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

[seeker242]

It sounds like Rec I is not NDL diving since deco is allowed.



Deco is deco, at least that was the NDL training I received. Granted 1 minute isn't much but... Naming the table MDL rather than NDL makes my point.

Rec I seems to limit the diver to 100', regardless of experience.

Rec I would seem to limit the diver to EAN 32 or 30/30, and I would assume you are certified for those gasses during the class.


Bob

Rec 1 is essentially GUE open water training with nitrox included. It's NDL diving, as is all open water training. Max depth 70'

 

[Storker]

... but only if you have the expertise to rut the back-of-the-envelope guesstimate.

No. As I said, it depends on the type of job I'm planning to do. I'm not talking about back-of-the-envelope numerical guesstimates, I'm talking about stuff like symbolic math, phys or chem. Or designing an algorithm.

And to get back on topic, I can run a lot more scenarios using tables and perhaps a pen and a piece of paper than I can run by faffing with a computer for the same amount of time. Because I don't have to push buttons and wait for the computer to display a number, I can read the number directly from the table. IOW, if I want to get a feeling for the depth/NDL correlation, doing it on tables will be more efficient.

 

[dmaziuk]

I'm not talking about back-of-the-envelope numerical guesstimates, I'm talking about stuff like symbolic math, phys or chem. Or designing an algorithm.

Because you know symbolic math, phys or chem and the computer inputs are cumbersome.

How about if your computer was a tablet showing depth/time axes and you could plan your dive tracing a profile with your thumb?

 

[Storker]

the computer inputs are cumbersome

My point exactly.

How about if your computer was a tablet showing depth/time axes and you could plan your dive tracing a profile with your thumb?

Yes, how about that. Problem is, so far I haven't stumbled over nor heard about one single rec diving computer which looks like a tablet and displays depth/time axes. They all have a more or less puck-sized form factor, a rather small LCD screen and usually no more than two or three buttons. And teaching beginners by using a computer instead of tables normally means "using a standard diving computer".

Good attempt at pulling the discussion away from the core of the OP, though. I'll give you that.

 

[1atm]

This is one reason I'm getting confused, the other is that the name of the table does not say NDL with a 10' per minute ascent rate, it specifically does not say NDL. The NDL tables I have used have changed the recommended ascent rate and the use of Nitrox over the years so there is no reason to change the name just because of ascent rate. I have exceeded NDL because of a slow ascent rate so @elgoog post seemed to make sense, however if she is mistaken there is no reason not to label the table NDL as is the convention.

So is deco allowed or not when using the tables as directed? Inquiring minds and all...

I assume I didn't put my foot in it on the rest of my assumptions.



Bob

Deco is not allowed in Rec1 / fundamentals, using the language you are used to in this context. It is a non-deco course.

As far as the table and fundamentals training goes, the GUE wording would be a bit different though. First, every dive is a deco dive, even if you dive to 10m for 10min. It just happens to be that you efficiently decompress on your way to the surface (and at the surface), without getting into trouble. And, as has been mentioned above, the logic is "begin with the end in mind", and already instill the thinking and discipline required for doing "true" deco dives in the future.

The other thing is, even though the training and table, "does not allow" deco, it does contain a provision for contingencies. That means, if something unexpected happens, say you come across another diver that needs assistance, and through helping him, go over your MDL limit a bit, it's no big deal. There is a procedure, protocol and quantitative method in place, to deal with this emergency. So you don't have the mindset "if I go 1min over I will die" or "fxxx I went over the MDL, what on earth do I do now?".

 

[Ryan Neely]

See its tough to even have a meaningful conversation about this stuff when the base assumptions are so far off from reality.

There ISN'T a no-decompression table for a 180' dive for 30mins. Its not even possible, as a person CAN'T dive to 180ft for that long without signing up for some pretty substantial decompression.

Thanks, @PfcAJ . That's exactly what I needed to hear. I appreciate you taking the time to help me better understand.

