BRW
Contributor
Over-reacting -- not hardly as JW says.
BW
BW
Errors in PADI's/DSAT's Imperial Version of the RDP
- Thread starter Butt Ugly Toad
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Butt Ugly Toad
Registered
Hello All,
Sorry I have not replied before now but the satellite system I am on will not allow me to logon most of the time, plus I had to hop up to Nicaragua for a bit.
First, I would like to clear up some misconceptions that have occurred.
My earlier post, that drew such criticism from BRW, was meant to be humorous and not what BRW deciphered.
Peeps does mean people but the use of this word is not restricted to kids only. I believe it was "coined" on the internet along with many other new terms.
I have been diving with a dive computer for 13 years and was only being humorous once again.
As to the construction of the Tables, I never talked about their construction but only how Table 3 was derived. It only takes looking at how you use the Wheel to figure out how they made Table 3, since the Wheel has no Table 3 and you have to do the math yourself! If you know how to use the Wheel then anyone should be able to see the two errors I have mentioned and how Table 3 came about.
As to the NDL & air consumption rates, just look at the special rules on the back of the RDP to find out what I was referring to? I find it hard to understand why strenuous activities would have any affect on my nitrogen absorption rate unless it has something to do with my breathing rate also, unless it only has to deal with the already absorbed nitrogen being able to get deeper within the diver by the increased blood flow? With labored activities your heart rate is increased, by your brain, in order to carry more oxygen to the cells .... pretty simple. This also creates the need to breathe more to supply the blood with the extra oxygen it requires. With the absorption of more oxygen, I only assumed that there would be a proportional increase in the nitrogen intake, but I guess it is not that simple? I guess that is why I am not a physician ...... my bad!
As to the original intent of this posting, PADI & DSAT are looking into my observations once more but it does not look like there will be any changes. They say that the original creator of the Tables is now dead and no one is left that can ascertain if my observations are correct or not? I find that hard to believe but that is what I was told.
I believe these two groups are in error and since the math is on my side, I will not give up until they are both corrected to correspond with the over 400 other groups (the other 99.5% of the groups).
Respectfully,
Toad
Ps: BRW:
Seven days without diving makes one weak!
Sorry I have not replied before now but the satellite system I am on will not allow me to logon most of the time, plus I had to hop up to Nicaragua for a bit.
First, I would like to clear up some misconceptions that have occurred.
My earlier post, that drew such criticism from BRW, was meant to be humorous and not what BRW deciphered.
Peeps does mean people but the use of this word is not restricted to kids only. I believe it was "coined" on the internet along with many other new terms.
I have been diving with a dive computer for 13 years and was only being humorous once again.
As to the construction of the Tables, I never talked about their construction but only how Table 3 was derived. It only takes looking at how you use the Wheel to figure out how they made Table 3, since the Wheel has no Table 3 and you have to do the math yourself! If you know how to use the Wheel then anyone should be able to see the two errors I have mentioned and how Table 3 came about.
As to the NDL & air consumption rates, just look at the special rules on the back of the RDP to find out what I was referring to? I find it hard to understand why strenuous activities would have any affect on my nitrogen absorption rate unless it has something to do with my breathing rate also, unless it only has to deal with the already absorbed nitrogen being able to get deeper within the diver by the increased blood flow? With labored activities your heart rate is increased, by your brain, in order to carry more oxygen to the cells .... pretty simple. This also creates the need to breathe more to supply the blood with the extra oxygen it requires. With the absorption of more oxygen, I only assumed that there would be a proportional increase in the nitrogen intake, but I guess it is not that simple? I guess that is why I am not a physician ...... my bad!
As to the original intent of this posting, PADI & DSAT are looking into my observations once more but it does not look like there will be any changes. They say that the original creator of the Tables is now dead and no one is left that can ascertain if my observations are correct or not? I find that hard to believe but that is what I was told.
I believe these two groups are in error and since the math is on my side, I will not give up until they are both corrected to correspond with the over 400 other groups (the other 99.5% of the groups).
Respectfully,
Toad
Ps: BRW:
Seven days without diving makes one weak!
