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

[PfcAJ]

I might be wrong, but I think what @EFX is asking is:

If he planned a dive to 180 ft for 30 minutes, a chart for no-decompression limits is going to give one set or readings.

What if that planned dive became more of a multi-level dive where he spent 5 minutes at 180 ft., 10 minutes at 90 ft., and 15 minutes at 45 ft. (or something similar) so that his average depth ends up being 90 ft.

Since it has been suggested that the GUE tables run off an average depth, or that using average depth as a means of calculating no-decompression is perfectly valid, how do these two dive profiles compare? According the graph above, using the average depth of 90 feet for 30 minutes makes you a "G" diver. Surely that isn't the same for the original planned dive.

For what it's worth, if @EFX isn't asking the question, I am. Using an average depth doesn't make a lot of sense. It almost feels like reverting to the old Dive Wheel would be more accurate ... but I'm new so I don't really know anything.

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.

 

[tursiops]

It's a table. The depths are listed in the first column.

What does "depth" mean? Max or Average?

 

[seeker242]

What does "depth" mean? Max or Average?

Same as any other table usage, max depth. Although, GUE Rec 1 does teach depth averaging to compensate for strict tables being overly conservative.

 

[Bob DBF]

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

It IS an NDL table - officially, MDL (no deco beyond the 1min every 10ft during ascent)

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

 

[blake7]

It is NDL diving, check the depths and times with your favorite computer.

The reason it is called MDL is that 1 min per 10ft is just the standard GUE deco ascent speed. So, in the spirit of "starting with the end in mind..." they teach even a newbie OW diver that ascent speed control and stability are important and they should practice it from the beginning. This is also why a GUE Rec 1 diver will always know what their minimum gas is, so that there really is no situation where they would have to do something like a CESA, but would just do a normal MDL ascent sharing gas with their buddy.

 

[CptTightPants21]

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

You are getting confused by the names. It is a NDL table/dive. GUE teaches a steady ascent of 10ft a min for none deco dives (30 sec stop, 30 second slide) instead of the 3 min safety stop.

All my diving has been doubles and deco, so I have no real world experience if divers are taking single tanks at 100 and taking 10 min to ascent vs the 6 min that would be the normal convention with safety stop. Most of the time I have seen it used in quarry or Mexican cave, a no deco dive ends up at the platforms or wall or at the entrance and the team ascends 1 min per 10 ft from 30ft instead of stopping at 15' and waiting for 3 min.

 

[PfcAJ]

You are getting confused by the names. It is a NDL table/dive. GUE teaches a steady ascent of 10ft a min for none deco dives (30 sec stop, 30 second slide) instead of the 3 min safety stop.

All my diving has been doubles and deco, so I have no real world experience if divers are taking single tanks at 100 and taking 10 min to ascent vs the 6 min that would be the normal convention with safety stop. Most of the time I have seen it used in quarry or Mexican cave, a no deco dive ends up at the platforms or wall or at the entrance and the team ascends 1 min per 10 ft from 30ft instead of stopping at 15' and waiting for 3 min.

10fpm is ONLY in the shallow part of the ascent, not from the bottom.

30fpm off the bottom.

 

[CptTightPants21]

10fpm is ONLY in the shallow part of the ascent, not from the bottom.

30fpm off the bottom.

You are 100% correct. It has been so long I forgot. 30ft ascent rate to half depth (i think this is half max depth) and then 10ft per min.

What this would mean for a 100ft dive is 2 min to go from 100 to 50, then 1 min every ten feet to the surface. So 7 min ascent vs the 6 min ascent using the 3 min safety stop method.

 

[dmaziuk]

But still quite a bit faster

In my job, an advanced computer program is often the right tool for the job, but sometimes the right tool is a pen and a pad of paper.

... but only if you have the expertise to rut the back-of-the-envelope guesstimate. Brain's learning computer, if yours isn't trained on the job in question, spend the time with advanced computer program instead.

 

[Bob DBF]

You are getting confused by the names. It is a NDL table/dive. GUE teaches a steady ascent of 10ft a min for none deco dives (30 sec stop, 30 second slide) instead of the 3 min safety stop.

It IS an NDL table - officially, MDL (no deco beyond the 1min every 10ft during ascent)

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