahead of time that you plan to do a longer safety stop? Are they generally ok with it or do you ever get pushback?

I already practice as-slow-as-I-can-manage ascents from SS to surface. I'm always the last diver to surface from the safety stop, and I'm thinking about adopting 5-minute safety stops, especially on longer/deeper dives, and am curious how that's gonna fly when I'm traveling & diving with operators rather than locally with my buddies.

 

[scubadada]

For those who are adopting slower ascents and especially longer safety stops in rec diving, I'm curious how that has been received when you're on a DM-led dive, e.g. from a day boat or liveaboard. Do you tell the DM ahead of time that you plan to do a longer safety stop? Are they generally ok with it or do you ever get pushback?

I already practice as-slow-as-I-can-manage ascents from SS to surface. I'm always the last diver to surface from the safety stop, and I'm thinking about adopting 5-minute safety stops, especially on longer/deeper dives, and am curious how that's gonna fly when I'm traveling & diving with operators rather than locally with my buddies.

Most guide led dives are not going to be pushing your GF high, probably, not even close. Non guided dives, pushing NDLs or doing light deco will be more challenging with regard to your surfacing GF. I have followed my surfacing GF over the last 122 dives. My average surfacing GF has only been 61, with a range of 43-80. I make my final ascent over a minute or more, the GF increases significantly over the final ascent. I assume you have access to SurfGF and GF99 to guide your choices. I used to do longer SS when very close to NDL and always padded my last deco stop, now, there is no guessing, I know exactly where I am.