I wanted to park the thread until I had a chance to think about it. Now that I have though about it... I can't find it
seriously... it is there but I haven't be able to restore it... yet.
Does not compute but should I ?
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seriously... it is there but I haven't be able to restore it... yet.
ScubaDan
Guest
Only a regulator can pull a thread, I can't pull my own threads, I can't even delet a post I make to a thread.
landlocked
Contributor
We (my dive buddy and I) were hoping to be able to spend our computer money on a DIR-F class this summer. We were under the impression that after DIR-F we may not want a computer any longer or, at least not for the same reasons. Unfortunately, Pug parked the "Thread" before I was able to read it. I think it may have greatly influenced our decision. (I greatly hope that I am smart enough to never attempt a dive based soley on something I read on the Internet!) Now O-ring jumps in with the above quote. I assume that is a little literal double talk which means that they didn't use a little printed card or wheel? I assume that they did teach N2 loading and how to tell when it is time to get out of the water? Personally, SeaJay, Mike F. and Pug, I love ya all and appreciate what each of you is trying to say.
Um... so Pug, when you find the lost thread, would you be willing to let me have a peek? I am currious to see how close it is to what the NetDoc sent me some time back. Pretty please. I promise I will never tell a living soul. Well maybe I could discuss it with my dive buddy?
Maybe my class was especially bad and we all failed so miserably that we didn't make it that far (we also didn't do any liftbags). Anyway, for whatever reason, that was not covered. I don't know if this is something new that they do or if my DIRF was just special.. I REALLY hope they cover this type of stuff in my Cave 1 class though...I would love to learn it straight from the horse's mouth..landlocked once bubbled...
We (my dive buddy and I) were hoping to be able to spend our computer money on a DIR-F class this summer. We were under the impression that after DIR-F we may not want a computer any longer or, at least not for the same reasons. Unfortunately, Pug parked the "Thread" before I was able to read it. I think it may have greatly influenced our decision. (I greatly hope that I am smart enough to never attempt a dive based soley on something I read on the Internet!) Now O-ring jumps in with the above quote. I assume that is a little literal double talk which means that they didn't use a little printed card or wheel? I assume that they did teach N2 loading and how to tell when it is time to get out of the water? Personally, SeaJay, Mike F. and Pug, I love ya all and appreciate what each of you is trying to say.
Um... so Pug, when you find the lost thread, would you be willing to let me have a peek? I am currious to see how close it is to what the NetDoc sent me some time back. Pretty please. I promise I will never tell a living soul. Well maybe I could discuss it with my dive buddy?
JeffG
Contributor
I see that GUE has put the DIR-F New Workbook
for sale on their web site. Does this/Would it contain the "on the fly" deco calc?
for sale on their web site. Does this/Would it contain the "on the fly" deco calc?
I doubt it. I have the cave and tech manuals and don't remember seeing it anywhere in those. I'll get one and look though.
I am re-reading cave for my upcoming class now and haven't seen it in there yet..
UP suggested that I post how I do it and I said Id post some stuff. Im not sure that just talking about what I do will be all that interesting so lets something else. Ok? Some deco talk fo fun
Some background
I think we are all taught to use the tables the same way regardless of which tables we use. Were taught to calculate a square profile using our maximum depth for the dive. Most tables that I have used specify this method explicitly in the directions for use. The exception here is the PADI/DSAT wheel, which was designed for multilevel use but few actually use it so lets leave it out for the most part. Some of the tables we use were tested and some even using Doppler bubble detection. What this tells us is that within the conditions of the test we should be in good shape when using these models. Another important thing to note is that we also know that the mathematical model the tables are based on are tools we use to predict our status and dont directly represent what goes on in the body. We are also cautioned to be extra conservative when doing multiple dives over multiple days. It stands to reason that the further out we go the less we feel we can rely on the model to predict what will happen to our boddy. I also think most will agree that there are many things that the models just dont account for.
