Question about deco stops when diving with air.

[AndyNZ]

Why is this so difficult for you?

I have roughly 800 dives and have never gone into deco "accidentally".

That's close enough to round up to 1000..... yeah, and if you were signing on for a charter trip you could probably call it 1500.

 

[AndyNZ]

PADI OW does teach no deco diving, and you should have been to take additional training if you want to do that. Since 95% of the population, at least, does not want to do that, the instruction is saved for those that do.

Which to my mind, is not a bad thing.

The OP made a comment that "it was all about greed and everything should be taught in one course".

Well, those courses exist - we offer the GUE Rec 1 course, which goes into a lot more discussion of deco theory than PADI OW.

So here's the choice:

1. PADI OW, 4 dives, two weekends - about $450 from the shop down the road
2. GUE Rec 1, 12 dives, 10 days of training - about $1700


How many people are prepared to pay for that level of training up front???

It seems to me that too many people want top notch training, but also want the instructor to be working for less than the minimum wage whilst doing it. So I'm not sure exactly where the greed is here.......!

 

[Trace Malinowski]

That information was covered on question #2 of Knowledge Review #5 in his academic course work.

It is written on the back of the Recreation Dive Planner that he was issued.

It was a question on the final exam.

John,

Thanks for that.

When I did my open water course decompression lecture was covered over two evenings. We did a lot of work with NDL's, standard air decompression tables, altitude, omitted deco, and special situations. I worked about as many no-deco problems as deco problems in class, at home from the book, and on the paper my instructors gave me which was tricky. On the test, we had about the same number of no-deco questions as deco questions.

PDIC tables use both the US Navy NDL and Standard Air Deco tables.

In the Jeppesen Sport Diver Instructor's Guide which was the test I took in 1983 for my OW cert, questions 88 - 100 deal with tables. Of the 12 questions dealing with tables, decompression diving encompasses 7 questions.

Question 89 - how to perform stage decompression diving
Question 91 - decompression diving fly time vs. no-deco flying time
Question 92 - deep bounce diving & decompression planning
Question 94 - where the diver's chest should be during deco stops
Question 95 - planned deco dive
Question 99 - planned deco dive
Question 100 - 1st dive no deco; repetitive dive planned as deco

As an educator, if you wanted me to remember something important in your class (scuba or otherwise) do you think that 1 question in the knowledge review and 1 on the final is enough? Now that PADI is making tables optional, how many will know the info is on the PADI tables? How many computer divers carry tables? It may be fine, but IMO greater proficiency with tables can't hurt.

I think students need to be more immersed in dive tables and decompression planning than the current educational landscape is providing.

---------------------------------------------------------------------------------

Impulse, if you want to understand tables and deco theory a bit better as it applies to recreational diving, check out a book that is a bit dated, but still an excellent resource called, The Decompression Workbook by George S. Lewbel, Ph.D. Ascent rates are 60 feet per minute (use 30 feet per minute) and some omitted deco and no-fly recommendations have changed, but it will help you really get to the bottom of using Navy tables forward, backward and switching between NDL and decompression planning. Then, you can apply the methods for planning dives to updated tables with greater understanding.

 

[bamamedic]

impulse, why are you so worried about accidental decompression dives?

Sure, it can happen if you aren't paying attention and wind up overstaying your welcome. But, as long as you're paying attention to your depth/time and your dive computer, decompression just won't sneak up on you and bite you like a snake.

Plan your dives, to where you're safely within the amount of time that you know you can stay down without hitting deco, using your computers "planning" mode or the tables you were taught in class.

If for some reason, you accidently hit deco, your computer will give you a "stop depth" and time...for example, 5 min at 20 feet. Ascend to that depth, making sure you don't exceed 30fpm, and wait at that depth until the computer says you're OK to ascend. It might help to hold on to something at that depth, such as a rock or the ascent line, especially if you have issues with buoyancy control. Then ascend slowly once your computer says it's OK, and be prepared to wait 24 hours before getting back into the water (a lot of computers will lockout for awhile). Use that time to constructively think about how you're going to avoid getting into that situation in the future.

