Quiz - Recreational Dive Planner™ - Pressure Group After Third Dive

[Belzelbub]

Ran this with my SSI table and found that you cant run dive two. You'd have to back off to 40ft to run that bottom time at that SI. I'm surprised at how large of a difference that is.

Same here. Dive 2 was going to be a deco dive. At least on air. Which reminds me. I didn't see information regarding gas used. I made the assumption that since it was on a liveaboard, that the gas would be air, but that might not always be true.

 

[jonhall]

Learning from yesterday when I answered too quickly and it was then too late to change my answer after actually taking the time to read the question and what it was asking for......

My first time through on today's question, I missed, on table 3, that the first column was 35 feet and not 30 (a multiple of 10 like the rest of the depths) - I suppose when I glanced at the column I saw all of the depths that ended in 0 and pictured them all that way. I was glad the answer I first came up with was not one of the choices. When I went back and looked more closely I realized my mistake and then all was well with the world. If I used the RDP all of the time, that is not a mistake I would make - and now that I have used it for this question, I'll remember the first column in the tables is a multiple of 5 and not 10 like the rest of the depths...at least until I've had time to forget again.

Glad to be with the majority today!!!!

 

[Scraps]

I appreciate and look forward to Pedro’s daily quizzes.

I’ve often thought divers would be more likely to use the tables if they asked different types of questions about them, particularly the kind of question a diver might be curious about during a surface interval.

For example, if your first dive was 45 minutes at 58 feet and you know your second dive will be at 45 feet, how long must your surface interval be to stay down for the same length of time on your second dive?

I’ve never seen anyone outside of a class plan in advance a three-dive profile with the tables—because no one has specific enough information about the three variables.

However, the tables can be very practical supplements to the computer for conservatively planning your next step on a day of recreational diving. How long should this surface interval be to allow me to do the next dive? How long can this next dive be at my expected depth? Also, knowing the ballpark parameters gives a context for the information you expect to see on your computer.

 

[rhwestfall]

Those should be the next questions, but you need to be able to run the tables correctly first, hence the most recent exercise...

I have seen those questions at various certification levels.

 

[scubadada]

Thanks @Pedro Burrito

 

[scubadada]

Well... I fell down the rabbit hole of how the Padi RDP was developed.... some very informative reading...
octonion/scuba

Deco for Divers, Mark Powell, 2014, p 176:

The DSAT Recreational Dive Planner (PADI) model (1987)

The M-values used for the RDP were adopted from the Doppler bubble testing and tested by Dr Merrill Spencer and tested by Dr Raymond E Rogers, Dr Michael R Powell, and the colleagues with Diving Science and Technology Corp, a corporate affiliate of PADI. The DSAT M-values were empirically verified with extensive hyperbaric chamber and in water diver testing and Doppler monitoring.

 

[tursiops]

Ran this with my SSI table and found that you cant run dive two. You'd have to back off to 40ft to run that bottom time at that SI. I'm surprised at how large of a difference that is.

And that is EXACTLY why the RDP was developed. it was optimized 9and tested) for repetitive dives with shorter SIs.

 

[tursiops]

Fun!

Spoiler: wheel

The end letter was so close to interpret on the Wheel, I ran the tables too. Exactly how I would have answered it... and no, I didn't give up the answer

I haven't run the problem on the Wheel, but I'm surprised you get the same answer as the table. The Wheel allows 5 ft depth increments (one of its two advantages), so the second dive to 55 ft ought to (on the Wheel) pick up a little less gas....

 

[Pedro Burrito]

Spoiler: Answer

b. Metric N - Imperial O

 

[rhwestfall]

Spoiler: Wheel Answer

directly off the Wheel:
16 min @ 100' = K
1:10 SI = C
36 min @ 55' = S
2:30 SI = B
55 min @ 35' = O