Deco without deco training

[Van Isle]

There is a local "crew" where I dive that plans recreational profiles such that they sometimes - and intentionally - end up with 5-15 minutes of "deco" on their Suunto computers.

I have an absolutely infantile understanding of decompression procedures, yet when I "slyly" query them as to their contingencies for OOG, lost gas, over stay, over depth (partly because I am trying to learn) I get blank looks. These guys have no idea what they don't know. Jacket BCs and hog-tied alu80 stages notwithstanding...

If you're talking about unplanned deco, where you over stay your computer or table limits, follow the instructions on the computer or tables. Extra time (gas and conditions permitting) at 20 and 10 feet can't hurt. Read, and re-read NWGrateful Diver's article posted above.

VI

 

[Scared Silly]

BITD (early 80s) when I learned to dive we learned the tables for both no stop and stop diving. Learning the latter was just in case. In the mid 90s when we did planned deco dives but also carried our deco schedules just I like I do today. Today it seems was it taught is that if you exceed the "limits" yer gonna die. At least with the tables folks saw the black "times" and knew to at least a safety stop was mandatory.

As was pointed out certifications/degrees/licenses mean you have successfully passed a test - it does not mean you are qualified or competent to do jack.

 

[TCDiver1]

Heh. "Tables".

I don't even think the plastic dive tables are sold with OW text books anymore. (But for old guys you can still get them online if you want one...)

Not true. For PADI anyway it's still an option.

Also for any of you old farts out there who need a larger table i've got one of those giant RDP's i'd be glad to sell you on the cheap. My brain is too rotted from dive computer use to really need it anymore.

 

[aquaregia]

I have not paid much attention to sport diver training since the 1960s. Are you people saying that the basic Scuba training class does not teach people how to read decompression and repetitive tables? I can understand saving treatment tables for later but basic decom?

My recent NAUI OW covered NDL and RDT, but not deco or reco tables.

 

[Akimbo]

…Really though, it isn't rocket science. Deco is based on nothing more than mathmatical theories that probably will, but may not, work. We are taught that about tables from intitial certification. Though I believe we all should have knowledge of how gas and pressure affects our body, and how stops and gasses work to remove the nitrogen from our body, most deco computers work great these days. I always have at least two and have never been completely let down by a failure. Even with the best tables, or computers, I can still take a hit. Reading and good mentoring is as safe as a cert class. If a class is available, by all means take one. Formal education can't hurt, but this ain't rocket science.

I concur. To be fair, decompression tables were derived from empirical chamber tests in the early 1900s and periodically adjusted as data from the fleet rolled in — all were developed or sponsored by the world's Navies. Air tables were pretty decent by the 1940s but continued to be tweaked as additional data and empirical chamber testing continued. All that data provided a basis for analysis for developing today's decompression tissue theories and algorithms. It is extraordinarily rare that anyone takes a serious hit today without seriously pushing the intended limits of decom guidelines.

There is significant individual variation for decompression that has been incorporated into decompression tables from about 100 years of data. That is why so many people get away with pushing the tables (effectively their computers). However, it is important to remember that these tables evolved based on subjects in relatively excellent physical condition; with the exception of excessive alcohol and caffeine consumption. But even with hangovers; these guys could run for hours, dive all day, and fit into European cut freediving suits. Empirical data based on females, geezers like me, and couch potatoes is virtually absent.

PS: I just re-read this and figured that I better add that the females, geezers, and couch potato comment refers to unconfirmed physiological variables rather than intent to demean.

 

[dbulmer]

Last Sunday my buddy sat his twins on his mask (bifocals) He's got no hope

 

[LeadTurn_SD]

Heh. "Tables".



I think basic OW scuba course equipment requirements now are mask, fins, snorkel, boots, and a computer. Tables are what they sit at when they examine their dive computers...

I don't even think the plastic dive tables are sold with OW text books anymore. (But for old guys you can still get them online if you want one...)

My three kids were certified in 2007 (PADI) and tables were still taught then (at least here in little Hilo). I think I have read that tables were or are being phased out (not sure which agencies).

I was really happy my kids were taught tables; I had decided if tables were not taught, that I would teach them to use tables myself....

Best wishes.

 

[NAM001]

If you are asking about going over the NDL's shown on your computer and acquiring a few minutes of deco obligation then yes ... I did that many times before taking my first deco class.

Most times it was by only a couple minutes, and by the time I got back up to 30 fsw or so the computer was all cleared. Keep in mind that if it's less than 3 minutes, it's basically just a safety stop anyway ... but one you really shouldn't skip.

No, I am NOT advocating it. But what I want to emphasize is that this isn't something you should stress over. It happens. Deal with it calmly, make an orderly ascent, and understand what your computer is telling you.

For more on the subject, see this article ...

... Bob (Grateful Diver)

THANKS FOR THE LINK. after reading so much about ratio deco, I generated a lot of questions and started to believe that to some extent the computer was a bad deal in a deco sit. this has answered it all for me so far. they can and do work together. i am certainly going to read more on my puter in regards to credit for or denied deco dtops and safety stops out side of the stop depth window. i am thinking that evenn if the stops are outside the windows it can be made to work.

thanks again

 

[NAM001]

ignore this

 

[chris1999]

Heh. "Tables".



I think basic OW scuba course equipment requirements now are mask, fins, snorkel, boots, and a computer. Tables are what they sit at when they examine their dive computers...

I don't even think the plastic dive tables are sold with OW text books anymore. (But for old guys you can still get them online if you want one...)

My OW class (NAUI) had tables and a lot of time was spent learning them and planning repetitive dives off them. We weren't taught how to deal with decompression, just told not to exceed NDL limits.