The Multilevel problem and some questions
Divers realize that they dont always spend their entire dive at the maximum depth. Back before computers Ill bet this seemed like a real problem. There were, though, other methods. I dont know if they were taught or if divers just started using them. A post by BRW says the old NAUI tables were multilevel and when used to calculate ever shallower levels never exceeded any M value (in computer testing). Divers used the same method with other tables. The method which Dr. Deco has called reading the tables sideways was essentially treating each new level as a rep dive with a surface interval of zero. I dont think the DSAT/RDP was ever tested using this method but Dr. Deco has stated that in most cases it will work. I think the term will work is defined as keeping all compartments at or below their M value. I think there are some obvious problems with using this method. In order to calculate the dive on the fly you would need to carry a set of tables on the dive. It would also require some fairly complex and error prone table calculations. Early in my diving I heard of divers using average depth to calculate their dive. I thought they were just suffering from a misunderstanding of how the math in the model is being done. Think about it, a gas absorption model tracks multiple compartments with different half times and different M values. Therefore we would have to apply some calculus to choose a depth (from a multilevel profile) that would be the square profile equivalent. I think it would be the average area under a range of functions. How close will using average depth get us? After all we said that our tables dont necessarily depict what is actually going on in our body. Will it work? What about multiple dives over multiple days? I dont intend to answer those questions because I dont have the answer. I certainly dont have an answer that has been tested over a range of profiles with a representative cross section of the diving population.
Some personal experience
Last summer while in Florida doing some cave diving I met a diver who is a PADI instructor and has both NSS-CDS (I think, or it may have been NACD) and GUE cave training. We were both at a 4th of July cook out (I think it was). Anyway I had to ask if I could bend his ear with some questions about profiling. He was the first of two GUE trained divers that I have had the opportunity to discuss the subject with. Both gave similar answers. Keep in mind I am not trying to speak for these divers or GUE and I may have everything backwards. My only intent is to relay the points that I walked away with. I of course pointed out that using average depth isnt mathematically valid. He promptly agreed but pointed out that decompression wasnt exactly an exact science. Ok, now were getting somewhere. I questioned the choice of an average depth. His response was use a deeper depth if it makes you feel better. I basically asked how one would know what they should feel better about using. If I remember, his answer was experience. He then used the dive he had done that afternoon as an example. The dive had a max depth of like 100 ft however, the vast majority of the time was spent above 60 ft. If I remember right they decompressed based on an 80 ft dive for whatever the bottom time was. Maybe 80 is the mean of 60 and 100 but keep in mind that far more time was spent above 60 so a weighted average would be shallower than 80 ft. His validation that his profile was acceptable was the fact that he and his buddy felt great after the dive, something else to think about? Would this work as well doing 3 5 dives per day on a 7 day Caribbean vacation?
Some more personal experience
I have learned and recommend to others that its a good idea to increase depth and time gradually when doing staged decompression dives. The reason is that no matter what model or method you use for your calculations there are no guarantees. Since I believe its possible to get a little bent I figure that if I pay attention to how I feel before, during and after the dive I may notice if I dont feel as good as I think I should after a dive. If that happens maybe I should change something. It might be something in my preparation for the dive or it may be the profile. The decompression software I use has some user adjustable parameters. Changing those parameters has a dramatic effect on the profile generated. Which is the correct setting? Which is the real profile? Maybe a more appropriate question is for whom or under what conditions?
Conclusions
When you first start diving calculating decompression is rather easy. You just use the tables you are given and calculate a square profile as directed. Once certified, (or before) you have the option of using a computer to take advantage of a multilevel profile or sticking with your tables. But wait; there is still a wide variety of computers using different models and different tables also using different models. The different options will present different limits in NDL and required surface intervals. Later if you begin to do more technical dives you are faced with choosing from a plethora of computers, models and user settable parameters within those computers and software. Here there can really be a dramatic difference in the profiles calculated. Which do you use and why? Many of these choices have little testing behind them at best. Among other things you will need to be aware of the profile you dive and how you feel. This might give some ideas for good uses for a logbook besides just counting dives. After reading this long-winded post Im sure you noticed that I didnt really give any answers. I agree, but I sure asked a lot of questions.
