Breathing O2 during surface interval

[boulderjohn]

What depths are you diving to and what are the bottom times? How long do you wait before driving home after a staged decompression dive? Do you rely on altitude calculators?

On the day I drive home, my dive might be any of a variety of depths, with the maximum about 280 feet. If we go to 280 feet, the bottom time will be 20-25 minutes, for a total run time of 110-120 minutes. I usually exit with a GF of 70. Nothing huge. Before leaving, we will usually eat lunch and then pack up, taking 1-1.5 hours. The first hour of the drive is a gradual ascent of about 2,000 feet, supposedly within the range of a safe ascent after diving. I will be breathing oxygen that whole time. Then it is another 1.5 hours before the next ascent for a total of 3,200 feet of ascent from the dive site. I will be breathing oxygen for at least half that time, sometimes all. If I breathe it the whole time, I will have breathed it longer than the astronauts do before taking off.

According to the Shearwater graphics, I should be good even if breathing air.

Please note that in telling what I do, I am not recommending it to others. I never do.There is nothing official to support this. Consider me a renegade.

This is all spelled out in the Ascent to Altitude article I wrote.

 

[Scuba Client]

On the day I drive home, my dive might be any of a variety of depths, with the maximum about 280 feet. If we go to 280 feet, the bottom time will be 20-25 minutes, for a total run time of 110-120 minutes. I usually exit with a GF of 70. Nothing huge. Before leaving, we will usually eat lunch and then pack up, taking 1-1.5 hours. The first hour of the drive is a gradual ascent of about 2,000 feet, supposedly within the range of a safe ascent after diving. I will be breathing oxygen that whole time. Then it is another 1.5 hours before the next ascent for a total of 3,200 feet of ascent from the dive site. I will be breathing oxygen for at least half that time, sometimes all. If I breathe it the whole time, I will have breathed it longer than the astronauts do before taking off.

According to the Shearwater graphics, I should be good even if breathing air.

Please note that in telling what I do, I am not recommending it to others. I never do.There is nothing official to support this. Consider me a renegade.

This is all spelled out in the Ascent to Altitude article I wrote.

At an altitude of 2k feet, your actual actual depth is 280 FSW, which gives you a theoretical Ocean Depth of 293 FSW. I use GF40/70. My mind was muddled earlier probably because I use different terminology: off-gassing, nitrogen still in solution, bubbles, No flying after diving etc. Thanks for breaking it down. The other question is irritation of the lungs from being on O2 for so long. But then the PO2 is low. I don't consider you a renegade, I consider you a thinking diver. Will read your blogs again.