Further decompression to lessen no fly time?

[happy-diver]

Technical divers who finish their dives decompressing on oxygen will usually be on-gassing in their fastest tissues during a surface interval.

The NOAA ascent to altitude tables used to tell how long you had to wait to ascend to different altitudes, depending upon what pressure group you were in. They also had a table telling you how you would move through those pressure groups more quickly if you breathed oxygen during your surface interval. (I can't find them any more.)

When I do a decompression dive and then drive home later in the day, I breathe oxygen during the first part of the drive. Just before I have driven an hour, I will ascend to aout 2,500 feet above my dive elevation. I will then hold nearly that same elevation for another hour and a half before ascending another 800 feet. I will usually breathe pure oxygen for most of that distance.

There is, unfortunately, no good data on this, so I am not officially recommending any course of action--just telling you what I do, right or wrong. If Shearwater would simply allow divers to identify a specific gas for breathing during a surface interval the way they do during the dive, that would make options pretty clear.

That ^^^ is an excellent caution.

As someone who drives to altitude after diving many times a year, this is an important topic for me. I have done enough research to know there is almost no research on it. I recently asked some very prominent and highly knowledgeable experts on decompression theory to help me write an article on ascending to altitude after diving. They politely refused. They did not want to be quoted as even appearing to advocate something that has not had enough testing to justify a recommendation.

But people have to do it. With or without an expert opinion, people have to decide what to do. So I took a deep breath and wrote an article on ascending to altitude after diving. It is located on my resources page, along with several other useful items, including the NOAA ascent to altitude table and the US Navy ascent to altitude table. You will see that I wrote as clearly as possible in two different places that nothing in that article should be construed as a recommendation from me. It is just a compilation of facts that will help you make up your own mind.

I was recently in a situation in my usual diving environment in which a fellow diver had some mild symptoms on a morning dive. They went away. We were scheduled to dive the next day. We cancelled that, and instead of driving home over the pass, we spent the night in a local motel. Was that necessary? Beats me, but if I'm going to make a mistake, that's the direction I want to make it.

Astronauts and U2 pilots breathe pure oxygen for a couple of hours and than do one horrific ascent to altitude. Theoretically, we could all do pretty much the same thing and be fine. We just need something more than theory to give us the confidence to do it.

Brilliant!
Keep taking those deep breaths

Oh yeah, I drive home on 02 from all dives, not constantly, spit out the reg at traffic lights
no hills no fly, for years and years

 

[JohnnyC]

I'd love it if @Shearwater had a SurD option. I think it would be a fun option to play with.

 

[boulderjohn]

I'd love it if @Shearwater had a SurD option. I think it would be a fun option to play with.

I was recently given an idea via private message from someone with very significant credentials. Since it was via PM, I ill omit his identity. He said to put the computer in water while you are breathing the oxygen.

 

[rjack321]

I was recently given an idea via private message from someone with very significant credentials. Since it was via PM, I ill omit his identity. He said to put the computer in water while you are breathing the oxygen.

Or you could just stay in the water on the O2 and watch the pretty bars go down, that's what I do.

 

[boulderjohn]

Or you could just stay in the water on the O2 and watch the pretty bars go down, that's what I do.

I breathe that surface oxygen a long time before ascending to altitude.

 

[rjack321]

I breathe that surface oxygen a long time before ascending to altitude.

What's your altitude delta?
I usually fly about 12 hrs after a week of deco diving. I make the last dive the shallowest and pad the O2 stop, although I am cognizant that by doing a CCR nitrox dive last instead of a helium dive I might actually be making my residual gas loads worse instead of better.

 

[dberry]

I was recently given an idea via private message from someone with very significant credentials. Since it was via PM, I ill omit his identity. He said to put the computer in water while you are breathing the oxygen.

Isn't there a minimum depth to trigger "auto-on" for most PDCs? Something on the order of 1 meter... Won't you need a decent barrel of water to "fool" the PDC while you're on O2?