Some background
I think we are all taught to use the tables the same way regardless of which tables we use. Were taught to calculate a square profile using our maximum depth for the dive. Most tables that I have used specify this method explicitly in the directions for use. The exception here is the PADI/DSAT wheel, which was designed for multilevel use but few actually use it so lets leave it out for the most part. Some of the tables we use were tested and some even using Doppler bubble detection. What this tells us is that within the conditions of the test we should be in good shape when using these models. Another important thing to note is that we also know that the mathematical model the tables are based on are tools we use to predict our status and dont directly represent what goes on in the body. We are also cautioned to be extra conservative when doing multiple dives over multiple days. It stands to reason that the further out we go the less we feel we can rely on the model to predict what will happen to our boddy. I also think most will agree that there are many things that the models just dont account for.
The Multilevel problem and some questions
Divers realize that they dont always spend their entire dive at the maximum depth. Back before computers Ill bet this seemed like a real problem. There were, though, other methods. I dont know if they were taught or if divers just started using them. A post by BRW says the old NAUI tables were multilevel and when used to calculate ever shallower levels never exceeded any M value (in computer testing). Divers used the same method with other tables. The method which Dr. Deco has called reading the tables sideways was essentially treating each new level as a rep dive with a surface interval of zero. I dont think the DSAT/RDP was ever tested using this method but Dr. Deco has stated that in most cases it will work. I think the term will work is defined as keeping all compartments at or below their M value. I think there are some obvious problems with using this method. In order to calculate the dive on the fly you would need to carry a set of tables on the dive. It would also require some fairly complex and error prone table calculations. Early in my diving I heard of divers using average depth to calculate their dive. I thought they were just suffering from a misunderstanding of how the math in the model is being done. Think about it, a gas absorption model tracks multiple compartments with different half times and different M values. Therefore we would have to apply some calculus to choose a depth (from a multilevel profile) that would be the square profile equivalent. I think it would be the average area under a range of functions. How close will using average depth get us? After all we said that our tables dont necessarily depict what is actually going on in our body. Will it work? What about multiple dives over multiple days? I dont intend to answer those questions because I dont have the answer. I certainly dont have an answer that has been tested over a range of profiles with a representative cross section of the diving population.
Some personal experience
Last summer while in Florida doing some cave diving I met a diver who is a PADI instructor and has both NSS-CDS (I think, or it may have been NACD) and GUE cave training. We were both at a 4th of July cook out (I think it was). Anyway I had to ask if I could bend his ear with some questions about profiling. He was the first of two GUE trained divers that I have had the opportunity to discuss the subject with. Both gave similar answers. Keep in mind I am not trying to speak for these divers or GUE and I may have everything backwards. My only intent is to relay the points that I walked away with. I of course pointed out that using average depth isnt mathematically valid. He promptly agreed but pointed out that decompression wasnt exactly an exact science. Ok, now were getting somewhere. I questioned the choice of an average depth. His response was use a deeper depth if it makes you feel better. I basically asked how one would know what they should feel better about using. If I remember, his answer was experience. He then used the dive he had done that afternoon as an example. The dive had a max depth of like 100 ft however, the vast majority of the time was spent above 60 ft. If I remember right they decompressed based on an 80 ft dive for whatever the bottom time was. Maybe 80 is the mean of 60 and 100 but keep in mind that far more time was spent above 60 so a weighted average would be shallower than 80 ft. His validation that his profile was acceptable was the fact that he and his buddy felt great after the dive, something else to think about? Would this work as well doing 3 5 dives per day on a 7 day Caribbean vacation?
Some more personal experience
I have learned and recommend to others that its a good idea to increase depth and time gradually when doing staged decompression dives. The reason is that no matter what model or method you use for your calculations there are no guarantees. Since I believe its possible to get a little bent I figure that if I pay attention to how I feel before, during and after the dive I may notice if I dont feel as good as I think I should after a dive. If that happens maybe I should change something. It might be something in my preparation for the dive or it may be the profile. The decompression software I use has some user adjustable parameters. Changing those parameters has a dramatic effect on the profile generated. Which is the correct setting? Which is the real profile? Maybe a more appropriate question is for whom or under what conditions?
