Chapter 5- Decompression, Dive Tables, and Dive Computers Decompression, Dive Tables, and Dive Computers 129 progressively shallower dives and prevents you from carrying progressively larger amount of residual nitrogen on deeper repetitive dives. • Consider any dive shallower than 12 meters (40 feet) to be a 12-meter (40-foot) dive when planning your dives. • Surface Interval Time (SIT) must be at least 10 minutes between dives. If your SIT is less than 10 minutes, you must consider your second dive as a continuation of the first dive. NAUI recommends a SIT of at least one hour between dives. • Use the next greater dive time if your dive is particularly cold or strenuous. For example, if you do a dive to 18 meters (60 feet) for 22 minutes, the 22 minutes rounds to 25 minutes. However, if you become chilled during the dive, round the time again to 30 minutes. • Avoid dives that take you right to the no-decompression limit for any given depth and time combination. If you accidentally overstay your bottom time or use an incorrect ascent rate on such a dive, you could be in a required decompression situation or suffer DCS. Always allow yourself enough time to make a slow, comfortable ascent with plenty of air. Verify What You Have Learned Review the following questions about Dive Table Rules: 5. When you use the NAUI Dive Tables, you ascend from all dives at a maximum rate of ______ meters (______ feet) per minute. 6. You should allow a minimum of _____ minutes between dives and NAUI recommends a SIT of ______________. 7. Arrange the following dives into the preferred sequence: ___ 9 meters (30 feet)/40 minutes ___ 18 meters (60 feet)/30 minutes ___ 15 meters (50 feet)/20 minutes 8. A dive of up to 8 meters (26 feet) for 40 minutes should be considered as a dive schedule of ________________ when planning a repetitive dive. DIVE TABLE ORGANIZATION The NAUI Dive Tables are composed of three tables: • Table 1 – End-Of-Dive Letter Group • Table 2 – Surface Interval Time (SIT) Table • Table 3 – Repetitive Dive Timetable The NAUI Dive Tables are based on the US Navy Decompression Tables and have been designed specifically for recreational diving (figure 5-6). The tables are designed to flow from one to the other in a continuous loop (figure 5-7). When you are using the tables, be sure to use a ruler or a straight-edged object to read the numbers across and work your way from table to table. If you try using a finger to trace your path through the tables, you might slide into another row and read the table incorrectly, especially if you are on a rocking boat. FIGURE 5-6. THE NAUI DIVE TABLES HAVE BEEN DESIGNED FOR RECREATIONAL DIVING AND ARE EASY TO USE.
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