Light deco?

[scubadada]

Diver 1 runs their dive computer pure DSAT.
Diver 2 runs their computer RGBM with SF 2 setting

Both divers dive together and do the exact same dive. Diver 1 never gets close to his NDL.
Diver 2 racks up 5 minutes of deco time. Both divers do the same ascent and safety stop. By the end of the safety stop diver 2’s deco has cleared.

Both divers did identical dives. So which diver was the deco diver?

The definition for deco must be simple and easy for practical use. If you exceed the NDL for your computer and for your settings, you are in deco and should satisfy your obligation before surfacing. If you do not, for most computers, you will be locked out in violation gauge mode. If you do not like the NDLs for your computer, you can adjust the personal factors or dive a computer that is more liberal in its deco algorithm.

Several responders to this thread have described light deco as exceeding NDL with a conservative computer, knowing well that this would not be exceeding NDL with a more liberal algorithm. This is well beyond the knowledge and experience of the majority of divers. I dive very frequently in SE Florida. Not uncommonly, I'm asked by a diver on the boat why their computer does not seem to be working correctly. A frequent response is that you missed a deco stop and are in violation gauge mode. They generally look at me like I am an alien.

 

[boulderjohn]

Have you tried running that by PADI? I'm referring specifically to the grey cells on the "no deco" RDP where it says "safety stop shall be required" (emphasis mine).

I don't think that has been mentioned on ScubaBoard more than 1,000 times over the years. To start with, whatever language PADI uses in this specific case has nothing to do with the language most people use in their everyday diving.

When they made those tables, PADI was in a difficult situation with the language. They made what they called a no decompression table, meaning that you could not do what they considered to be a decompression dive and still use the table. That is why you have to wait 6 hours before going back into the water for a mere 1 minute of mandatory decompression--the table washes out in 6 hours, and you have no way to find a spot on it before then. They added a suggestion to do safety stops to be extra safe, which was then a pretty new idea. When dives got close to a required decompression stop (but not quite there), they wanted to go beyond a suggestion for a safety stop, but lacked the language to show that it was almost a decompression stop that would take you off the tables. Yes, it is confusing. I am sure they would welcome your suggestion for better language. (Actually, maybe not, since they realize the idea of tables in general is nearly obsolete.)

Because of this confusion, PADI has stopped calling those dives no decompression dives--they are now no stop dives. Of course, the problem you cite is still there.

 

[boulderjohn]

Then riddle me this - how do you answer the question without saying both and none?

You simply say that the divers need to understand what is happening with the different algorithms and not get hung up on the meaningless definition of the terms, which is essentially what several other people have already said already. The correct answer is "who cares?"

 

[dmaziuk]

Because of this confusion, PADI has stopped calling those dives no decompression dives--they are now no stop dives.

Then the poll applies to tech divers only and should be moved to tech forum. Or perhaps ask for definition of "light stop".

 

[scubadada]

Then the poll applies to tech divers only and should be moved to tech forum. Or perhaps ask for definition of "light stop".

Again, you are incorrect. I would imagine a fair percentage of experienced rec divers do light deco. Thus, the rationale for the post.

 

[boulderjohn]

Then the poll applies to tech divers only and should be moved to tech forum. Or perhaps ask for definition of "light stop".

I think you are missing my point about the vagueness of the language. I also think this is in the appropriate forum. As I said earlier, I ran into a diver with no technical training who routinely did 10 minutes of deco with no redundant gas. I think it is good for people to know that, whatever you call that practice, it has its issues.

 

[npole]

Again, you are incorrect. I would imagine a fair percentage of experienced rec divers do light deco. Thus, the rationale for the post.

I confirm, when i'm in Italy, were we dive, a good 80% of our NO TEC dives will end with few minutes of deco stops, especially if you're at your second (or third) dive. This is due to the conformation of our dive sites, where (not all, but most) are beyond 30 meters and it's really limiting yourself staying withing the NDL for the whole length of the dive. You won't have OW doing this, but for most of the AOWD with good experience it's a common practice (whenever the doctrine says it's not).
We must be realistic, it's not a taboo, it happens every time.

 

[scubadada]

thanks @npole, I believe this is common everywhere. In general, people just do not talk about it, somewhat of a taboo.

 

[Basking Ridge Diver]

Does that help?

Must have missed the memo... Answer is Who Cares... lol

Anyway I guess some folks have strong opinions on this one...

 

[dmaziuk]

Must have missed the memo... Answer is Who Cares... lol

Anyway I guess some folks have strong opinions on this one...

Apparently some folks dive with twin HP 120s in order to never go into "light deco"... the world is full of wonders.