Conclusions
When you first start diving calculating decompression is rather easy. You just use the tables you are given and calculate a square profile as directed. Once certified, (or before) you have the option of using a computer to take advantage of a multilevel profile or sticking with your tables. But wait; there is still a wide variety of computers using different models and different tables also using different models. The different options will present different limits in NDL and required surface intervals. Later if you begin to do more technical dives you are faced with choosing from a plethora of computers, models and user settable parameters within those computers and software. Here there can really be a dramatic difference in the profiles calculated. Which do you use and why? Many of these choices have little testing behind them at best. Among other things you will need to be aware of the profile you dive and how you feel. This might give some ideas for good uses for a logbook besides just counting dives. After reading this long-winded post Im sure you noticed that I didnt really give any answers. I agree, but I sure asked a lot of questions.
SeaJay
Contributor
Okay, a real quick note here...
In my experience, DIR-F did not teach deco theory. (My experience was the same as O-ring's.) Furthermore, I am not qualified to talk about deco theory. I am not yet a deco diver, and all that I know about the subject is what I've learned on my own accord by going and seeking the information myself. Until I receive that training, though, I refuse to dive with a deco obligation.
What I do know, and have resisted sharing, is the simple technique to calculate your No Decompression Limit "on the fly." Since most manufacturers of computers (even those capable of calculating deco) recommend staying within NDL's, then it hardly seems money well-spent to purchase a computer designed mostly to simply keep you out of a mandatory deco obligation... When that's simple to calculate "on the fly" by yourself, even on a multilevel dive.
I'm not sure how it came to be the opinion of the board here that I am not sharing deco theory. Perhaps I led y'all to believe that. That is not what I meant at all.
What I don't feel comfortable sharing is the "on the fly" method of calculating your NDL... In effect, having a table permenantly embedded in your brain, such that a computer seems pointless.
And it's not that you need "the secret handshake," it's that the system involves more than the simple knowlege of the math. It involves a whole mindset change, and substantial changes in dive style (or even lifestyle). And those things can't be taught over the Internet. They have to be taught with practice.
That's why I recommend that people take the DIR-F course if they want to know the procedure. It's no big magic... Just a simple rule that gets you a fair degree of accuracy with some math simple enough to do in your head.
In my experience, DIR-F did not teach deco theory. (My experience was the same as O-ring's.) Furthermore, I am not qualified to talk about deco theory. I am not yet a deco diver, and all that I know about the subject is what I've learned on my own accord by going and seeking the information myself. Until I receive that training, though, I refuse to dive with a deco obligation.
What I do know, and have resisted sharing, is the simple technique to calculate your No Decompression Limit "on the fly." Since most manufacturers of computers (even those capable of calculating deco) recommend staying within NDL's, then it hardly seems money well-spent to purchase a computer designed mostly to simply keep you out of a mandatory deco obligation... When that's simple to calculate "on the fly" by yourself, even on a multilevel dive.
I'm not sure how it came to be the opinion of the board here that I am not sharing deco theory. Perhaps I led y'all to believe that. That is not what I meant at all.
What I don't feel comfortable sharing is the "on the fly" method of calculating your NDL... In effect, having a table permenantly embedded in your brain, such that a computer seems pointless.
And it's not that you need "the secret handshake," it's that the system involves more than the simple knowlege of the math. It involves a whole mindset change, and substantial changes in dive style (or even lifestyle). And those things can't be taught over the Internet. They have to be taught with practice.
That's why I recommend that people take the DIR-F course if they want to know the procedure. It's no big magic... Just a simple rule that gets you a fair degree of accuracy with some math simple enough to do in your head.
landlocked
Contributor
It is probably the best way, but it is so subjective. I dive with tables, strictly NDL. But I also try and pay close attention to how I feel after a dive. As a result, I now make sure that I am well hydrated, well rested, use Nitrox whenever possible and eat well before and after diving. But doesn't this thinking lead to getting bent at least once. How do you find your limit if you never get bent? I would like that limit to be set some other way than finding out that I don't feel well "after" a dive.
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