Manual calculation for accelerated deco

[Dan_P]

I guess I understood the literal meaning of the words--I have no idea what it means in this context. It is the most important factor in altitude diving--how is it completely out of context?

What's relevant is not the 20% difference between 1,0 and 0,8 - unless we're doing a 2000m vertical traverse.
It's the delta across relative pressure difference on a sea level dive and for example a 2000m dive.
That would be contextual.

I'm not trying to ridicule you. We've previously had a discussion on the subject of bouyancy, which was why I mentioned it here - unfortunately, that caused a lot of confusion which I've subsequently aimed to clear up.
But - yes, I agree, let's leave that to a side.
As decompression goes, I've clarified my position on that bit, above.

 

[tursiops]

What's relevant is not the 20% difference between 1,0 and 0,8 - unless we're doing a 2000m vertical traverse.
It's the delta across relative pressure difference on a sea level dive and for example a 2000m dive.
That would be contextual.

So if I'm at 30m depth at sea level, I have 3ATM of water pressure to release to get to the 1ATM surface.
At your 2000m altitude, I have 3.2ATM to release at the surface. (disregarding fresh and salty)
That causes two effects: (1) 0,2ATM is like being 2m deeper at sea level ("theoretical" vs actual depth), and (2) when I finally get to the surface I'm at a lower air pressure, so my off-gassing is faster, hopefull not too fast, so I need to take that into account. In fact, if my tables/algorithms are designed for offgassing at (say) 6m, I need to be shallower than that so the pressure differential is correct. 6m at sea level would be a pressure differential of 1.0/1.6=0.625. But at 2000m, at 6m depth, the differential is 0.8/1.6=0.5. So that 6m (at sea level) stop becomes a 3m stop to get the same differential. How does RD take all this into account? If it ignores it, it is ignoring physics, which is kinda...well....unscientific. If it does it by guess-and-by-golly-that-feels-better-now, then it is....well...unscientific.

I'm not saying RD doesn't work. I'm saying it is not scientific, i.e., not based in science.
That's MY context.

 

[KevinNM]

Where can I officially buy GUE's and UTD's current RD implementation?

I don't think GUEs is covered outside of the tech courses. The course notes have a summary, but I don't know what is added by the instructor during that block. It's often quite a bit.

 

[PfcAJ]

Where can I officially buy GUE's and UTD's current RD implementation?

You can buy GUEs info by taking tech 1 and 2.

In summary it’s “hey look, at this depth with this gas for this time range there’s a ratio between depth and deco time outputted by buhlmann and/or VPM. You can use this to remember deco schedules through this range of depths and times with these gases. Pretty neat! Always refer to the algorithm though and if the RD deco time doesn’t match the algorithm, follow the algorithm as it’s primary”.

It’s not something crazy fancy.

 

[lowviz]

I don't think GUEs is covered outside of the tech courses. ...

Speaking as someone searching from the outside, that appears to be true. I was able to get a UTD mini course at a reasonable cost and that should be close enough to give me a basic comprehension of RD.

It is something I should have attended to long ago. Forget Tech 1 and 2. Sorry, I'll never be GUE/UTD as both camps keep insisting on a buddy, but I remain curious as to how much mental math at depth is required if one needs to 'recalculate'.

I remain, by my own description, "DIR friendly". No axe to grind, just interested...

 

[Dan_P]

So if I'm at 30m depth at sea level, I have 3ATM of water pressure to release to get to the 1ATM surface.
At your 2000m altitude, I have 3.2ATM to release at the surface. (disregarding fresh and salty)
That causes two effects: (1) 0,2ATM is like being 2m deeper at sea level ("theoretical" vs actual depth), and (2) when I finally get to the surface I'm at a lower air pressure, so my off-gassing is faster, hopefull not too fast, so I need to take that into account. In fact, if my tables/algorithms are designed for offgassing at (say) 6m, I need to be shallower than that so the pressure differential is correct. 6m at sea level would be a pressure differential of 1.0/1.6=0.625. But at 2000m, at 6m depth, the differential is 0.8/1.6=0.5. So that 6m (at sea level) stop becomes a 3m stop to get the same differential. How does RD take all this into account? If it ignores it, it is ignoring physics, which is kinda...well....unscientific. If it does it by guess-and-by-golly-that-feels-better-now, then it is....well...unscientific.

I'm not saying RD doesn't work. I'm saying it is not scientific, i.e., not based in science.
That's MY context.

Mate.
The pressure at 30m on a dive at 2000m is 3,8 and 0m is 0,8.

The pressure at 30m on a dive at sea level is 4,0 and 0m is 1,0.

The total pressure drop is 3,0 in either case.

It's a matter of relative pressure differential.

I've explained how RD works, and how I approach the matter at hand.
What you're asking for, is a set of evidence in a world where none exist, regardless which solution you apply.

 

[tursiops]

Mate.
The pressure at 30m on a dive at 2000m is 3,8 and 0m is 0,8.

The pressure at 30m on a dive at sea level is 4,0 and 0m is 1,0.

The total pressure drop is 3,0 in either case.

It's a matter of relative pressure differential.

I've explained how RD works, and how I approach the matter at hand.
What you're asking for, is a set of evidence in a world where none exist, regardless which solution you apply.

Your reading comprehension sucks.

 

[PfcAJ]

Speaking as someone searching from the outside, that appears to be true. I was able to get a UTD mini course at a reasonable cost and that should be close enough to give me a basic comprehension of RD.

It is something I should have attended to long ago. Forget Tech 1 and 2. Sorry, I'll never be GUE/UTD as both camps keep insisting on a buddy, but I remain curious as to how much mental math at depth is required if one needs to 'recalculate'.

I remain, by my own description, "DIR friendly". No axe to grind, just interested...

It’s not prticularly difficult. Everything is broken up in into 5min segments and 10ft depth increments.

So as an example maybe you’re 10ft deeper than you “planned”. That extra 10ft racks on an extra 5mins of deco time. So in order to maintain the same total deco time your bottom time gets decreased by 5mins. It’s pretty slick.

 

[Dan_P]

Your reading comprehension sucks.

We've already been over how I approach the matter at hand.
We've touched on what RD is, and is not.
I've explained why "it's unscientific" is a silly statement.
I'm saying if you think there's a 3,2 bar pressure drop between 30m and 0m, you're "kind of....well...unscientific".

If you mistake my willingness to carry out a full-on repeat of this discussion for you with lack of comprehension, you're mistaking lack of patience with inaptitude.

It's just we've quite simply already been over everything you said, at least once.

 

[victorzamora]

I've made a simple fix (in bold), but agree otherwise.

Mate.
The pressure at 30m on a dive at 2000m is 3,8 and 0m is 0,8.

The pressure at 30m on a dive at sea level is 4,0 and 0m is 1,0.

The dive from altitude has a 4.75x pressure increase while the dive from sea level has a 4.00 pressure increase.

It's a matter of relative pressure differential.

I've explained how RD works, and how I approach the matter at hand.
What you're asking for, is a set of evidence in a world where none exist, regardless which solution you apply.