 

[elgoog]

Regarding the quoted post, my statement was incomplete so I apologize for that. As @PfcAJ and @CptTightPants21 clarified, it's not 10fpm from the bottom - it's 30fpm to half your max depth (or average depth - the difference is really not that much for a 100ft dive) and then 10fpm from there to the surface. 30fpm is the same recommended ascent rate for pretty much every table and computer. Basically, the difference in the GUE method is that you're spreading out the equivalent of 3min@15ft safety stop as a slow ascent from your first stop depth to the surface. As @blake7 said, you learn the same basic techniques in Fundies/Rec 1 that you would use for all your future training and diving.

@Bob DBF I would disagree with the "deco is deco" in the context of 1min in your statement. Different computers will vary on NDL far more than that. I don't have SSI and PADI NDL tables handy but, IIRC, they don't even have the same number of groups you can end up in after a dive. So, it's very possible that even using those, you would be off by more than a minute in terms of depth and bottom time and still be within NDL (or exceeded it), depending on which table you used.

If you calculate ascents using the GUE method or other methods, your time to surface is almost exactly the same. Let's take the 100ft dive as the example as that's the edge case. Assuming the diver is absolutely perfect in terms of depth and ascent control, the GUE ascent is 6.67min (1.67min from 100ft to 50ft at 30fpm + 5min from 50ft up to surface at 10fpm) and the normal NDL ascent is 5.67min (2.67min from 100ft to 20ft at 30fpm, 3min at 20ft). That's a 1min difference for a perfect diver and I ignored the amount of time it would take in the second method to go from 20ft to the surface. If you go up the last 15-20ft in 1min, we're back to being exactly the same.

 

[taimen]

Deco is deco, at least that was the NDL training I received. Granted 1 minute isn't much but... Naming the table MDL rather than NDL makes my point.

As far as I understood my training is that "minimum deco" table and ascent profile is GUE equivalent to safety stop in recreational diving. Mandatory "deco" or not, that is the only style of ascent they teach for the type of diving. The GUE minimum deco table apparently can include up to 1 minute "mandatory" deco as defined by GF 20/85. But that is their definition of minimum deco ("every dive is a deco dive") and recreational profile. It is not the most aggressive rec table distributed.

 

[tursiops]

As far as I understood my training is that "minimum deco" table and ascent profile is GUE equivalent to safety stop in recreational diving. Mandatory "deco" or not, that is the only style of ascent they teach for the type of diving. The GUE minimum deco table apparently can include up to 1 minute "mandatory" deco as defined by GF 20/85. But that is their definition of minimum deco ("every dive is a deco dive") and recreational profile. It is not the most aggressive rec table distributed.

No, in fact both PADI and NOAA are slightly more aggressive.

 

[Bob DBF]

First, every dive is a deco dive, even if you dive to 10m for 10min.

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

@Bob DBF I would disagree with the "deco is deco" in the context of 1min in your statement. Different computers will vary on NDL far more than that. I don't have SSI and PADI NDL tables handy but, IIRC, they don't even have the same number of groups you can end up in after a dive. So, it's very possible that even using those, you would be off by more than a minute in terms of depth and bottom time and still be within NDL (or exceeded it), depending on which table you used.

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.

As far as I understood my training is that "minimum deco" table and ascent profile is GUE equivalent to safety stop in recreational diving. Mandatory "deco" or not, that is the only style of ascent they teach for the type of diving. The GUE minimum deco table apparently can include up to 1 minute "mandatory" deco as defined by GF 20/85. But that is their definition of minimum deco ("every dive is a deco dive") and recreational profile. It is not the most aggressive rec table distributed.

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

If you calculate ascents using the GUE method or other methods, your time to surface is almost exactly the same. Let's take the 100ft dive as the example as that's the edge case. Assuming the diver is absolutely perfect in terms of depth and ascent control, the GUE ascent is 6.67min (1.67min from 100ft to 50ft at 30fpm + 5min from 50ft up to surface at 10fpm) and the normal NDL ascent is 5.67min (2.67min from 100ft to 20ft at 30fpm, 3min at 20ft). That's a 1min difference for a perfect diver and I ignored the amount of time it would take in the second method to go from 20ft to the surface. If you go up the last 15-20ft in 1min, we're back to being exactly the same.

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