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  RDX - Recreational Diving Experience Index
Sea Turtle 
RDX is a personal dive history condensed into one number to give an overview of a diver's experience. RDX represents not only a number of dives or a total bottom time, but also takes into consideration experienced diving conditions and diversity of the diving. In adition, RDX accounts for downgrading of experience with time.

  RDX can be used to compare recreational diving experience of two divers, or to rank a diver's experience in comparison with others. The table on the rightshows percentile ranks of RDX. For example, RDX48.4has a65th percentile rank, which means that65% of divers have RDX lower than 48.4.

The following are the principles for calculating RDX:

 • A contribution of a dive to RDX is a sum of contributions from the following five categories: bottom time, maximum depth, lowest temperature, visibility, and location familiarity.

 • Each category in its "easiest" case - short bottom time, shallow, warm, clear water, familiar location - contributes 0.1. The contribution of a "really easy" dive, with all categories on their easiest level, is equal to 0.5 (five times 0.1).

 • Each category in a "difficult" scenario - very long dive, deep, cold, bad visibility, non familiar location - contributes a full 1. So, a "difficult" dive counts as 5.

 • Novelty of a location loses 25% with every dive.

 • A contribution of dive to RDX depends upon how long ago the dive occurred - it loses 25% every year. So, if today a dive's contribution into RDX is 4, then in one year from today it will be 3, in two years - 2.25, etc.
Rank RDX
99 565.7 
95 210.0 
90 136.1 
85 98.1 
80 74.5 
75 60.5 
70 51.8 
65 44.8 
60 35.5 
55 30.2 
50 25.5 
45 21.9 
40 19.4 
35 15.6 
30 13.3 
25 11.6 
20 9.3 
15 8.1 
10 6.9 
5 4.9 
1 0.5 
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