Deco Stop times

[andibk]

Dr. Deco
I was just using the V planner planning out a 40 meter deco dive with 45 minute bottom time on 28% 02. The deco I used 50% on all stops. When I punched in the profile it read as such

12meter 4 minutes
9 meter 6 minutes
6 meter 4 minutes
4.5 meter 20 minutes

Why would the 6 meter stop be less time then the 9 meter stop?? There was no change of gas at all on this deco profile.

Bruce

 

[Rick Murchison]

The apparent glitch you're seeing is because you have a final stop at 4.5M, which the program "looks ahead" to. Since the 6M stop only needs to prepare you for an ascent of 1.5M to the next stop, that stop is shortened. If you'll plug 3M vice 4.5 as your last stop, you'll get increasing times at each stop.
Rick

 

[ScubaJorgen]

Rick is right.

A deco program calculates the time it takes for the tissue tension to drop to the level that is safe at the next stop depth. I.e. the time you should stay at current stop.

After this period tissue tension in each compartment has dropped that much, so that for each tissue compartment the tension is lower than (or equal to) the max. allowed value at the next stop (M-value). Now the diver can proceed to next stop ut:.

Smaller increments to next stop mean smaller times to stay at current stop.

Deco programs may take into account offgassing during the ascent to next stop. This makes things a bit more complicated. However, it does not change the principles above.

 

[vlada]

group where you can also ask this question

v-planner group

 

[BIGJC]

Switch to oxygen for deco... your better off.

:nolurk: