NAUI DIVE TABLES

Table 1

End-Of-Dive Letter Group gives you a Letter Group designation at the end of your dive (figure 5-8). This table also gives you the Maximum Dive Time (MDT) information for depths from 12 meters to 39 meters (40 feet to 130 feet). The MDTs are the red, circled numbers.
  1. The table is arranged with the depths in columns on the left side of the table and the times for each depth in rows across the table. To find your Letter Group, use the following steps:

  2. Take the deepest depth you reached during your dive and round it to the next greater depth found in Table 1. For example, if the deepest part of your dive was to 22.5 meters (75 feet), round the number to 24 meters (80 feet).

  3. Locate the row corresponding to your deepest depth.

  4. Follow the row across until you find the column containing the total time of your dive. You might have to round the total time of your dive to the next greater time found on the table. For example, if the total time for your dive to 22.5 meters (75 feet) was 26 minutes, you must round the time to 30 minutes.

  5. Follow the column containing the total time of your dive down until you reach a letter. This is your Letter Group designation for your dive. For example, the Letter Group for the dive to 22.5 meters (75 feet) for 26 minutes, which is rounded to 24 meters (80 feet) for 30 minutes, is G.
The longer you stay on the surface between dives, the more excess nitrogen you eliminate. Table 2 - Surface Interval Time (SIT) Table gives you credit for eliminating nitrogen by changing your Letter Group. Table 2 consists of blocks containing two numbers. The numbers are expressed as hours and minutes. The lower number in the block is the minimum Surface Interval Time (SIT) for a particolar group and the upper number is maximum SIT for a particolar group.

Table 2

To find your new Letter Group based on your SIT, use the following steps:
  1. Look across the top row of the table until you come to the Letter Group designation you had at the end of your previous dive. For example, you had a Letter Group of G.

  2. Go down the column until you find the block into which your SIT fits. For example, you were out of the water for 3 hours. The block into which 3 hours fits is the one which starts at 2:59 and ends at 4:25.

  3. Move left across the row containing your corresponding block until you come to another letter. For example, if you had a Letter Group of G and were out of the water for 3 hours, you woold have a new Letter Group of C.
Note that the maximum time in this table is 24 hours. All excess nitrogen is considered eliminated after you have been on the surface for 24 hours. Therefore, a dive after 24 hours on the surface is not considered a repetitive dive.

Table 3

Repetitive Dive Timetable provides your Adjusted Maximum Dive Time (AMDT) for your next dive and your Residual Nitrogen Time (RNT) based on your current Letter Group. You use this table twice for each repetitive dive. First, you use the table to find your AMDT when planning your dive. Next, you use the table to find your RNT after you complete your dive. You add the RNT to your Actual Dive Time (ADT) to find your Total Nitrogen Time (TNT).

The table is arranged with the depths from 12 meters to 39 meters (40 feet to 130 feet) in columns across the table and the Letter Groups in rows down the table. Each block of the table contains two numbers. The upper number is the RNT corresponding to each depth and Letter Group. The lower, red number is the AMDT for each depth and Letter Group.

Use the following steps to find your AMDT when planning a repetitive dive:

  1. Find your new Letter Group, based on your SIT, in the column on the right side of the table. For example, you have a new Letter Group of C.

  2. Search along the row corresponding to your Letter Group until you come to the column corresponding to the depth to which you want to dive. For example, you want to dive to 15 meters (50 feet).

  3. Look at the lower number to find your AMDT. For example, with a Letter Group of C, you can dive to 15 meters (50 feet) for a maximum of 59 minutes.
Use the following steps to find your TNT at the end of your repetitive dive:

  1. Find your new Letter Group, based on your SIT, in the column on the right side of the table. For example, you have a new Letter Group of C.

  2. Move along the row corresponding to your Letter Group until you come to the column corresponding to your deepest depth during the dive. For example, you went to 14 meters (47 feet), which rounds to 15 meters (50 feet).

  3. Read the upper number in the block. This is your RNT. For example, the RNT for a dive to 15 meters (50 feet) for Letter Group C is 21 minutes.

  4. Add the RNT to your ADT to find your TNT. For example, if your ADT was 35 minutes, you must add your RNT of 21 minutes from step 3 to get a TNT of 56 minutes. Note that the AMDTs and RNTs in each block add up to the circled MDT for each corresponding depth in Table 1.

Dive Table Problems