Dr Deco
Contributor
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Dear Readers:
GAS UPTAKE
A good question has been raised here as to why activity increases inert gas uptake. An examination of the method of table construction will show you that they are based on No-Decompression Limits and tissue halftimes. These halftimes are chosen by the table designer and do not change under dive conditions. In other words, active or resting, you still have the same 5, 10, 20, 40 . halftime tissues.
COMPARTMENT HALFTIMES
These are the so-called multi-compartment models and are employed to construct all decompression systems today. The only exception of which I am aware is the NASA system, which is a one-compartment model. Because it is employed for decompression to altitude, it comes under the heading of saturation-excursion diving.
The system uses uptake and elimination half times but these are modified by the degree of physical activity (as quantified by oxygen consumption). The system has been developed and tested and is currently used by NASA astronauts during EVA (space walks).
When readers ask about physical activity and the risk of DCS as reflected in gas loads, it is this model that I use when I write the answer. Currently that does not exist any decompression table or meter with this algorithm in it, although I have at times jokingly referred to it as The Bends Buster deco meter. It is only a metaphysical tautology. Some day we might see its reification.
CHNAGES IN LOADS
The changes in blood flow and inert gas loads come about not from the heart rate but rather from opening of capillaries. That is controlled by nerves to he precapillary sphincters (= valves), the accumulations of carbon dioxide, adenosine diphosphate and other metabolic waste products.
Dr Deco :doctor:
[On vacation this week]
GAS UPTAKE
A good question has been raised here as to why activity increases inert gas uptake. An examination of the method of table construction will show you that they are based on No-Decompression Limits and tissue halftimes. These halftimes are chosen by the table designer and do not change under dive conditions. In other words, active or resting, you still have the same 5, 10, 20, 40 . halftime tissues.
COMPARTMENT HALFTIMES
These are the so-called multi-compartment models and are employed to construct all decompression systems today. The only exception of which I am aware is the NASA system, which is a one-compartment model. Because it is employed for decompression to altitude, it comes under the heading of saturation-excursion diving.
The system uses uptake and elimination half times but these are modified by the degree of physical activity (as quantified by oxygen consumption). The system has been developed and tested and is currently used by NASA astronauts during EVA (space walks).
When readers ask about physical activity and the risk of DCS as reflected in gas loads, it is this model that I use when I write the answer. Currently that does not exist any decompression table or meter with this algorithm in it, although I have at times jokingly referred to it as The Bends Buster deco meter. It is only a metaphysical tautology. Some day we might see its reification.
CHNAGES IN LOADS
The changes in blood flow and inert gas loads come about not from the heart rate but rather from opening of capillaries. That is controlled by nerves to he precapillary sphincters (= valves), the accumulations of carbon dioxide, adenosine diphosphate and other metabolic waste products.
Dr Deco :doctor:
[On vacation this week]
blackwater
Guest
Butt Ugly Toad once bubbled...
Hello All,
As to the construction of the Tables, I never talked about their construction but only how Table 3 was derived. It only takes looking at how you use the Wheel to figure out how they made Table 3, since the Wheel has no Table 3 and you have to do the math yourself! If you know how to use the Wheel then anyone should be able to see the two errors I have mentioned and how Table 3 came about.
<snip>
Of course the flat tables pre-date the wheel, so I would guess that the during the design of wheel RER noticed the similarity,and dropped the third table/wheel in favor of simplicity.
I have not issues with the assursoin that RBT + ABT = TBT where TBT is the NDL from table 1, but do not conceed that table 3's RBT times must match table 1's. {I don't say they have to be different, I just haven't been convinced that can't be}
As to the original intent of this posting, PADI & DSAT are looking into my observations once more but it does not look like there will be any changes. They say that the original creator of the Tables is now dead and no one is left that can ascertain if my observations are correct or not? I find that hard to believe but that is what I was told.
having read the "The DSAT Recreatoinal Dive Planner: Development and validation of no-stop decompression procedures for recreational diving" and tried to plugging the M-values listed there into Schnieders equation and only getting "close". It doesn't supprise me that a training organization can not re-engineer the creation of a model that was developed about 20 years ago, with a bit of "rounding" thrown in.
