UTD Decompression profile study results published

[dmaziuk]

There is some truth in this. I didn't appreciate exactly how much of a kludge (and how non-'magic') gradient factors were til I programmed my own implementation. I can think of at least a couple of better ways of implementing the same concept.

@Kevrumbo is right though in that they do let user adjust their stops in a way that's, ermm... more reasonable than the alternatives?

You assumed wrong. I meant Kevrumbo's arbitrarily added shallow stops to Ratiodeco.

:sigh: humour is such a subjective thing...

 

[stuartv]

I was actually just looking at a Nitek, and when my LDS called DR to see about a price match and delivery time, they were informed that its been discontinued for a while now. apparently once they're out of stock at DGX, that's it.

Yep. But that doesn't mean DR won't continue to support them (i.e. honor warranty claims, etc.). And anyway, the real point was that there are less expensive alternatives than a Shearwater if you're looking for a multi-gas trimix computer. You don't have to spend anywhere near $2K to have 2 suitable computers. The Hollis TX-1 can also be had for around $400 (roughly).

 

[Kevrumbo]

The major difference between the two Ratio Deco Versions is how they treat the ascent from working depth:

Ascent Rates
The following are guides for use in calculating various ascent rates and profiles. Divers should be cautioned that the on-site environment will ultimately determine the final shape of the profile. This is a team process that all members must participate in. When feasible the last stop should be conducted at 6m/20ft followed by a slow ascent of 1m/3ft per minute to the surface.

Recreational
• Calculate 50% of the average depth of the dive
• Ascend at 9m/30ft per minute to the calculated depth
• Conduct a one minute stop for each remaining 10ft/3m interval
• One minute stops are executed as a 30 second stop and 30 seconds of movement to the next shallower interval

Tech 1
• Calculate 75% of the average depth of the dive
• Ascend at 9m/30ft per minute to the calculated depth
• Adjust ascent rate to 6m/20ft per minute thereafter until intercepting the gas switch or decompression profile which ever occurs first

Tech 2

• Less than 15 minutes bottom time:

◊ Calculate 75% of the average depth of the dive ◊ Ascend at 9m/30ft per minute to the calculated depth
◊ Calculate 50% of the average depth of the dive
◊ Adjust ascent rate to 6m/20ft per minute and ascend to the calculated depth
◊ Once this depth is reached adjust ascent rate to 3m/10ft per minute thereafter until intercepting the gas switch or decompression profile which ever occurs first

• More than 15 minutes bottom time:

◊ Calculate 75% of the average depth of the dive
◊ Ascend at 9m/30ft per minute to the calculated depth
◊ Calculate 50% of the average depth of the dive
◊ Adjust ascent rate to 3m/10ft per minute and ascend to the calculated depth

Versus:

UTD (formerly 5thd-x) Deepstops Table From Depth -see page 6 to 7.

(Note: the above is what was found currently on the web and doesn't reflect the latest updates on these two proprietary methodologies). . .

 

[stuartv]

The major difference between the two Ratio Deco Versions is how they treat the ascent from working depth:



Versus:

UTD (formerly 5thd-x) Deepstops Table From Depth -see page 6 to 7.

(Note: the above is what was found currently on the web and doesn't reflect the latest updates on these two proprietary methodologies). . .

These two belts are just alike. The major difference between the two is how they hold up your pants.

In other words, when you're talking about a method for calculating a deco ascent, how much more explicitly could you say they totally different than by saying "the major difference between them is how they treat the ascent from working depth"?

 

[Kevrumbo]

These two belts are just alike. The major difference between the two is how they hold up your pants.

In other words, when you're talking about a method for calculating a deco ascent, how much more explicitly could you say they totally different than by saying "the major difference between them is how they treat the ascent from working depth"?

Because @stuartv and your meaningless metaphor above aside (wtf??), UTD's current version still retains discrete deepstops while GUE's RD uses a modifying slowing ascent rate from depth.

Once again, given the implications of the NEDU Deepstops Study, the fix for UTD's RD version would be to change to modifying ascent rates instead of hard discrete deepstops; so in effect, this would mimic GUE's version and essentially be a similar implementation as GUE's Ratio Deco.

As a proposed objective solution, does this make practical sense?

 

[huwporter]

(Note: the above is what was found currently on the web and doesn't reflect the latest updates on these two proprietary methodologies). . .

Can everyone please note that these are NOT the current GUE SOPs.

 

[PfcAJ]

These two belts are just alike. The major difference between the two is how they hold up your pants.

In other words, when you're talking about a method for calculating a deco ascent, how much more explicitly could you say they totally different than by saying "the major difference between them is how they treat the ascent from working depth"?

I don't want to speak for Kev but I think he means the difference between bottom and 1st gas switch.

 

[elmo]

Can everyone please note that these are NOT the current GUE SOPs.

And also they are just the ascent rates to your first stop. No ratio deco here.

 

[elmo]

Just for the fun of it (and to complicate matters), I ran the UTD RD profile through the Subsurface dive planner: View attachment 403407

Turns out, with GFs set to 30/80 this ascent is ok (as in: never violates the ceiling).But only barely: If you lower GFhigh by a bit or slightly mess with the timing of the first gas switch to EAN50 you violate the ceiling in the final ascent. So, from the point of view of Bühlmann with GF, you would not expect any more DCS symptoms as if you let GF 30/80 directly compute your ascent.

For comparison, here is the latter plan (note well the different time scales on the time axis!):
View attachment 403408

I couldn't find the utd rd profile published, but from reading this thread I was under the impression the 9m stop was on 18/45 backgas rather than 50% nitrox.

Rick

 

[stuartv]

Because @stuartv and your meaningless metaphor above aside (wtf??)

Really, this:

Please, do not add to the confusion.

What has been tested is NOT what you are showing, UTD-RD has little to do with other RD rules. They are very different. The fact that you believe the correction to apply to UTD-RD is to make it into GUE-RD does not, by any stretch, change what has been tested. So please stop posting that "see, this is UTD if you remove everything that is UTD, and this is GUE, see how similar? They're the same!". They are not the same. Maybe UTD-RD 3.0 will be the same as GUE-RD, but the current one we can see, and has been tested, is not. Not by any stretch.