Rock bottom & SAC rate calculators

[Basking Ridge Diver]

Thank you - figured it out - I was using 30 foot ascent in my spreed sheet - now works out to 3.1 cu ft using your numbers.

 

[Kevrumbo]

Program your old HP 33s RPN Calculator (HP Focal Language of the RPN HP-41C/CV/CX machines) to total the amount in Litres of breathing gas needed for a particular dive.

Input prompts for Depth ("D") in meters, Time ("T") at that depth in unit minutes with seconds in decimal base ten format [so for example, 1min 30sec is entered as 1.5], and SCR ("S") [SCR --stands for Surface Consumption Rate, same as SAC rate in litres/min].

Program loops through your depth range, time at each depth and SCR, all the way to the surface --and yields the total gas needed in Litres.

L0001 LBL L
L0002 INPUT D
L0003 INPUT T
L0004 INPUT S
L0005 (D/10 + 1) X T X S [//comment: Depth-divided-by-10 plus 1, multiplied by Time and multiplied by SCR equals litres of gas//]
L0006 ∑+
L0007 29
L0008 STO i
L0009 VIEW(i)
L0010 D – 3 [//comment: decrement "D" depth by 3 meters//]
L0011 STO D
L0012 x ≥ 0? [//loop test: is "D" depth still equal or greater than zero? --If less than zero then exit loop//]
L0013 GTO L
L0014 CLVARS [//exit loop to total gas needed in litres//]
L0015 ∑x [//this retrieves the total gas in litres needed and places the value in all four registers//]
L0016 ∑x
L0017 ∑x
L0018 ∑x
L0019 CL∑
L0020 RTN
PRGM TOP

All the above is just a simple iterative programming application of the manual Gas Calculation exercise in the GUE Fundamentals of Better Diving Workbook. . .​

 

[Fuse]

When I first joined this site there was an excruciating thread about rock bottom that continued forever and basically turned into a giant arguement, but it was very informative for me. During that thread I asked TSandM about this rock bottom calculator and she mentioned to me then that the ascent strategy used in the calculations may not be exactly what I needed and the calculator may be a bit conservative for my diving. I later found an app "scubacalc" that I use now, I add a 200psi buffer to the pressure that they recommend and it has helped me a lot with planning. Maybe these numbers will be a little more inline with what you think are better for you and your buddies. Also, if anyone with lots more experience than me find these numbers a bit too liberal please chime in I'd like to hear that as well.
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I am looking for the app you mentioned. Does it go by a different name?

Thanks!