when at rest. As you go deeper in the water, you will add small amounts of air to your BC to offset wetsuit compression or to your dry suit to achieve neutral buoyancy. You add just a small amount of air to your BC (or dry suit) and then check to see if you are still sinking by slowing your activity and breathing normally. If you are still sinking, add another small amount of air to your BC (or dry suit). As you ascend or you feel yourself rising in the water because of the expansion of air, you will need to vent small amounts of air from your BC, (or dry suit), to maintain neutral buoyancy. How much air you need to vent and how often you need to vent it depends on your situation and your depth. To vent air from your BC, (or dry suit), you must get into the necessary position first. Dump valves are usually located on the upper left shoulder of your BC and on the upper left arm of a dry suit. Some BCs have extra dump valves on either the lower back or top right side of the BC. If you have an extra dump valve, ask your instructor how to operate it. Slow your activity and your kicking from time to time to test your buoyancy. If you float up without kicking, you are too buoyant and need to vent some air. If you sink, you need to add a little air. You should strive to control your buoyancy so well that you can stop at any depth any time and remain suspended there without using your fins or hands. This technique is how you evaluate your buoyancy control and will be a part of your open-water training. Ascending For every descent you make, you must also make an ascent. Some of the general procedures for doing an ascent are: 1. Stop a minute and secure any accessories you are carrying. For example, if you are carrying a goody bag, close it and clip it to your BC. 2. Make sure your automatic exhaust valve will open if you are wearing a dry suit. 3. Find your power-inflator hose and your deflator/oral inflator valve button and hold the hose up over your head. If you are wearing a dry Chapter 3- Diving Skills suit, raise the exhaust valve until it is level with or above your shoulder (figure 3-48). Holding the hose over your head also ensures that your hand will run into an overhead object before your head will. 4. Give your buddy the up signal. 5. Start swimming slowly towards the surface with your buddy. Remember to look up and around as you are surfacing and breathe normally (figure 3-49). 6. Control your buoyancy and your ascent by venting air from your BC (or dry suit). Your rate of ascent must not exceed a speed of 9 meters (30 feet) per minute if you are using dive tables. This is only 15 centimeters (6 inches) per second and is much slower than you naturally want to proceed. If you are using a computer, following it will control your rate of ascent, and it might be slower than 9 meters (30 feet) per minute. 7. Slow your ascent when you get to 9 meters (30 feet). 8. Stop at a depth of 4 meters (15 feet) for 3 min- Diving Skills 75 FIGURE 3-48. IF YOU ARE WEARING A DRY SUIT, YOU MUST VENT AIR FROM THE SUIT AS YOU ASCEND.
20490TC
To see the actual publication please follow the link above