Riding deco ceiling on ascent

[J-Vo]

You're posing a similar question to "why not increase your GFs?". Presumably they are what they are for any number of reasons, but some related to perceived risk. If you are OK with a higher value on an ongoing basis, you probably would have already increased it.

If your still below your ceiling, you haven't busted your GF settings. It's not uncommon (for me) to exit the Eye at Devil's and hop over to Little Devil with a one or two foot ceiling. I'm still below my specified GF settings. Biggest concern is binging hauled up to the surface by some drunk teenager.

 

[inquis]

This paper also speculates that "... later these fast tissues become
undersaturated and any bubble that may have formed will shrink"

That was the one statement they made that didn't make sense to me. During ascent, fast tissues cannot go any lower than ambient, a.k.a., "saturated". (Edit: I'm assuming no switching to a higher fraction of inert gas, which doesn't seem much of a stretch.)

 

[NothingClever]

Similarly, this discussion assumes two possibilities--1) stay at scheduled decompression stop depth or 2) ride the ceiling. If you know you have a ceiling that is, say, 8 feet above your current scheduled deco stop, is there any reason you can't ascend to, say, 4 feet shallower?

I'm with you on that. If my DPS produces a stop during pre-dive planning (thus making it onto my slate) and my Perdix calculates that I don't have an obligation at that stop, I'm going to continue to the next stop. I think that's different than "riding one's ceiling".

 

[inquis]

It's not uncommon (for me) to exit the Eye at Devil's and hop over to Little Devil with a one or two foot ceiling.

Sure, and that's testing -- thanks for the data point. However, it's not nearly to the extent of riding the ceiling up from significantly deeper as a matter of course.

 

[inquis]

my Perdix calculates that I don't have an obligation at that stop, I'm going to continue to the next stop. I think that's different than "riding one's ceiling".

Yes, that's different. Riding the ceiling is having a stop at 60 ft due to a ceiling of 55 ft, and you go to 56 ft and ignore your Perdix's continued warning while ascending from there at the same pace that the ceiling abates.

 

[dmaziuk]

That was the one statement they made that didn't make sense to me. During ascent, fast tissues cannot go any lower than ambient, a.k.a., "saturated".

Yeah, from the context they probably meant "not supersaturated anymore" but it's a poor choice of word.

 

[dmaziuk]

I'm with you on that. If my DPS produces a stop during pre-dive planning (thus making it onto my slate) and my Perdix calculates that I don't have an obligation at that stop, I'm going to continue to the next stop. I think that's different than "riding one's ceiling".

This discrepancy is likely to become more pronounced if you planed the stops where the ceiling is instead of the 3 msw intervals. If true, that would be an argument for sticking with the "standard" stop spacing.

 

[Wibble]

When I’m hanging around bored doing yet more deco, I’m doing it for one reason only; I don’t want DCS. I know that if I follow the schedule at my preferred Gradient Factors (50:80) I almost certainly won’t get bent, not least as I’ve spent hundreds of hours at deco and I’ve not been bent yet.

I could choose to reduce the inbuilt conservatism. But I don’t because …. I don’t want DCS.

Why would anyone want to fly so close to the sun that the inevitable happens?

Thus stops are at 3m/10ft intervals. The final stop is set to 3m/10ft but never used, something like 4.5m/15ft is easier to hold especially with waves. It’s easier to just hang around at one level doing nothing but watching the SMB reel bounce up and down a few feet in front of me.

 

[NothingClever]

This discrepancy is likely to become more pronounced if you planed the stops where the ceiling is instead of the 3 msw intervals. If true, that would be an argument for sticking with the "standard" stop spacing.

I use 3msw intervals in Multi-Deco, Baltic and my Perdix.

I didn’t learn about “continuous ceiling” in my AN/DP and Trimix coursebooks or training so until I hear about it from a reputable source, I think I’m going to chalk it up as interesting forum chatter.

 

[dmaziuk]

I use 3msw intervals in Multi-Deco, Baltic and my Perdix.

I didn’t learn about “continuous ceiling” in my AN/DP and Trimix coursebooks or training so until I hear about it from a reputable source, I think I’m going to chalk it up as interesting forum chatter.

I first read about it in Buhlmann's Decompression Sickness so it's been around, in reputable circles, since at least 1984.