I believe these two groups are in error and since the math is on my side, I will not give up until they are both corrected to correspond with the over 400 other groups (the other 99.5% of the groups).
While you're on this, don't forget that ABT's for 80:Q, 90
, 100:N, 110:L, 120:J&I, 130:G-E; are missing.
Although these can be explained by the time it takes to get to depth at 60ft/Min. For the above depths, the ABT would be reached prior to getting to depth, But if one doesn't account for the models assumption of a slow decent, one might conclude that these were also typo's.
Could it be that your two squares are the result of some non-intuitive artifact of the original derivation of the model?
take care
blackwater.
Hello All,
As to the construction of the Tables, I never talked about their construction but only how Table 3 was derived. It only takes looking at how you use the Wheel to figure out how they made Table 3, since the Wheel has no Table 3 and you have to do the math yourself! If you know how to use the Wheel then anyone should be able to see the two errors I have mentioned and how Table 3 came about.
<snip>
Of course the flat tables pre-date the wheel, so I would guess that the during the design of wheel RER noticed the similarity,and dropped the third table/wheel in favor of simplicity.
I have not issues with the assursoin that RBT + ABT = TBT where TBT is the NDL from table 1, but do not conceed that table 3's RBT times must match table 1's. {I don't say they have to be different, I just haven't been convinced that can't be}
As to the original intent of this posting, PADI & DSAT are looking into my observations once more but it does not look like there will be any changes. They say that the original creator of the Tables is now dead and no one is left that can ascertain if my observations are correct or not? I find that hard to believe but that is what I was told.
having read the "The DSAT Recreatoinal Dive Planner: Development and validation of no-stop decompression procedures for recreational diving" and tried to plugging the M-values listed there into Schnieders equation and only getting "close". It doesn't supprise me that a training organization can not re-engineer the creation of a model that was developed about 20 years ago, with a bit of "rounding" thrown in.
I believe these two groups are in error and since the math is on my side, I will not give up until they are both corrected to correspond with the over 400 other groups (the other 99.5% of the groups).
While you're on this, don't forget that ABT's for 80:Q, 90
, 100:N, 110:L, 120:J&I, 130:G-E; are missing. Although these can be explained by the time it takes to get to depth at 60ft/Min. For the above depths, the ABT would be reached prior to getting to depth, But if one doesn't account for the models assumption of a slow decent, one might conclude that these were also typo's.
Could it be that your two squares are the result of some non-intuitive artifact of the original derivation of the model?
take care
blackwater.
Yes Priate
It does matter as standards stipulate the tables must be taught. In OW Courses.
Socorro Chub
Registered
Hello,
I agree with you in regards to these errors in the PADI Wheel. Especially, when teaching students, accuracy and repeatabiliy are good confidence boosters. During my Divemaster course, I noticed the mistmatch between my wheel and the one portrayed in the manual. While the difference in results might be slight. It just does not feel good not to have the same results as in the manual or the test. It is not very professional and for sure not quite scientific.
The wheel is now discontinued, but for those without a computer or who like to check their computer performance. I recommend using Charlie99 wheel
ScubaBoard Gallery - "Flattened Wheel"
It yields very similar results to the PADI Wheel in most cases. The important thing being that it allows you to estimte the time in each floor of your multilevel dives with decent accuracy and repeatibility. I have ben using this tool for about a year and am quite happy.
Cheers
I agree with you in regards to these errors in the PADI Wheel. Especially, when teaching students, accuracy and repeatabiliy are good confidence boosters. During my Divemaster course, I noticed the mistmatch between my wheel and the one portrayed in the manual. While the difference in results might be slight. It just does not feel good not to have the same results as in the manual or the test. It is not very professional and for sure not quite scientific.
The wheel is now discontinued, but for those without a computer or who like to check their computer performance. I recommend using Charlie99 wheel
ScubaBoard Gallery - "Flattened Wheel"
It yields very similar results to the PADI Wheel in most cases. The important thing being that it allows you to estimte the time in each floor of your multilevel dives with decent accuracy and repeatibility. I have ben using this tool for about a year and am quite happy.
Cheers
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