PADI tables finally going away?

[Blackwood]

Spoken like a purist. I am a pragmatist. %99 of the Diving world uses deco to mean "passed the NDL". I'm gonna go with that. But I guess the best way to win an internet argument is to redefine a word to agree with your outlook.

I'm not re-defining 'deco'. I was taught during my very first BOW classroom session that "every dive is a deco dive".

As a new OW student, my brain immediately wanted to reconcile that with the diametrically opposed term No Decompression Limit, which was being used to describe that which I was learning.

What I came to learn is that the term 'NDL' is a standin for "no STOP limit," i.e. the longest I can stay at a given depth on a given gas for which an immediate ascent at the model's AscentRate_MAX provides adequate decompression for a "safe" surfacing ratio.

 

[Tigerman]

I actually did 3 dives on friday where on the last one a guy went into deco (which although he was on air he shouldnt have) diving a profiles none of the other people on the boat that was diving air even came close to deco from. Apparently he had played around with some settings and probably set his computer to "extremely conservative" somehow..

 

[boulderjohn]

I actually did 3 dives on friday where on the last one a guy went into deco (which although he was on air he shouldnt have) diving a profiles none of the other people on the boat that was diving air even came close to deco from. Apparently he had played around with some settings and probably set his computer to "extremely conservative" somehow..

It's easy to do. If you are diving a Suunto, you are already very conservative. If you set the personal fitness setting (for example) up a notch, you will get even more conservative.

So what if he were diving a PADI table and went into deco (passed NDL's) by one minute? He would have had to do an 8 minute safety stop and then stay out of the water for 6 hours. Why? Because the table has nothing in it for figuring decompression stops, so it automatically puts you into an extreme position. Go into deco by 5 minutes and you have a 15 minute safety stop (if possible) followed by 24 hours out of the water.

So what would happen in either case with that conservative computer? In the one minute case, there would be a warning and an extended safety stop. Maybe. It often clears out by the end of a normal safety stop. In the 5 minute case, there might be a ceiling requiring a brief deeper stop followed by a longer safety stop. You would also be required to have longer surface intervals before the next dives, but nothing like 6 hours.

 

[rstofer]

In the case of, say, a 60' dive on EAN32 using the NAUI 1997 tables, if the diver overstayed the 100 minute NDL by, say, 80 minutes, he could look at the table and see he needs to hang at 10' for 29 minutes.

Pretty extreme but if he only overstayed by 40 minutes, he could get by with a 10 minute stop.

The NAUI tables have it covered if only I had reading glasses under water. I wonder if those glue-on lenses really work?

Richard

 

[Puffer Fish]

It's easy to do. If you are diving a Suunto, you are already very conservative. If you set the personal fitness setting (for example) up a notch, you will get even more conservative.

So what if he were diving a PADI table and went into deco (passed NDL's) by one minute? He would have had to do an 8 minute safety stop and then stay out of the water for 6 hours. Why? Because the table has nothing in it for figuring decompression stops, so it automatically puts you into an extreme position. Go into deco by 5 minutes and you have a 15 minute safety stop (if possible) followed by 24 hours out of the water.

So what would happen in either case with that conservative computer? In the one minute case, there would be a warning and an extended safety stop. Maybe. It often clears out by the end of a normal safety stop. In the 5 minute case, there might be a ceiling requiring a brief deeper stop followed by a longer safety stop. You would also be required to have longer surface intervals before the next dives, but nothing like 6 hours.

Excellent point, and my computer will throw up it's hands and give up after a dive over over 6 hours at 100 ft... something I would find difficult to do on one tank, several tanks or anything I could possibly carry.

 

[ScubaSteve]

Excellent point, and my computer will throw up it's hands and give up after a dive over over 6 hours at 100 ft... something I would find difficult to do on one tank, several tanks or anything I could possibly carry.

You seemed to have forgotten about repetitive dives. Granted the first dive might take you a long time to go into deco at 100' but on the 10th of a series.....probably not so much time required.

 

[boulderjohn]

You seemed to have forgotten about repetitive dives. Granted the first dive might take you a long time to go into deco at 100' but on the 10th of a series.....probably not so much time required.

Could you expand or rephrase? I don't understand this point.

 

[ScubaSteve]

Excellent point, and my computer will throw up it's hands and give up after a dive over over 6 hours at 100 ft... something I would find difficult to do on one tank, several tanks or anything I could possibly carry.

You seemed to have forgotten about repetitive dives. Granted the first dive might take you a long time to go into deco at 100' but on the 10th of a series.....probably not so much time required.

Could you expand or rephrase? I don't understand this point.

Certainly. The way that I read Puffer Fish's response was to say that one tank was not sufficient air to last them into a deco stop (right wrong or indifferent to me). This is why I said it was easy to go into deco on repetitive dives....(example - nice safe profiles in Coz, average 3 tanks a day on air had me pushing the NDL limits on my Suunto after 3 days). The first dive was nowhere near any sort of deco stop because my air was gone before I got to that point.....thus my poorly worded statement above.

 

[boulderjohn]

Certainly. The way that I read Puffer Fish's response was to say that one tank was not sufficient air to last them into a deco stop (right wrong or indifferent to me). This is why I said it was easy to go into deco on repetitive dives....(example - nice safe profiles in Coz, average 3 tanks a day on air had me pushing the NDL limits on my Suunto after 3 days). The first dive was nowhere near any sort of deco stop because my air was gone before I got to that point.....thus my poorly worded statement above.

I believe you misread his post. Here's how I read it.

He said "after a dive over over 6 hours at 100 ft... something I would find difficult to do on one tank, several tanks or anything I could possibly carry."

He is not talking about going into deco. With the PADI tables, the diver went into deco 5 hours and 40 minutes before that point.

He is referring to an earlier post in which it was asserted that computers abandon you if you violate deco limits. He is saying that his computer abandons him 5 hours and 40 minutes after violating deco limits, something that is never going to happen.

 

[ScubaSteve]

I definitely misread it then.