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

[taimen]

So at some point in the dive you may have a deco ceiling preventing direct access to the surface, that is not NDL diving.

Yes. But afaik the table is.constructed so that the maximum stop length is under 1 min, using GF 20/85. The profile does not follow that ceiling, it has deeper stops than the 1 minute stop which would be at 3m.
You seem to have a very strict apporach to ndl vs deco. How do you define that absolute ceiling?One divers ndl is other divers deco. How deco algorthm parameters affect real life risk is not really known. Thus this 1 min under 20/85 ceiling with a slower multi step ascent is as good as anything.
And indeed, gue mdl table is ndl when you compare it to padi tables.

 

[CptTightPants21]

NDL does not mean that every dive is not a deco dive, it means there are No Decompression Limits to the dive.



I guess you and/or GUE has a different attitude towards No Decompression Limits that any other agency, as all that I know of have a hard line against violation of NDL. I understand, having been diving for over 50 years, and doing my share of deco, that one minute of deco probably won't hurt you, but it sets a bad example for divers that are OW trained these days.
Playing change the tables, or computer, because one finds themselves inconveniently in deco is not the mindset I would want to be teaching divers either.



So at some point in the dive you may have a deco ceiling preventing direct access to the surface, that is not NDL diving.



Is the table an algorithm made and researched by GUE, like PADI RPD, or is an adaptation of an existing set of tables/algorithm to fit a different concept of diving?


Sorry to ramble on so much


Bob

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%.

Min Deco is more a name for an ascent strategy where rather than ascend quickly to 15 feet and do a 3 min safety stop, you go up at a steady and consistent 10ft a min ascent rate when you get closer to the surface rather than ascend quickly and stop at 15 min all at once. It a

Because the gas is ALWAYS 32% nitrox, there are some rules and quick mental calculations that work with regards to dive planning and will allow you to mirror recreational dive tables. These rules/mental calculations are meant for 32% only and will begin to deviate with other nitrox mixes. The rules again mirror or are extremely close (within 1-2 min) to recreational tables.

 

[barth]

I thought they use some kind of ratio deco?

We did use deco software on our smartphone in 2016 when I did tech 1. We had different smartphones and deco software and did use multi deco and IDeco. We compared the results and decided which plan we wanted to use.

We did learn pragmatic/ratio deco. But we didn’t use it for dive planning. It was just a tool to give an impression of tech 1 dives bottomtime and depth. But we did plan all the dives with deco software on our smartphones.

 

[Magnus Lundstedt]

Avg depth IS a reasonable determinant of ongassing and offgassing.

Play with it in some deco software. It’s extremely close in all but the most wacky and unrealistic of scenarios, and even then it goes from “extremely close” to “very close”.

i did.

it seems that it is very different if i do those 2 dives:

drop to 30 meters, stay for 20 minutes, go up to 10 meter,s stay for 20 minutes, go to 3 meter.
drop to 10 meters, stay for 20 minites, go dow to 30 meters, stay for 20 minutes, go to 3 meter.

but bothe have nearly identical avg depth.

 

[Bob DBF]

Just to be clear Bob. There is no deco, there is no deco ceiling, there is no one min of acceptable deco...

And one could wonder why I'm confused. So one could make an emergency ascent from any point in the dive without violating a ceiling.


My other question hasent been answered yet, so I wonder if you could help with an answer. Is the table an algorithm made and researched by GUE, like PADI RPD, or is an adaptation of an existing set of tables/algorithm to fit a different concept of diving?

You seem to have a very strict apporach to ndl vs deco.

Yeah, that's from seeing divers bent or worse. I started when there were just the old Navy tables and there was less wiggle room than now, even then you won't know how much you can fudge untill you are bent. From what I see, for the most part, modern OW divers do not have the knowledge or skills to deal with deco diving, assuming they even know that they have gone into deco.

One has to make deco a bright red line, even though it is in a real fuzzy area, that fuzzy area is wide enough to hurt or kill you, it has happened to others.


