Understanding bailout values in simulation mode

[mobu]

Hi,

I have done a simulation in CC mode and I have a doubt.

These are the simulation data:
Diluent: TX17/37
SP: 1.3
BT: 12'
Depth: 60m
GF: 50/85
SAC Work: 18L/min
SAC Deco: 16L/min
Bailout: TX18/43 (first) and NX50 (Deco)

These are the results referring to bailout:
from the bottom to 21m I breathe TX18/43. Consumption= 611L
From 21m to 3m breathe NX50. It takes me 23' of Deco. Consumption= 638L

My doubt:
doing some quick calculations referring the consumption of TX18/43.
From bottom to 21m aprox 40m. Ascending 10m/min= 4' breathing 18/43
Average depth aprox 40m = 5 ATA
Consumption= 4 x 5 x 18= 360L

We are talking about a difference in consumption of 18/43 of almost double
Either I am doing the quick calculations wrong or I don't understand how the OSTC calculates the consumption in the simulation.

Could you help me understand this difference? Thanks

BR
Ion

[Ralph]

Hi Ion,

there is one more setting that goes into the gas consumption caculation: fTTS/Delay.
This is the time in minutes, the OSTC assumes you stay at bottom depth - while already
on bailout gas - before the actual ascent starts. This 'delay time' caters for the time
needed to assess the situation & confirm a BO ascent is needed, to signal with the
buddy and to shoot the SMB, or alike. This exta time at depth also causes some more
deco obligation, drawing even more gas later on, here on the Nx50 gas.

BR
Ralph

[mobu]

Hi Ralph,

explained and understood. Thank you!!

BR
Ion