Every dive is a decompression dive! During every dive, you absorb nitrogen into your body, and release it on ascent. The only difference between a dive witnin the no-decompression limits, and a dive using planned decompression, is that during an NDL dive, you're usually not absorbing enough nitrogen to make it unsafe to slowly surface at any time, wheras a planned decompression dive involves your absorbing enough nitrogen in your body that it's unsafe to ascend immediately to the surface.

If you want further information on decompression, and what happens to your body under pressure, "Deco for Divers" is an excellent resource. It won't teach you how to plan decompression dives, but it will give you a ton of background information, tell you how the various computer and table algorithms were designed, and hopefully, set your mind at ease.

 

[impulse]

PADI OW does teach no deco diving, and you should have been to take additional training if you want to do that. Since 95% of the population, at least, does not want to do that, the instruction is saved for those that do.

Do you think that 95% of the population is aware of the facts about diving? Most of them see their friend dive and want to become a diver without being aware of what is being happened inside their tissues. How many of them is aware of the functioning of a regulator? How many of them can distiguish a grouper from a lagos ? How many of them know how to free dive? I think free diving is the basics of scuba diving. I have a fairly enough experience about free diving. 95% of the population who want to dive just come up with that diver during a vacation and decide go deep down under the sea. No deco diving is also theorically a wrong expression. It does not mean that if they do not want to do that it must not be thought. Some people does not want to use seatbelts and they want to go fast. So let's remove the seatbelts from those people's cars. IMO, teaching firmly and training a diver about decompression is fairly important. What's wrong about that? You can lear deco rules and still do no deco dives But if you learn no deco dives and go 130fsw when you own a AOW after 8 dives, you are under high risk.

As I said earlier, the PADI course you took did teach you how to deal with emergency decompression using the Recreational Dive Planner you were issued. It was on Knowledge Review #5, which you signed saying that you understood everything on it. It is also printed on the RDP you were given so that you could carry it with you in case you forgot. It was also on your final exam, which you signed saying that any questions you missed were explained to you by your instructor.

Yea, that's right. It did teach me about the Recreational Dive Planner. But how many people sign that with really a firm understanding? Go and ask to a diver who has an AOW about it when you next go diving. I doubt he will be able to answer your questions. I think PADI needs a signature because they are also not confident if their way of teaching "really" teaches something. I did not miss any questions. Because they were exteremely easy. Becasue of my personal interest in the subject, I was able to answer the questions before I take the class. But there were students whe could not answer most of the questions even though they took the class. So what? This is funny.

Like many people, you decided not to use your RDP but elected to use a computer instead. This meant the PADI instruction on the RDP was no longer in operation. You had gone with a new system and a new system's rules.

Where do you know that I do not use the RDP? And more over, if you really think that each and every diver is able to use the RDP instantly after they complete the OW class you must think about that again. And also if people with an OW or AOW certificate must use a RDP, why instructors let them dive without one? Tell the diver throw away their computers and use the RDP. Strange.

When you did, you also elected not to read the computer manual's instructions on how it deals with decompression, so you didn't learn the rules.

You do not understand me. I read the computer manual. But the manual just tell about how the computer operates. I know how it functions, the problem is how reliable are them?

When you dived, you elected not to look at your computer until you were into deco.

If I did not look I would not see we were about to exceed the NDL. Why you always accuse me and not say that, yes decompression rules are important, every diver must learn about that.

So, go ahead and blame PADI because you forgot the instruction you received and elected not to read the instructions on your computer. Since you could not possibly be to blame for anything here, it has to be them, right?

I do not blame anyone or I am not seeking a guilty one. I just am making criticism. Why this bothered you that much?

Which one? There are many theories about decompression diving. There are many different sets of rules and processes. No one class teaches them all.

That must be something the instructer must decide. Not me.

 

[impulse]

impulse, why are you so worried about accidental decompression dives?

Sure, it can happen if you aren't paying attention and wind up overstaying your welcome. But, as long as you're paying attention to your depth/time and your dive computer, decompression just won't sneak up on you and bite you like a snake.

Plan your dives, to where you're safely within the amount of time that you know you can stay down without hitting deco, using your computers "planning" mode or the tables you were taught in class.

