View Full Version : PADI Dive Table Question

02-29-2008, 08:49
Hi All,
I'm in the process of my OW training and came across a question I don't understand the answer to. I was hoping someone here could shed some light on what I did wrong:

Imagine you have done a dive and you have stayed on the surface for a while. After this surface interval your pressure group on the Recreational Dive Planner is F. What is the maximum amount of bottom time you can spend doing a repetitive (second) dive to 17 metres/56 feet?Correct Answer(s):D. 36 minutes
Your Answer(s):A. 19 minutes

I answered 19 minutes, the correct answer was 36 minutes. why?


No Misses
02-29-2008, 09:36
It has been a while but here goes...
Looking at the back of the PADI Air table
Round 56' up to 60'
follow that over until you get to the "F" column
You will see two numbers. The white box is 19 and the blue box is 36
The white box is your RNT (Residual Nitrogen Time). You add RNT to your ABT (Actual Bottom Time) to figure out your new Pressure Group.
The Blue Box is the maximum amount of time or ABT (Actual Bottom Time) that you can dive at this depth. Notice that if you add this number to your RNT (White box) and look at table #1 your planned dive would be at the NDL (No Decompression Limit).

In your case if you added 19 minutes (RNT) to 36 minutes (ABT) you get 55 minutes at 60 feet. look at table #1. This is the NDL for your second dive. You would be at Pressure Group "W".

That was the long answer.

THE SHORT ANSWER IS...The number in the blue box is the max bottom time for your next dive at that depth.

I hope this helped.

02-29-2008, 09:41
Please download the software available on the ScubaToys website. It's a wonderful tutor and testing program for using and learning the Recreational Dive Planner.

Best of all. It's FREE!

It really helped me go from barely understanding how to use the tables, to mastery.

No Misses
02-29-2008, 09:45
BTW: I had to go find a copy of the tables online before I could answer your question. I needed the refresher :-)
Here is the link to the planner that I found

02-29-2008, 10:03
This is the very reason my wife will not dive..."just to much calculations"...I tell her it is simple math and a chart--lol!!!

02-29-2008, 12:08
Thank for all the answers. NoMisses. you explaination makes sense. Thanks for the link also.


02-29-2008, 12:16
Yep, been certified for a while now...still hate tables...thought I was done with them....then took Nitrox...darn it....

02-29-2008, 12:22
The tables seem fairly straigh forward, just need learn when to use which table. The Table Tutor (as recommended above) was a great help thus far.

I'm looking forward to get ceritified, my wife is SSI and I've done Discover Scuba in the Caymans. Going to HI next summer.

03-02-2008, 08:33
I thought tables would go out the door after AOW, now that I'm moving towards technical diving here they come again but now with more gusto. I don't think they're ever going to go away, like a bad penny they keep coming back.

The planner also on scubatoys sight here, plus if you email Larry or Joe you can get the registration number for it as well.