Turn Pressure Tec Deep

[elmo]

we'll switch back to imperial for easy math

I haven't heard that before. But nice explanation

 

[Kazeone]

Just to note for others, that will work for metric units and an AL80. Other sizes and imperial units will not.

Is "Gas needed" the gas for sharing ascent?

Correct. It is just a metric example.
All your ascent gas needs to surface or gas switch. Following rule of thirds.

 

[RainPilot]

Gas needed/11.1=X
Start pressure/3=Y
X+Y=TP

Correct. It is just a metric example.
All your ascent gas needs to surface or gas switch. Following rule of thirds.

Ok, I get the principle but I am not sure of the maths...
Using a 10L, 300 bar tank just to make the maths simpler:
Start pressure/3 = 100 bar = Y
If I need 2000L of gas for the ascent, that gives me X=200 bar.

Thus, my TP = X+Y=300 bar = tank total = can't do the dive (or no moving from the ascent point anyway).

My method would be to remove the ascent gas from the total, then divide the remaining usable into 3rds to decide on penetration. The change would be that in my use, Y= (start pressure-X)/3

In my example:

X=200 bar
Y=(300-200)/3 = 33bar
TP=X+Y=233 bar

This would allow me to go 33 bar out and 33 back, leaving a 33 reserve for my buddy to get back with me.