If for some reason, you accidently hit deco, your computer will give you a "stop depth" and time...for example, 5 min at 20 feet. Ascend to that depth, making sure you don't exceed 30fpm, and wait at that depth until the computer says you're OK to ascend. It might help to hold on to something at that depth, such as a rock or the ascent line, especially if you have issues with buoyancy control. Then ascend slowly once your computer says it's OK, and be prepared to wait 24 hours before getting back into the water (a lot of computers will lockout for awhile). Use that time to constructively think about how you're going to avoid getting into that situation in the future.

Every dive is a decompression dive! During every dive, you absorb nitrogen into your body, and release it on ascent. The only difference between a dive witnin the no-decompression limits, and a dive using planned decompression, is that during an NDL dive, you're usually not absorbing enough nitrogen to make it unsafe to slowly surface at any time, wheras a planned decompression dive involves your absorbing enough nitrogen in your body that it's unsafe to ascend immediately to the surface.

If you want further information on decompression, and what happens to your body under pressure, "Deco for Divers" is an excellent resource. It won't teach you how to plan decompression dives, but it will give you a ton of background information, tell you how the various computer and table algorithms were designed, and hopefully, set your mind at ease.

Thanks for the info buddy I will order that book from the amazon but it says out of stock. Do you know somewhere else that I can order it?

 

[boulderjohn]

Do you think that 95% of the population is aware of the facts about diving? ..

Not me.

Whew!


OK, thanks for the response. You have told me all I need to know about you and your attitudes and beliefs toward diving. I won't bother you any more. Sorry I offended you earlier. Go on with our life plans.

 

[TSandM]

impulse, with your original post, I gave you credit for being a new diver and having come nose to nose with a situation you weren't well prepared to face, and being frightened by it, and seeking more knowledge.

These things happen to new divers, and yes, I think very few people remember everything they were taught in their class, no matter what class it is. I forgot some things from my Cave 2 class within a few weeks, because I didn't have to use the information. But it wasn't the class's fault.

If you had an imperfect grasp of the material from your OW course, you should have asked more questions, and asked for more problems to work until you felt confident with the material. If you answered the knowledge reviews and the test correctly, and didn't ask any questions, your instructor may not have been able to tell that you were not solid on some topics.

The fact is that there is not much information about executing staged decompression in an OW class, because it isn't needed. Much more time is spent on schooling the diver NOT to enter into decompression. My perception at the beginning was that you had absorbed that warning to the point where you were afraid of deco -- I don't think that's true now.

If you want to be angry about your class or your instructor (and it sounds as though there may have been some questionable judgment about you being on the dive that started this thread) you are welcome to do so. You are also welcome to seek more information (and, btw, Mark Powell has a website, and I bought the book directly from him). But I don't think it's really appropriate to be angry with a class that teaches you NOT to go into deco, and gives you a simple default procedure as to what to do if you do. Deco theory and planning decompression lies outside the scope of an OW class.

 

[bamamedic]

Deco for Divers by Mark Powell

Here's the website

 

[rjack321]

It is not difficult. I just want to understand the real rules. For instance, in the event of a computer mulfunction you may need the underlying understandings. I just do not understand if it's that difficult to properly teach the calculations during the classes. Why it is not needed? Ok questions does not make sense anymore. A class will make sense.

The bottom line:
You are having a hard time adhering to a "no-deco" dive plan,
You are following someone else where you are uncomfortable,
You don't have the awareness to know where you are relative to NDLs when they are right on your wrist.

Thus, everyone here is telling you to (try to) stick to no deco diving. If you slip over NDLs by a few minutes obey the obligation on your computer, pad the shallow stops, try to do better next time. If you have a computer failure and suspect you were close to NDLs, ascend at a controlled rate (20-30ft/min) to roughly 20ft/6m and stay there until you gas supply is low (500psi/35bar) then do a slow ascent to the surface. You will need a decent buddy to help the with the ascent and staying at the ~20ft depth.

As difficult as it might be to accept, you don't have the discipline, maturity, or experience for deco diving. Maybe someday you will but not everyone does or will.

Everyone can choose the people they will be diving with. But it's true that he sometimes is disrespectful.

When he is training the instructor candidates, he gives his nearly empty tank to the candidate and take the candidates scuba equipment. He does this under shallow water. Come on we are not in the military or something. He sometimes provides deco tanks on the boat with regulators going deep down into the sea. Once a diver used that. I never needed to. He has a different kind of approach.

Yeah breaking pretty much every agency standard there is. Find another instructor and another buddy.