GUE (and other non-PADI) Open Water Standards for No-Deco Limits

[Bob DBF]

The hardest line I got from all my GUE training and diving with GUE divers was to never exceed the training limits taught in the course - not someone else's course, the one I took.

That's the red line. Every agency has one.

Just because those training limits, ascents, etc don't match up with a different agency doesn't automatically make them bad examples.

I'm just trying to understand the parameters of those limits, the confusion was caused by comparisons that sounded like a justification rather than an explanation.

To me, "bright red line", "fuzzy area" and "fuzzy area is wide" are not compatible with each other. Where does your line start?

One has to choose a method for dealing with decompression, even though there is room for different interpretations and algorithms that will work. My training for tables or my computer depending on how I'm making the dive.

Deco and physiology being what it is, someone using this conservative method could still get bent and someone diving with their red line in the middle of that same band not.

Yes but not using any method, because none are perfect, or switching one to another on the same day, to get longer dive times, seems like it would create more problems than choosing to use one.

It's an adaption of an existing set of tables, I am not sure exactly which.

NOAA, from @rjack321 above.



Bob

 

[PfcAJ]

I planned two NDL dives both on Nx32, GF = 20/80 and I looked at the remaining NDL and I don't see where they are close at all.

Dive 1: 90 ft/25 min, 60 ft/25 min, 30 ft/25 min. NDL remaining after 25 min at 60 ft = 24 min.
Dive 2: 60 ft/75 min. NDL remaining after 75 min at 60 ft = 7 min. (60 ft is the average depth of dive 1).

if the average of the total dive time (25 min) is used for dive 2 the remaining NDL = 57 min.
Please explain how using the average depth makes the dives close?

What software are you using? I want to recreate what you’re seeing.

 

[eelnoraa]

I don't understand what is the fuzz about this. GUE min deco table is for recreational dive. GUE's rec dive profile is max 100ft with 32% or 30/30. Min Deco, although the name has "deco" in it, it is an ascent strategy. It is not a hard ceiling mandatory deco.

I am also PADI AOW/Rescue trained. The same also was taught in PAID's table, which says if you are into the gray or black(limit) zone, 3 min safety stop at 15ft is required. Does it make it a hard ceiling deco dive, I don't think so.

In a sense, the intention for the table to be used is exactly the same similar between different agencies, the value is similar. The detail of how the table is used is different. There is no right or wrong way as long as it is safe.

 

[elgoog]

@Bob DBF From your most recent post, I don't think we're disagreeing on anything here. I do want to ask where you got the below from - no one is advocating doing this. If we use GUE tables or the "130 rule" you have to use the same method for all dives.

Yes but not using any method, because none are perfect, or switching one to another on the same day, to get longer dive times, seems like it would create more problems than choosing to use one.

@EFX In your dive 1 example, you're off-gassing a fair bit at 30ft which is why you're seeing the higher NDL. Whether it's good practice to go back down to 60ft after a 75min dive where you spent the last 25min at 30ft is another topic entirely.

 

[tursiops]

Whether it's good practice to go back down to 60ft after a 75min dive where you spent the last 25min at 30ft is another topic entirely.

It has not been a topic worth discussing since 1999 when the Smithsonian conference was run and the conclusion was reached (Reverse Dive Profiles Workshop Review.) that there is no problem with reverse profiles so long as you manage your nitrogen. Using average depths and assumed non-reverse profiles is NOT managing your nitrogen. Tables won't do this for you either.

 

[seeker242]

Dive 1: 90 ft/25 min, 60 ft/25 min, 30 ft/25 min. NDL remaining after 25 min at 60 ft = 24 min.
Dive 2: 60 ft/75 min. NDL remaining after 75 min at 60 ft = 7 min. (60 ft is the average depth of dive 1).

Where are you getting 25 mins @ 60ft for dive one? You spent 75 min on dive 1, not 25. If you are meaning you have 24 min of NDL showing, after you just completed the 60' portion of dive 1, then an accurate comparison would have to be, for dive 2, a 50 min dive to 75'.

if the average of the total dive time (25 min) is used

You don't average time, only depth.

 

[Bob DBF]

I do want to ask where you got the below from - no one is advocating doing this.

Probably didn't do a good enough intro, but it would be the alternative to not picking a red line because one might get bent by choosing one.

I don't see any disagreement, I'm just trying to clarify a few questions in my mind. And GUE seems to be a bit of an odd duck among agencies teaching OW.



Bob

 

[elgoog]

@tursiops Fair enough on the reverse profile research. My statement about offgassing at 30ft and its impact on NDL still stands.

The reason I mentioned it was that when we were discussing this table in Fundies, we talked about this type of profile in the context of using average depth with the table/formula. For our scenarios, it ended up working out to average depth being too aggressive.

I'm going to bow out of this thread (and most likely all other GUE related threads). There's a lot that goes into understanding the reasoning behind the GUE protocols that's covered in the classes and not readily apparent from the documentation or forum posts. There's far too much misinterpretation going on based on assumptions and I don't think I'm doing a good job in clearing those up.

If you want to understand the GUE philosophy, your best bet is to take a class.

 

[taimen]

Just to be clear Bob. There is no deco, there is no deco ceiling, there is no one min of acceptable deco--I don't know what Taimen is talking about. I think what he is trying to say is that all the max NDL times are based on using 20/85 GF. The GUE table mirrors Padi/is very close to recreational NDL times for 32%.

From the GUE table (posted in this thread earlier): Min deco time for 100fsw/30msw dive is 30 minutes. This puts you under a ceiling after 20 minutes (based on 20/85).
You won't violate that ceiling with a GUE min deco ascent.
But it is a ceiling if someone defines NDL as "direct ascent" without any stops (at what speed?). Someone could hit this ceiling with CESA for example (not taught by GUE I think).
@Bob DBF is this what you meant?

 

[Bob DBF]

But it is a ceiling if someone defines NDL as "direct ascent" without any stops (at what speed?). Someone could hit this ceiling with CESA for example (not taught by GUE I think).
@Bob DBF is this what you meant?

Yes.

No Decompression Limits means there are no decompression stops, or any other decompression requirement to to limit a direct ascent to the surface at the, now recommended, rate of 30 fpm, but since the tables were designed for 60 fpm, 60 fpm should not be exceeded.

Rec I limit is 70', from one of the posts, and there may not be a ceiling under those conditions. If you could run that, at least I would be interested. However, you are showing graphically why the GUE tables are not labeled NDL. I can understand why GUE has an emphasis on procedure and deco discipline since using the table one would need it.


Thanks

Bob