Chapter 5- Decompression, Dive Tables, and Dive Computers Decompression, Dive Tables, and Dive Computers 135 4. Move across the row containing your corresponding block to the left until you come to another letter. For example, you had a Letter Group of G and you have been on the surface for 2 hours, so your new Letter Group is D. 5. Record the new Letter Group to the right of your SIT. Once you have determined your new Letter Group, you are ready to plan a repetitive dive. Planning Your Repetitive Dive When planning repetitive dives, you use the NAUI Dive Planning Worksheet as you did for the first dive (figure 5-15). However, you must use Table 3 to find your AMDT when planning your dive. Use the following steps to plan a repetitive dive: 1. Write your planned depth on the top line to the left of the second profile. For example, plan a dive to 15 meters (50 feet). 2. Write your planned depth plus three meters (10 feet) on the lower line to the left of the second profile. For example, your planned depth plus three meters (10 feet) is 18 meters (60 feet). 3. Look at Table 3 and find the AMDT for your planned depth. For example, the AMDT for 15 meters (50 feet) for Letter Group D is 51 minutes. 4. Record the AMDT next to your planned depth on the second profile. 5. Find the AMDT for your planned depth plus 3 meters (10 feet). For example, the AMDT for 18 meters (60 feet) is 31 minutes for Letter Group D. 6. Record the AMDT next to your planned depth plus 3 meters (10 feet) on the second profile. At this time, you have finished planning your repetitive dive regarding depth and time limits. Now it’s again time to dive your plan. Recording Your Repetitive Dive Recording your repetitive dive is similar to recording your first dive. However, this time you have residual nitrogen in your body and you must consider that before you find your new Letter Group (figure 5-16). Use the following steps to record your repetitive dive and find your new Letter Group: 1. In the time slot at the upper left corner of the second profile, record the time that you started your descent. For example, your second dive started at 12:35 p.m. 2. On the line to the right side of the second profile, record your deepest depth. For example, you went to 16 meters (52.5 feet). 3. In the time slot at the upper right corner of the first profile, record the time you completed your ascent. For example, you surfaced at 1:05 p.m. 4. Record your ADT at the bottom of the second profile (next to ADT). Remember to subtract your 3 minute precautionary decompression stop, which is considered neutral time. For example, your total dive time was 30 minutes – subtracting the 3-minute precautionary stop gives you an ADT of 27 minutes. 5. Find your RNT for your depth and Letter Group on Table 3. For example, you had a Letter Group of D and you went to 16 meters (52.5 feet), which gives you an RNT of 24 minutes. 6. Record the RNT at the bottom of the second profile (next to RNT). 00 : : : AMDT = 51 AMDT = 31 RNT = ADT = TNT = 15(50) 18(60) D FIGURE 5-15. THE DIVE PLAN FOR THE SECOND DIVE TO 15 METERS (50 FEET) HAS BEEN COMPLETED ON THIS WORKSHEET.
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