Chapter 4- Diving Science Diving Science 105 You can function almost normally while under the pressure of water. To be comfortable, you must keep the pressure in the air spaces inside your body equal to the pressure surrounding your body. One of the important lessons you will learn in your NAUI Scuba Diver certification course is how to equalize pressure under water. Verify What You Have Learned Complete the following chart for a given quantity of air in a balloon: Pressure Volume Density Doubles Halves Doubles One third Halves Quadruples How Pressure Affects Air Consumption The deeper you dive, the greater the surrounding pressure. The greater the surrounding pressure, the denser the air that you breathe and the faster you empty your cylinder. The rate at which you consume the air in your cylinder is directly proportional to the depth of your dive. You consume your air twice as fast at 10 meters (33 feet) as you do on the surface, three times as fast at 20 meters (66 feet), and so on. This is readily seen by considering these depths as multiples of atmospheres of pressure. Air Consumption Factors Other factors also affect the rate at which you consume air on your dive. These factors include: • Your activity level during the dive. • Your mental state. • Your body size. • The warmth of your diving suit. • Your level of physical fitness. Besides depth, physical activity has the greatest effect on your air consumption under water. You can use up to 4 times more air when you are exerting yourself than when you are resting. Improving your air consumption is not the only reason to avoid exertion under water, but it is certainly one that good divers keep in mind. Beginning divers tend to be more active than necessary, but they quickly learn how to relax under water. During the first few dives after training, a new diver’s air consumption rate decreases significantly because they learn how to relax. With experience, these divers also learn how to move through the water more efficiently. The sooner you can do this, the more enjoyable your diving will be. As a diver, you need to think about developing a slow and relaxed breathing pattern as well as a slow rate of breathing. When you swim fast under water, you breathe more deeply and more often. Therefore, you use more air. You can waste a lot of air if you breathe shallowly and rapidly. If you limit your exertion and relax during your dive, you will be able to maintain a slow, deep pattern of breathing with Density x 1 0'–1 ata Density x 2 33'–2 ata Density x 3 66'–3 ata Density x 4 99'–4 ata FIGURE 4-19. THE DENSITY OF AIR INCREASES AS THE PRESSURE INCREASES.
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