I'd be glad to help, but my name is worse than mud in that location. My support would probably do mire harm than good.
Errors in PADI's/DSAT's Imperial Version of the RDP
- Thread starter Butt Ugly Toad
- Start date
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The Pirate
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With all due respect Mr. Butt Ugly Toad (and BTW, that's a great name you have); what difference does it make. Do you actually use those tables? By now you should have done enough dives to know that you can go to any recreational dive location and using the standard al 80's, dive 4 or more dives a day to any rec depth with a nice slow ascent, a 5 min safety stop at 20', toast the bottle, do a respectable surface interval, keep getting back in with a full btl and never get bent. So what do you need the tables for anyway? What would you rather do on your surface interval; bury your nose in PADI's RDP trying to figure out your pressure group or scope the beach for babes?
The Pirate
The Pirate
Dr Deco
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"Tables? We don't need no stinkin tables."
Re: comment from Pirate above - - With due respect to the "Treasure of the Sierra Madre":bonk:
Re: comment from Pirate above - - With due respect to the "Treasure of the Sierra Madre":bonk:
Scuba
Contributor
Dr. Deco has said in other posts it is good to "scope the beach for babes" - and then some, to help with decompression. (JOKE)
Don't mean to put words in your mouth Doc.
Don't mean to put words in your mouth Doc.
blackwater
Guest
from the pragmatic point of view, yes I agree the time is better spent scoping for babes, but I also think that we should know the answer to the original question. I'm not sure if the table is in error, and haven't had time to check it out to give a better answer, but shooting from the hip, I have the following thoughts to add to the discussion:
1) I think the two table method is a short cut that was discovered because table 3 (it's the exponential offgassing of the 60 minute comp)is so similar to the other tables (worst case of compartments exponential ongassing), but that doesn't mean that it should be exactly the same.
2) As I read the RDP paper, the dive times are calculated on a trapizoidal profile, a decent,and then a bottom time. I presume the surface interval is a rectangular profile (i.e. a single segment at depth 0 fsw). The decent portion is pretty short, so it has a small impact on the total dive time. (as were getting picky, any guesses as to how the accent time is handled? it's not part of the dive, but it's not part of the surface interval)
This could explain why those two values are different. if you look at the 60 fsw line at around 35 minutes, you can see that the boxes differ by 2 minutes on either side. so minor variations would still place the value at 35, while the 70 fsw box in question is between 33 & 36, so that one calculation rounds to 34 while the other rounds to 35 is not necessarily wrong.
I would like to run the numbers, but haven't had time (just moved, and have a lot of unpacking/painting/etc to do).
I hope this gives you some food for thought.
thanks
GT
1) I think the two table method is a short cut that was discovered because table 3 (it's the exponential offgassing of the 60 minute comp)is so similar to the other tables (worst case of compartments exponential ongassing), but that doesn't mean that it should be exactly the same.
2) As I read the RDP paper, the dive times are calculated on a trapizoidal profile, a decent,and then a bottom time. I presume the surface interval is a rectangular profile (i.e. a single segment at depth 0 fsw). The decent portion is pretty short, so it has a small impact on the total dive time. (as were getting picky, any guesses as to how the accent time is handled? it's not part of the dive, but it's not part of the surface interval)
This could explain why those two values are different. if you look at the 60 fsw line at around 35 minutes, you can see that the boxes differ by 2 minutes on either side. so minor variations would still place the value at 35, while the 70 fsw box in question is between 33 & 36, so that one calculation rounds to 34 while the other rounds to 35 is not necessarily wrong.
I would like to run the numbers, but haven't had time (just moved, and have a lot of unpacking/painting/etc to do).
I hope this gives you some food for thought.
thanks
GT
OP
Butt Ugly Toad
Registered
It is amazing what peeps think about the RDP? As to some of the questions that have popped-up, here are my replies:
Do I use the RDP?
NO! I have a fancy lil thingy called a Dive Computer and I no longer use the RDP personally. However, I am an Instructor and must teach new peeps the ins-and-outs of the RDP for them to successfully complete their Open Water Certification.
Table 1-2 shortcut?
Table 1 is where Table 3 comes from. The Wheel Version of the RDP matches Table 1 perfectly and shows the errors of Table 3. Look at the way you find your "Adjusted No-Decompression Limit" using the Wheel Version and you will find it is just the Table 1 - 2 method I have described for the Table Version. There is no Table 3 on the Wheel Version ... you have to figure it out doing that dreaded math thingy!
Babes?
I find that babe searching is always a good surface interval activity, as long as you don't ascend too fast to check-out the babes awaiting you at the surface. I guess patience is more than a virtue?
As to what the Pirate said in his posting:
My air consumption rate (ACR) allows me to exceed the NDL for any depth beyond 70 feet, so what you propose would not be wise in my case. I posted another question concerning ACR & the NDL, and it seems they have nothing in common. So, until this changes, I must resort to having plenty of air left over after my dives! ;-0
Thanks all for your replies and I will keep you posted on what DSAT/PADI says. I have finally received a response from Mr. Wohlers and it is only a matter of time now before I will know what will happen, if anything?
Toad :bonk:
Do I use the RDP?
NO! I have a fancy lil thingy called a Dive Computer and I no longer use the RDP personally. However, I am an Instructor and must teach new peeps the ins-and-outs of the RDP for them to successfully complete their Open Water Certification.
