You may have read the post on Calculating your No Decompression Limit, NDL
\nand are here to learn more of what the RDP can do. Better stated, what you can
\ndo with your RDP!
\nNote, even though electronic versions of the RDP are available, they are too
\nsimplified when compared to walking through the tables. The results of the two
\nwhen compared should be very similar. Besides, they are electronic and didn’t
\nI mention something about electronics going out and reverting back to the
\ntables in my previous post? Ah huh.. So let’s move on.
\nRDP Plus take the basics of calculating your No Decompressiong Limits and
\nshows others ways to use your RDP. For example, to calculate the amount of
\nsurface time needed to support another dive to a specific depth for a specific
\namount of time.<\/p>\n
Let’s take a look at the RDP. What I am about to describe holds true for all
\nof the DSAT RDP’s and most other organizations rendition of the RDP.
\nThe RDP contains three tables. On the front you may find two tables. Table 1,
\nthe No Decompression Limits and Group Designation Table and table 2, the
\nSurface Interval Credit Table. On the reverse may be found table 3, the
\nRepetative Dive Timetable. Three tables.<\/p>\n
It takes knowing only two of the three table values to figure out the third
\ntable’s value. For example, if you know the depth and time at depth (table 1),
\nand the depth for the subsequent dive (table 3), you are able to calculate the
\nsurface interval (table 2) \u00a0needed to support the time at depth for the
\nsubsequent dive.<\/p>\n
Let me word it a different way. Let’s say you want to dive to 80 feet for\u00a025 minutes. So how do you use the RDP to calculate Surface Interval Time? The legend on the bottom right states the bottom number is our No Decompression What you just just learned is to move from pressure group N to pressure group C
\nThen your second dive, you would like to dive to 60 feet for 40 minutes, how much
\ntime must you spend on the surface that will allow you the 40 minutes at 60 feet?
\nThe answer: between 1:09\u00a0 and 1:30 hrs\/mins.<\/span><\/p>\n
\nLet’s use the example just used above and we’ll walk through the flow on the RDP.
\nFollowing a dive to 80 feet for 25 minutes your pressure group is\u00a0 N<\/strong>. You desire
\nto dive to 60 feet for 40 minutes for your next dive. Using table 3, locate 60 feet.
\nFollow the row until the 60 feeet and your current pressure group, N intersect.
\nYou should find the box with the numbers 35 over 20, 35\/20.<\/p>\n
\nLimit. In this case, 20 minutes. This is telling you that if you were to enter the water
\nwith a Pressure Group of N and decend to 60 feet, you would have 20 minutes of
\nno decompression diving available. Yet, you desire to spend 40 minutes at 60 feet.
\nHow do you get enough credit to perform a dive to 60 feet, simple, spend more time
\non the surface. How much time? You know you want 40 minutes, so still on table 3,
\nlook at the line for 60 feet and follow it to right right until you find a number in the
\nblue box that is 40 or greater. Scanning we find the column at pressure group C,
\nwhere Pressure Group C and the 60 foot row intersect the pair of nunbers 14\/41.<\/p>\n
\nyou must spend some amount of time on the surface. Flip the card over to view
\ntable 2. Finding the Pressure Group C located at the bottom of the card, work
\nyour way up until the Pressure Group C column meet the Pressure Group N.
\nThe pair of numbers in the box informed you of the amount of surface time
\nrequired to move from the N pressure group to the C pressure group. In this case
\n1:09\/1:30. That’s 1 hour 9 minutes to 1 hour 30 minutes.<\/p>\n