How can I calculate accelerated deco and res nitrogen times?

[battles2a5]

So, I'm taking advanced nitrox/deco right now and I'm wondering if there is a way to manually calculate accelerated deco times using a rich deco mix and the associated rnt's. My text doesn't go into it, my instructor uses standard navy tables and sticks to the deco times for air to pad the deco, and all of the other resources I have seen either use purpose-built tables (e.g. IANTD Buhlman + Accelerated on 75%) or software (V-planner, deco planner, etc.). So is there a way to manually calculate the accelerated deco stop times using formulas? I don't plan on working these out manually for my dive planning, I just want to have a better understanding on how rich deco mixes effect deco times and how to plan accordingly. Thanks in advance!

Ryan

 

[ianr33]

My rule of thumb when diving air is that using 50% for deco will halve the length of stops and using 100% O2 will reduce stops by a factor of 3 i.e. a 15 minute stop on air will be only 5 minutes on O2.
If you play around with V-Planner you will see that that these rules hold amazingly well (within a minute or 2)
Of course you should always be diving with the appropriate tables and only guesstimate deco in dire circumstances.

 

[The Chad]

I've done the same thing as ianr33 just to give a rough idea. However if your using 36 and 80 or anything else it quickly becomes a pain. I would never dive with any of the rough ideas and always go with Vplanner or If your in it for the long haul get a VR3, plug in your gases and plan your dive

 

[grazie42]

You can do it manually...the easiest way would be to look up the code for one of the open source decoprograms out there...in the code you´ll find the formulas used to calculate the output of the decoprograms...it won´t be easy and the math is "a bit" above highschool level so you may find it a bit of a challenge...it can be done though if you REALLY want to...

For understanding how different variables effect the decoschedule, I´ve found it helpful...

Bruce Wienke also wrote a book called "the basics of decompression" or something like that which will also "get you started"...

 

[battles2a5]

Thanks for all the info. Grazie, I'll definitely have to check out some of the open source programs. I think some of them were posted on TDS recently. I'll see if I can figure it out.