acsent to altitude after diving a computer

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haumana ronin

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How do you safely ascend to some altitude after diving at sea level on a computer? I have seen the "Required Surface Interval Before Ascent to Altitude After Diving" table posted here and in the NOAA manual. It seems like you need pressure groups to use that table right? I dont think computers have a highest-pressure-group-in-the-last-24-hours function. Do I back into the pressure group calculation, keep good notes, and apply that?

:zen:
 
Great question. You have given a reason that is rational for doing something I do compulsively. Even though I have used a computer on every dive I have ever been on, I calculate the pressure group for each dive using the methodology for multilevel dives. I have even been known to use the obsolete "wheel" ( which is not obsolete, jut not taught anymore) to do this, though you can do it with the RDP. It became a necessity when shore diving on Kona a couple of years ago, where the drive back to our hotel from the sites we dove hit elevation of over 1400 feet. As we had been doing multiple dives daily over several days,and would be doing so the next few days, we were being conservative. I think rdp multilevel dive pressure group calculation is an important skill for people who dive independently, and want to create a safe and specific dive plan. I'm old school. Or maybe I'm just old. Or both.
DivemasterDennis
 
Bear in mind that the pressure group letter designations you get from many recreational dive tables, such as PADI's RDPs, are not the same as NOAA's.
If you are going to use NOAA's ascent to altitude tables, you should also use their basic tables, or equivalents (such as the USN's).
 
You might find this short article by Dr. Edmund Kay helpful. His recommendations are independent of particular tables and groups. I use his factors when diving around here and traversing mountain passes shortly after. Note that he admits these are rough guidelines only.

Altitude Exposure After Diving

-Bryan
 
I live at 8800'. I dive at 5000' and routinely drive home after a dive. The dives are generally not pushing NDL's but sometimes they are when we dive the BH, NM. At BH we are diving at 5000' and 8-10 hours later I am at home at almost 9000'. The drive is 6 hours but we hang out for a few hours before the drive as it has a 8,000 pass and quick altitude gains upon leaving.

I am not recommending this but its what I have been doing for years on average 6+ times a year. As I live at altitude and have for two decades so I am acclimated. Your results may differ.
 
So it seems there is no way of actually doing it directly from a computer. The rule from combining the last two posts seems to be wait 1 hour if you were not close to NDL, wait 3 hours if you were close to NDL, wait 8 hours if you went into deco.

It seems that figuring it out as a multilevel dive and tables is not very accurate, from reading past posts here. Also at that point, you are not really using your computer.

Is a really roundabout way of doing it to see how much time you have left at depth at the before starting ascent (assuming its not shallow and you haven't started to out-gas), convert that to NOAA pressure groups, then use their Ascent table?

:zen:
 
You might want to set the computer to higher conservatism.
My Oceanic Veo 2.0 in Pelagic Z+ mode just calculates the dive at higher altitude if set to CF1 or 2.
Of course this depends on the computer you use and only if you stay within NDL at this setting.
 
https://www.shearwater.com/products/swift/

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