Bob

 

[rjack321]

My other question hasent been answered yet, so I wonder if you could help with an answer. Is the table an algorithm made and researched by GUE, like PADI RPD, or is an adaptation of an existing set of tables/algorithm to fit a different concept of diving?

The values are from NOAA IIRC. The only part which is altered is the spreading out of the safety stop across 30/20/10ft.

 

[PfcAJ]

i did.

it seems that it is very different if i do those 2 dives:

drop to 30 meters, stay for 20 minutes, go up to 10 meter,s stay for 20 minutes, go to 3 meter.
drop to 10 meters, stay for 20 minites, go dow to 30 meters, stay for 20 minutes, go to 3 meter.

but bothe have nearly identical avg depth.

Both of those dives allow you to make an immediate controlled ascent after completing those time/depth combos.

So does 20m (the avg depth of both of those profiles) for 40mins.

 

[elgoog]

I guess you and/or GUE has a different attitude towards No Decompression Limits that any other agency, as all that I know of have a hard line against violation of NDL. I understand, having been diving for over 50 years, and doing my share of deco, that one minute of deco probably won't hurt you, but it sets a bad example for divers that are OW trained these days.
Playing change the tables, or computer, because one finds themselves inconveniently in deco is not the mindset I would want to be teaching divers either.

Nowhere did I say anything about violating NDL. Nor did I bring up changing tables, computer, etc to "conveniently" not be in deco. What I'm saying is that there are multiple tables and multiple computers and most of these don't line up exactly as far as NDL - certainly not down to the minute.

How many times has SB discussed Suunto vs other computers in terms of NDL difference and Suunto being "too conservative"? I found my PADI and SSI tables and they have different NDLs for the same depth. For 18m, PADI says 56min is NDL and SSI says 50min. Is a PADI instructor teaching the RDP during AOW setting a bad example for a student trained using SSI tables during OW? 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. Just because those training limits, ascents, etc don't match up with a different agency doesn't automatically make them bad examples.

So at some point in the dive you may have a deco ceiling preventing direct access to the surface, that is not NDL diving.

This is incorrect - if you use the table as intended and covered in the training, you never have a deco ceiling. GUE's ascent strategy is designed to enable a controlled ascent. The training also emphasizes planning gas and handling emergencies at depth in a way that allows you to do that slow ascent.

Is the table an algorithm made and researched by GUE, like PADI RPD, or is an adaptation of an existing set of tables/algorithm to fit a different concept of diving?

All of GUE's documentation mentions the reference standard of GF20/85 for planning dives. I was unable to find any information specifically pertaining to the algorithm or ratio used in that table. Maybe a GUE instructor will be able to provide that information. @johnkendall ?

One has to make deco a bright red line, even though it is in a real fuzzy area, that fuzzy area is wide enough to hurt or kill you, it has happened to others.

To me, "bright red line", "fuzzy area" and "fuzzy area is wide" are not compatible with each other. Where does your line start? At the beginning of the wide, fuzzy area? That would mean seeking out the most conservative dive computer and/or tables and using those. 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.

 

[CptTightPants21]

And one could wonder why I'm confused. So one could make an emergency ascent from any point in the dive without violating ceiling.

Yes, you can make an emergency ascent. Only risks you are exposed to are the same risks one would be exposed to for skipping the 3 min safety stop.

My other question hasent been answered yet, so I wonder if you could help with an answer. Is the table an algorithm made and researched by GUE, like PADI RPD, or is an adaptation of an existing set of tables/algorithm to fit a different concept of diving?

It's an adaption of an existing set of tables, I am not sure exactly which. I remember comparing it to my SSI nitrox tables and the times were either identical or similar to the point that I concluded it wasn't vodoo or completely out of line and moved on.

 

[EFX]

Avg depth IS a reasonable determinant of ongassing and offgassing.

Play with it in some deco software. It’s extremely close in all but the most wacky and unrealistic of scenarios, and even then it goes from “extremely close” to “very close”.

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?