Dive Gas Planner

Imperial gas planning using course terms: SCR, DCR, MG, UG, TP, Shearwater AI/GTR, and wet notes.

Working SCR 0.83 cf/min Deco SCR 0.50 cf/min HP100 doubles TF 6.0

Manifolded Double HP100 Planner

Use this for your primary working dive estimates.

Single HP100 Planner

Same workflow, single-cylinder gas volume.

Wet Notes Table Generator

Compact rows for manual transcription. Pick the configuration, then copy the numbers by hand.

Readable Table

Wet Notes Copy Block


          

        

      


      

        

          
Sim Scenario Crib

          
Use this for Roger-style scenario math: MG first, then UG, TP, and time.

        

        

          

            
Scenario Workflow

            
    
              
  1. Identify config. HP100 doubles TF 6. Single HP100 TF 3.
    2. 
              
  2. Find ATA. ATA = depth / 33 + 1.
    3. 
              
  3. Find PSI/5MIN. PSI/5 = SCR x ATA x 5 x 100 / TF.
    4. 
              
  4. Calculate MG. MG = two-diver emergency SCR x average ATA x ascent time.
    5. 
              
  5. Convert MG to psi. For doubles: MG psi = MG cf x 100 / 6, then round up.
    6. 
              
  6. Find UG. UG = start pressure - MG.
    7. 
              
  7. Find TP. Halves: start - UG/2. Thirds: start - UG/3. All usable: MG.
    8. 
              
  8. Find max bottom time. Time = UG / PSI-per-5 x 5, then round down.
    9. 
            

          

          

            
Head Math

            

              

                ATA
                depth / 33 + 1
              

              

                Doubles PSI/5
                SCR x ATA x 83
              

              

                Working shortcut
                If SCR is 0.83: PSI/5 ~= ATA x 70
              

              

                Deco shortcut
                If SCR is 0.50: PSI/5 ~= ATA x 42
              

              

                Sample to SCR
                Doubles 5 min sample: SCR = PSI used / (83 x ATA)
              

            

          

          

            
Worked Example

            
Scenario: 120 ft, HP100 doubles, start 3400 psi, halves

ATA @ 120 = 120 / 33 + 1 = 4.6
Working SCR = ___ cf/min
PSI/5 = SCR x 4.6 x 83 = ___ psi/5

MG:
C = 0.70 x 2 = 1.4 cf/min
A = average from 120 to 70 = 95 ft = 3.9 ATA
T = (120 - 70) / 10 + 2 = 7 min
MG = 1.4 x 3.9 x 7 = 38 cf
MG psi = 38 x 100 / 6 = 633, round to 700 psi

UG = 3400 - 700 = 2700 psi
Halves travel gas = 1300 psi
TP = 3400 - 1300 = 2100 psi

Max time = 2700 / PSI-per-5 x 5

          

          

            
Memory Anchor

            

              
Do MG first. Everything else depends on it.

              
UG = start - MG.

              
TP comes from the gas rule.

              
Time comes from UG divided by PSI/5MIN.

              
Written plan wins over GTR. GTR is live awareness, not the gas plan.

            

          

        

      


      

        

          
Today’s Measurements

          
Enter PSI samples here. The app converts pressure use into SCR and updates the planner averages.

        

        

          
          
        

        

          

            
Conversion Math

            

          

          

            
Measurement Rows

            

              

            

          

        

      


      

        

          
Shearwater AI / GTR Alignment

          
Use this to reconcile the written plan with what your Shearwater is showing during the dive.

        

        

          

            
GTR Approximation

            

              
              
              
              
              
              
              
              
            

            

          

          

            
Teric Notes

            

          

          

            
How to Read GTR

            
    
              
  • This setup assumes a Swift AI transmitter without GPS, so the planner treats it as tank-pressure data only.
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  • GTR is live feedback: time at the current depth until a direct ascent would surface with the reserve pressure remaining.
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  • Shearwater bases GTR on current SAC, averaged over the last few minutes. In course terms, this is a pressure-based surface consumption number, not SCR volume.
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  • GTR includes ascent gas, but not safety or decompression stops.
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  • For decompression or multi-gas dives, use the written gas plan and team minimum gas; treat GTR as situational awareness.
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Course terms: TEK ESSENTIALS - DIVE PLANNING, Gas Management terminology.

              
Shearwater terms: AI QuickStart Guide and Perdix AI support FAQ.

              
https://shearwater.com/pages/ai-quickstart-guide

              
https://shearwater.com/pages/perdix-ai-support