comparing to actual surface is a hard thing todo cause it appears to imply things that may not be true as taken. 33 ft to surface is a 2 to 1 ratio. gf60 would be 1.6 atm or 20 ft. if you were looking at tissues at 100 ft or 4 atm and you were at 33 ft you would have a 2 to 1 ratio also so you gf60 should be a result of moving roughly 60% of the way from 33 to 100. or I guess 72 ft. if you were at 33 ft or 2 atm and you had a gf99 of 60 then your tissues would be at 3.2 atm so that 3.2/ 2 equals 1.6 or gf60 or 72 ft.
What's your SurfGF and how does it compare to your (Rec) GFHi?
- Thread starter Jay
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comparing to actual surface is a hard thing todo cause it appears to imply things that may not be true as taken. 33 ft to surface is a 2 to 1 ratio. gf60 would be 1.6 atm or 20 ft. if you were looking at tissues at 100 ft or 4 atm and you were at 33 ft you would have a 2 to 1 ratio also so you gf60 should be a result of moving roughly 60% of the way from 33 to 100. or I guess 72 ft. if you were at 33 ft or 2 atm and you had a gf99 of 60 then your tissues would be at 3.2 atm so that 3.2/ 2 equals 1.6 or gf60 or 72 ft.
agreed. we are on the same page Im nit saying things right.
current tissue pressure at current ambient presure is gf99. to predict the surface gf you shift to m line value to 2 instead of the m line value of 20 feet which would be 3.2. that may not be said right either but we are on the same page.
OP
Jay
Need to dive more!
Maybe this might help. Please note where Ambient is, and where the M-Value is.
Source: Gradient Factors | Dive Rite
Source: Gradient Factors | Dive Rite
That is because, for an NDL dive, the horizontal line that starts in the upper right, at the arrow that says “Ascent starts”, runs in a straight (sloped) line all the way to the left and intersects the vertical axis at or below the value for GFHi. So, no matter what GFLo is, the ascent line would never intersect it. If they did intersect, that would represent a deco stop and it would no longer be an NDL dive.
Disclaimer: The ascent line would not actually be straight. I think it would be curved, reflecting that off-gassing occurs exponentially, not linearly.
Doesn't matter: you're saturated if P insp = P amb. When you change P amb, the difference between P amb and P insp is X at time t0 and X/2 at t0 + compartment's half time. I.e. you can construe an ascent profile that would take a tissue compartment from saturated to 0.5 of M0 -- my "5 m in 5 min" example was grossly oversimplified and numerically wrong, it was just meant to illustrate how.
Who cares anyway: fast compartments don't go over M-values if you stick to slow ascent rate and slow compartment never matter at all on no-stop dives. That leaves you with a only couple of "middle" compartments really, which is how DSAT does it. If you know which one you've "loaded", you can work out how long to spend at safety stop to drop its "surfing grapefruit" down to point-five.
If you believe your tissues have compartments in 'em, that is. And/or that 0.5 is "safer" than 0.8.
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