Question about surface gradient factor

[Aerobics111]

Per my understanding, surface GF is your GF if you flash to the surface. So does this mean that when I have a surface GF of 60% during my dive and then suffer an uncontrolled ascent accident, the risk of getting DCS is comparable to someone who ascend to the surface in a slow and controlled manner but finishing with a GF of 60%?

Almost all my dives never have a surface GF higher than 80% at any point. Does this mean that the risk after a rapid ascent accident is low or this number gives a false sense of security?

 

[davehicks]

No, that is not what it means. A rapid ascent to the surface has dangers and risks all its own regardless of your SurGF. Embolism, bubble formation, etc are very serious risks. SurGF is just your current saturation status at a point in time and it gives you an idea of how much buffer you have from a required decompression stop.

You always need to go slow on ascent, as much as is possible and reasonable.

 

[admikar]

Per my understanding, surface GF is your GF if you flash to the surface. So does this mean that when I have a surface GF of 60% during my dive and then suffer an uncontrolled ascent accident, the risk of getting DCS is comparable to someone who ascend to the surface in a slow and controlled manner but finishing with a GF of 60%?

Almost all my dives never have a surface GF higher than 80% at any point. Does this mean that the risk after a rapid ascent accident is low or this number gives a false sense of security?

Speaking of SurfGF only, yes, you are correct.
Now, this being said, I don't know if there is any research done about rapid ascents and micro bubbles effect.

 

[davehicks]

Speaking of SurfGF only, yes, you are correct.
Now, this being said, I don't know if there is any research done about rapid ascents and micro bubbles effect.

Please don't encourage reckless behavior with incorrect information. SurGF was not intended to make divers think they can safely rocket to the surface! Please don't split hairs on this. There is no lack of research about embolisms or bubble formation vs ascent rate.

example: https://www.researchgate.net/public...ulating_Venous_Bubbles_in_Recreational_Diving

 

[Lorenzoid]

Just to add a nitpick, it's my understanding that SurfGF is a purely theoretical number representing what would be your GF if you could surface instantly, which you can't; even an uncontrolled ascent takes some time.

I like @davehicks description: SurfGF "gives you an idea of how much buffer you have from a required decompression stop."

 

[LFMarm]

In addition to the safety concerns raised above on fast ascents, you should notice that SurfGF is calculated assuming a safe ascent rate. If you storm to the surface, you will get there with a higher GF99 than that predicted by SurfGF

 

[Sevenrider860]

In addition to the safety concerns raised above on fast ascents, you should notice that SurfGF is calculated assuming a safe ascent rate.

That is not correct. There is no calculated ascent rate in the SurfGF value. It is exactly as described in the manual..."The surfacing gradient factor expected if the diver instantaneously surfaced."

 

[davehicks]

That is not correct. There is no calculated ascent rate in the SurfGF value. It is exactly as described in the manual..."The surfacing gradient factor expected if the diver instantaneously surfaced."

Yep, that's what it says. But please avoid teleporting to the surface for safety reasons.

 

[Wants2divemore]

Shearwater's exact quote on their blog explaining SurfGF when asked this question about teleportation was "We’re good – but we haven’t figured out how to teleport (yet!)"

Got to love when a company has a sense of humor.

 

[harvalen]

When they start selling teleportation devices that can handle being submerged to reasonable depths, let's hope there is a good bundle with a pressure chamber. Then you just set it to the correct pressure, teleport into it and have a nice slow dry deco. Could load it up with some nice snacks and so too.