Gradient Factors For a Rookie

[boulderjohn]

I’m not sure I agree with the idea that gf low doesn’t matter.

If you manipulate your GF low to be low enough, you’ll get a stop where you otherwise wouldn’t have one.

I am talking about NDL diving, where the only stop you are expected to take is a safety stop.

 

[scubadada]

I’m not sure I agree with the idea that gf low doesn’t matter.

If you manipulate your GF low to be low enough, you’ll get a stop where you otherwise wouldn’t have one.

My understanding is that if you don't exceed GF high, you have no stops, regardless of GF low

 

[boulderjohn]

This idea of instant transportation to the surface has me confused. Does this mean like in a CESA scenario, OR, does the SurfGF assume a slow ascent (10m/min) and safety stop?

It does mean that it is what would happen if you went instantly to the surface, but that does not mean it is a recommendation. Your final ascent to the surface should always be done nice and s l o w l y.

 

[PfcAJ]

I am talking about NDL diving, where the only stop you are expected to take is a safety stop.

Yea but you can fiddle with the gradient factors and take a no-stop dive into a mandatory stop dive pretty easily.

Just playin with numbers, but if I plug in 100ft for 17mins, gf 95/95, I get no stops.

Same dive, but 20/95, and I get 1min stops starting at 50ft.

 

[Belzelbub]

This idea of instant transportation to the surface has me confused. Does this mean like in a CESA scenario, OR, does the SurfGF assume a slow ascent (10m/min) and safety stop?

Closer to CESA than a slow ascent. Think teleportation.

Also, I believe the number has some representation of residual nitrogen embedded in it, correct? So the lower the number, the more one is ready for the next dive?

SurfGF number would be the expected tissue loading in relation to the M value. So keeping that well below 100 would be what you are looking for. 70-75 would be good.

I normally do my safety stops, but use SurfGF to gauge safety if I need to skip it.

 

[inquis]

I believe DSAT is one of the few algorithms with published research and that the goal was specifically repetitive NDL dives. The clean times at least are similar to Buhlmann+GF x/95 if DSAT was working for you.

 

[scubadada]

Yea but you can fiddle with the gradient factors and take a no-stop dive into a mandatory stop dive pretty easily.

Just playin with numbers, but if I plug in 100ft for 17mins, gf 95/95, I get no stops.

Same dive, but 20/95, and I get 1min stops starting at 50ft.

On what planner do you get this? I don't see this on MultiDeco

 

[Alaskan Scuba Dude]

It's obvious Shearwater doesn't want you to get bent. Stay on the preset conservative factor. What's more important is the surface intervals.

 

[PfcAJ]

On what planner do you get this? I don't see this on MultiDeco

iDeco Pro

 

[inquis]

Just playin with numbers, but if I plug in 100ft for 17mins, gf 95/95, I get no stops.
Same dive, but 20/95, and I get 1min stops starting at 50ft.

Some planners will consider GFLow in their NDL calculations, but I don't believe that Shearwater does that. Anecdotally, the vast majority of the opinions I've seen regarding GF and NDL here on SB are on the "NDL is based on GFHigh" side of the fence.