Table 1-2 shortcut?
Table 1 is where Table 3 comes from. The Wheel Version of the RDP matches Table 1 perfectly and shows the errors of Table 3. Look at the way you find your "Adjusted No-Decompression Limit" using the Wheel Version and you will find it is just the Table 1 - 2 method I have described for the Table Version. There is no Table 3 on the Wheel Version ... you have to figure it out doing that dreaded math thingy!
Babes?
I find that babe searching is always a good surface interval activity, as long as you don't ascend too fast to check-out the babes awaiting you at the surface. I guess patience is more than a virtue?
As to what the Pirate said in his posting:
My air consumption rate (ACR) allows me to exceed the NDL for any depth beyond 70 feet, so what you propose would not be wise in my case. I posted another question concerning ACR & the NDL, and it seems they have nothing in common. So, until this changes, I must resort to having plenty of air left over after my dives! ;-0
Thanks all for your replies and I will keep you posted on what DSAT/PADI says. I have finally received a response from Mr. Wohlers and it is only a matter of time now before I will know what will happen, if anything?
Toad :bonk:
BRW
Contributor
BF Toad,
"Peeps" you call them.
Are you referring to novice divers in your post?
Nice attitude.
And an interesting putdown from somebody who
believes "NDLs are related to air consumption rates", and
a "new thing" for computers. Plus one who pays slavish
attention to "table typos" with inconsequential impact on diving,
and misunderstands how tables are constructed.
And an air diver who "returns from beyond 70 fsw" with air
near NDLs and "uses a computer" pushes zilch on
the pool diving envelope. Extraordinary nothing.
Nobody in the diving instructional world has low
consumption rates. Will you teach us how?
And I sure hope you beat those pesky novices every time
on those "extreme" profiles to 70 fsw. Or less.
If not get an RB.
And did you fight oxtox, narcosis, and DCS too on
those plunges, along with air consumption? Bummer.
How did you survive?
Are you one of those shallow denizens who (only) dives air,
plunges to depths above 100 fsw, never stages, fears
deco at the NDLs, carries single tanks, never learned
and/or avoids buddy breathing, makes unnecessary safety
stops, practices emergency ascents in the horizontal
direction, and wears patches?
Are you a "peep recreational instructor"
Must be -- diving peepitis is rampant from whence you drift.
"Peeps" you call them.
Are you referring to novice divers in your post?
Nice attitude.
And an interesting putdown from somebody who
believes "NDLs are related to air consumption rates", and
a "new thing" for computers. Plus one who pays slavish
attention to "table typos" with inconsequential impact on diving,
and misunderstands how tables are constructed.
And an air diver who "returns from beyond 70 fsw" with air
near NDLs and "uses a computer" pushes zilch on
the pool diving envelope. Extraordinary nothing.
Nobody in the diving instructional world has low
consumption rates. Will you teach us how?
And I sure hope you beat those pesky novices every time
on those "extreme" profiles to 70 fsw. Or less.
If not get an RB.
And did you fight oxtox, narcosis, and DCS too on
those plunges, along with air consumption? Bummer.
How did you survive?
Are you one of those shallow denizens who (only) dives air,
plunges to depths above 100 fsw, never stages, fears
deco at the NDLs, carries single tanks, never learned
and/or avoids buddy breathing, makes unnecessary safety
stops, practices emergency ascents in the horizontal
direction, and wears patches?
Are you a "peep recreational instructor"
Must be -- diving peepitis is rampant from whence you drift.
BRW,
I fount that las post of yours really entertaining. This has to be some kind of record ol Toad posts on two threads and already gets chewed out by a real diving celebrity. Way to go Toad.
Every so often I am reminded ( because I sometimes get to dive with some very experienced divers on some dives that are a challange for me) of what I hope Toad was just reminded of and that is that I don't know so much. By the very nature of being an instructor I know more about diving than many of the divers I know. However, when one takes a look at where they are at compared to the best (not just the best in the room) it can be a sobering thought.
Best not to get overly cocky!
I fount that las post of yours really entertaining. This has to be some kind of record ol Toad posts on two threads and already gets chewed out by a real diving celebrity. Way to go Toad.
Every so often I am reminded ( because I sometimes get to dive with some very experienced divers on some dives that are a challange for me) of what I hope Toad was just reminded of and that is that I don't know so much. By the very nature of being an instructor I know more about diving than many of the divers I know. However, when one takes a look at where they are at compared to the best (not just the best in the room) it can be a sobering thought.
Best not to get overly cocky!
BRW
Contributor
Mike,
You are right on. None of us has all the
answers, and perspectives are important.
Didn't mean to be too hard on Toad, but
I don't cotton much to calling novices "peeps".
All were once on square one -- and Toad is
still there really.
Best regards to all,
You are right on. None of us has all the
answers, and perspectives are important.
Didn't mean to be too hard on Toad, but
I don't cotton much to calling novices "peeps".
All were once on square one -- and Toad is
still there really.
Best regards to all,
"peeps" is a term that kids use to mean "people." It doesn't mean novice or newbie. It is not a term used to put others down. I don't use it because it sounds silly. I think perhaps this is a case of, "None of us has all the answers, and perspectives are important."
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