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Chapter 5- Decompression, Dive Tables, and Dive Computers Decompression, Dive Tables, and Dive Computers 141 For example, you can dive to 24 meters (80 feet) for a MDT of 35 minutes. If your ADT was 38 minutes, your excess time is 3 minutes. The first time that equals or exceeds your excess time in column two is 5 minutes. 3. Decompress at 5 meters (15 feet) for the time indicated in column three. As you can see, using the NAUI Dive Time Calculator is even easier than using the NAUI Dive Tables. SAMPLE PROBLEMS Use the NAUI Dive Tables or the NAUI Dive Time Calculator to solve the following dive profiles: 1. Your first dive of the day is planned for a depth of 18 meters (60 feet), begins at 9:30 a.m., and lasts for 23 minutes. The actual depth of the dive is 16.7 meters (55 feet). You make a precautionary decompression stop at 5 meters (15 feet) for 3 minutes, you surface at 9:56 a.m. and remain out of the water until 10:40 a.m. Your next dive is to a depth of 15 meters (50 feet) for 23 minutes. You make a precautionary decompression stop at 5 meters (15 feet) for 3 minutes. You surface at 11:06 a.m. and have a SIT of 1 hour and 50 minutes. At 12:56 p.m., you begin your third dive to a planned depth of 12 meters (40 feet), but you end up reaching a depth of 13.7 meters (45 feet) with an ADT of 30 minutes. You make a precautionary decompression stop at 5 meters (15 feet) for 3 minutes and you surface from the third dive at 1:29 p.m. What is your final Letter Group? 2. Your first dive of the day begins at 8:00 a.m. and is to a depth of 18 meters (60 feet) for 31 minutes. You make a precautionary decompression stop at 5 meters (15 feet) for 3 minutes. You surface at 8:34 a.m. Your SIT is 1 hour and 31 minutes. The second dive begins at 10:05 a.m., is to a depth of 16.8 meters (55 feet), and lasts for 24 minutes. You make a precautionary decompression stop at 5 meters (15 feet) for 3 minutes and surface at 10:32 a.m. Your third dive, which begins at 12:36 p.m., is to 15 meters (50 feet) for 31 minutes. What time do you surface from this dive and what is your Letter Group? 3. Your first dive is to 18 meters (60 feet) for 30 minutes followed by a 30-minute SIT. The second dive is to 15 meters (50 feet) for 30 minutes. What is your Letter Group after the second dive? 4. Your first dive is to 17 meters (56 feet) for 31 minutes and it is followed by a 1 hour SIT. The second dive is to 16 meters (52.5 feet). What is the AMDT for the second dive? What is your Letter Group if you reach the AMDT? 5. After the second dive in problem 4, how long a SIT is required to make a 25-minute dive to 15 meters (50 feet) without exceeding the AMDT? What is your Letter Group following the third dive if your ADT is 25 minutes? USING THE REDUCED GRADIENT BUBBLE MODEL (RGBM) TABLES There are many different models used in calculating nitrogen on and off gassing for dive tables and computers. As part of your NAUI Master Diver course, you will learn more about the various models used for these calculations. FIGURE 5-19. THE COMPLETE SET OF RGBM TABLES WHICH INCLUDE TABLES FOR AIR, EAN32, & EAN36, EACH AT 3 DIFFERENT ELEVATION RANGES.


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