RDP Chart

Question
QUESTION: Thank-you for your time in answering my question.
I am a bit confused when calculating the following types of questions: Example

If you planned to dive to 82 feet and want to make two 20 minute dives . What is the minimum surface interval that I must have between these two dives.  Remembering that minimum surface intervals are for training purposes ONLY.   When diving, I always want to be conservative.

When you look on the RDP chart, is the answer always group A? So the answer to this question is goto depth 90 feet and down to 21 minutes which is (PG) M then across to A and minimal surface interval is 2:15?

I hope I didnt make this sound to confusing.

Thank-you.


ANSWER: Hi,

Are you a certified diver?  If so, are you using the RDP to plan dives?  If so, what level is your certification.

saludos,
James

---------- FOLLOW-UP ----------

QUESTION: Hello James,

Thank-you for the promt reply.

I am currently taking the open water certification and I am practicing RDP questions.  This is one question I came across and I have not met with my instructor to ask the question, so I was looking to find the answer on my own.

also if you have a list of sample questions I can practice with or know a website that has posted questions with answers, that would be very usefull.

Answer
OK, got you.

I don't have an RDP in front of me, but basically you start out at the base level A and use the table to find your exit group (given max depth and time), then you find your group after your surface interval, which then shows you your available time for given depths for your follow-up dive.

It's probably a good idea to read something like this:
http://www.scubadiverinfo.com/2_divetables.html
and the image on that page links to a larger version you can print out if you need it.

NAUI and PADI use the same table types, as far as I know.

Hope that helps!

saludos,
James