Chapter 10- Diving Techniques and Deeper Diving Diving Techniques and Deeper Diving 245 computers compute air consumption and display the number of minutes of air time remaining at current air consumption rate. This is a valuable asset, especially for a novice deep diver. Some divers will move to the furthest planned distance from the ascent line immediately upon reaching the bottom and slowly work their way back to the line. Ascent Ascend as a buddy team, facing each other with one hand on the ascent line. Discharge air from the BCD (and/or dry suit) as needed and remain neutrally buoyant throughout ascent. Some divers use slight positive buoyancy and do not even kick as they ascend the line. Maintain an ascent rate that does not exceed 9 m/min (30 feet/min), or slower if your computer or dive tables dictate. Use your dive time/depth gauge or dive computer to monitor ascent rate. Remember, at an ascent rate of 9 m/min (30 feet/min), it takes 20 seconds to ascend 3 m (10 ft). Keep in mind that a proper ascent is a controlled ascent. And, ascent control is directly dependent on a diver’s buoyancy control skill. Safety or Decompression Stop Non-technical recreational divers are to avoid exceeding the no-decompression limits for the maximum depth of any dive. During ascent from any dive, divers are encouraged to make a safety stop at 5 m (15 ft) for 3 to 5 minutes. This is essential when ascending from a no-decompression deep dive (figure 10-5). It is recommended that divers make a two to three minute stop at a depth that is half that of the deepest depth reached during the dive and make a precautionary stop in the 3-6 m (10-20 feet) zone for one minute before returning to the surface. Exit and Post-Dive Activity Upon completion of the safety stop, divers should ascend slowly to the surface. Remember that it should take at least 30 seconds to ascend from the stop (a depth only 1 m 3 ft deeper than the average pool). Persons returning from a deep dive should not be required to manually retrieve the anchor or descent-ascent line bottom weight. Do not ascend to altitude for 12 hours (24 hours following a mandatory or emergency decompression dive). In the majority of cases of decompression sickness, symptoms manifest in less than two hours following the dive. Divers should remain with other divers for at least a two-hour period. Divers should monitor themselves for 24 hours for any unusual symptoms that might suggest decompression sickness. Finally, enter the dive information in your log book. SUMMARY Deep diving is an activity that requires training, experience, and knowledge of the increased potential hazards involved with diving to deeper depths. Advanced information and training in the areas of decompression, dive planning, equipment requirements, and emergency procedures is required. Deep diving can be exciting and rewarding, but should only be considered after the proper training and certification has been successfully completed. FIGURE 10-5. DECOMPRESSION STATION WITH EXTRA CYLINDER AND REGULATOR
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