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NAUI Master Scuba Diver 242 Diving Techniques and Deeper Diving POTENTIAL HAZARDS When, for various reasons, things do not go according to plan during a deep dive, you need to be prepared to deal with any problems that occur. Some potential problems are listed below, along with suggestions for dealing with them. • Emergency Decompression: If the no-decompression limits are unintentionally exceeded, you must make whatever decompression stop(s) is/are required. • Omitted Decompression: The U.S. Navy procedure for omitted decompression, which involves recompressing the diver in the water, is no longer a viable option. In-water decompression has been eliminated as an acceptable procedure based upon recommendations by noted physicians and physiologists. If required decompression is missed, you should remain out of the water, rest, breathe 100% oxygen, drink fluids, and be alert for signs and symptoms of decompression sickness. If bends are suspected, proceed at once to the nearest medical facility for medical examination and possible transport to a hyperbaric facility. The Diver’s Alert Network (DAN) should be contacted at (919) 684-9111 by the attending physician. In-water decompression does not eliminate bubbles once they have formed and can make the situation much worse than it would otherwise be. A bent diver requires medical attention and recompression in a controlled, air environment. • Rapid Ascent Rate: If for some reason your rate of ascent is too fast and you are able to arrest it at a depth greater than 6.1 m (20 ft), simply pause for the estimated length of time it should have taken you to reach that depth if ascending at the proper rate. If an uncontrolled ascent takes you all the way to the surface from a depth greater than 9.1 m (30 ft), you should get out of the water, breathe pure oxygen, and watch for signs of decompression sickness. • Cold or Strenuous Dives: If a dive is particularly cold or strenuous, use the next longer bottom time schedule. If a dive is cold and strenuous, the same adjustment should be made. • Instrumentation Failure: If your instrumentation providing information about your decompression status fails, you should ascend to a depth shallower than 9.1 m (30 ft) and then perform precautionary decompression appropriate for your best estimate of your decompression status. Your buddy’s instruments may help you to estimate your decompression status. If, to the best of your recollection, you are well within the no-decompression limits, a simple precautionary stop may suffice. If, on the other hand, you are uncertain about your decompression requirements, extended decompression is recommended. After surfacing, diving activities should be terminated for 24 hours. • Separation from Buddy: Deep diving requires close visual contact between buddies. If you become separated, you should strive to regain contact with your buddy as soon as possible. Look for exhaust bubbles for about one minute, then begin to ascend while scanning the water around you. You will have to perform your safety stop due to the deep dive. If your buddy does not meet you on the surface, you will have to make the decision as to whether or not to descend again to search. You should not jeopardize your personal safety if you do not have sufficient time remaining to dive again to the depth in the area you were separated. Diver rescue from great depths may also be particularly challenging. Effects of Increased Pressure The obvious effects of increased pressure are that increased exposure to higher ppN2 can cause decompression sickness and/or narcosis (covered in detail in “Physiology” chapter). The risk of decompression sickness will be minimized greatly by staying above 24.2 m (80 ft) and planning your dives conservatively to remain well within the no-decompression limits. Bounce dives, which are successive, relatively short up and down dives, are to be discouraged, as they apparently favor bubble formation. Most decompression experts suggest at least a one hour surface interval between dives. Other effects of increased pressure include increased breathing resistance, anxiety, and the potential for ear equalization problems. More subtle, but nonetheless important minimizing factors include common sense things like getting a good night’s sleep, eating a good breakfast, and drinking plenty of fluids (non-alcoholic).


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