By now you're aware that you need to maintain neutral buoyancy while diving to avoid bottom tact, so you can relax and maneuver easily, and - you can prevent rapid, uncontrolled ascents and descents. In the last confined water dive, you adjusted your weight for neutral buoyancy at t1 surface. During this dive, you'll develop your n buoyancy skills further.

You've undoubtedly found that you need to use your BCD to trim and fine-tune buoyancy when you descend and ascend. due to exposure suit compression, and due to air compressing and expanding in your BCD. When making changes to your buoyancy, whether adding or releasing air, do it slowly. Rapid changes make it difficult for you to control buoyancy and can lead to runaway ascents or descents.

You've probably been using mainly your low pressure inflator to fill your BCDunderwater. To orally inflate your BCD underwater - which you might do if You had a low pressure inflator problem for instance, take your second stage in your right hand and the BCD inflator in your left. Take a breath, remove the regulator and blow about two thirds of this air into your BCD, operating the controls just like you did when orally inflating it at the surface. Save enough air to clear the regulator, and don't forget to blow a stream of bubbles as you switch back and forth - never hold your breath. Do this until you've inflated the BCD sufficiently to attain neutral buoyancy.

Let's look at the fin pivot method for establishing neutral buoyancy. This method guides you in getting the feel of neutral buoyancy. You'll practice doing this several times in the course, using both your low pressure inflator and your oral inflator. When you use your low pressure inflator, remember to add air in short bursts. Don't hold the button down continuously, and release air from your BCD in small amounts, too.
Basically, here's how you fin pivot: 

1) lie face down on the bottom, 

2) breathe slowly and deeply and 

3) add air in small amounts to your BCD (or dry suit - your instructor will give you more ,detail on this if you'll be using a dry suit), gradually increasing your buoyancy until you slowly pivot upward on.

Your fin tips as you inhale (buoyancy increasing with lung volume), and slowly pivot downward as you exhale (buoyancy decreasing with lung volume). This means you're neutrally buoyant at that depth and can fine tune your buoyancy by controlling your lung volume. Be sure you don't hold your breath at any time.

If you have a physical challenge that makes it difficult to pivot on your fin tips, you can use your knees or another contact point for pivoting. However, use your fin tips if you can because it puts all your body mass on.

After you've established neutral buoyancy, your instructor will have you swim 10 meters/yards or farther, remaining neutrally buoyant. During this swim, pretend you're swimming over a reef with sensitive aquatic organisms and avoid any contact with the bottom. This simulates how you swim avoiding damage to the environment when making open water dives.

Cramp Removal
A cramp is a painful, involuntary muscle contraction, which, as a diver, you may experience in your leg or foot muscles. Several things can contribute to cramps: dehydration, working the muscle beyond its fitness level, restricted circulation, cold water, and all of these working together. Your fins can contribute to cramping if the blade is too large for your leg strength, or if the foot pockets are too small and your feet don't go in them properly. Fitness, proper fin selection, practice, proper insulation and pacing your activity, will help you avoid cramps.

But they can happen anyway. Like most problems, it's more of an irritation than an emergency if you stop and think about what to do. For a cramp, stop and rest the cramped muscle. Stretch and gently massage it to increase circulation and pull out the cramp. If you have a leg cramp in your calf muscle, you can stretch it by grasping the fin tip and pulling it toward you while you push with your leg. Your buddy can also brace the fin tip for you

After relieving the cramp, rest the muscle for a few minutes before continuing at a slower pace - with about 50 to 75 percent of the load you had on the muscle before. A cramped muscle usually recovers better if you resume using it at a reduced pace after a brief rest than if' you stop using it completely.

TIRED DIVER TWO


Sometimes divers become so tired and out of breath they can't swim to the boat or shore. Or, they may have severe leg cramps that prohibit swimming, you can assist such a diver by establishing positive buoyancy and having the diver do the same, that helping the diver to the boat or shore using one of several tows, such as the tank value tow or the tired diver push, sometimes called the modified tired swimmer carry. Your instructor will demonstrate these and let you practice them

AIR DEPLETION/ALTERNATE AIR SOURCE COMBINED EXERCISE


During your first two confined water dives, you learned how to use an alternate air source, and you learned what it feels like to run out of air. Now you're going to put these together to practice responding to running out of air. Your instructor will turn off your air like when you did the air depletion exercise. 

Don't look at your SPG - but as soon as you feel breathing resistance, signal "out of air" and "share air" to your buddy. Secure and start breathing from your buddy's alternate; after you take a moment to get situated and make contact with each other, your instructor will have you swim together for at least one minute while you continue to use the alternate. This simulates swimming to the surface from 18 metres/60 feet deep.

As soon as you secure your buddy's alternate and remove your regulator from your mouth, your instructor will turn your air back on. That way, if you need to you can . Itch back to it. Confirm that the valve is open by checkin,,,Your SPG, which should not be on (or near) zero if it is.

 

Earlier you learned that it's not likely that vour regulator will fail so that it would cut off your air, but that a failure would most likely cause an air free flow. You can breathe from a free flowing regulator if you don't seal your lips on the mouthpiece. During this confined water dive, your instructor will have you
practice breathing this way

Since your regulator probably won't cooperate by spontaneously malfunctioning right when you need to practice this, you'll simulate the free flow by (you guessed it) holding in the purge button.

Remember to breathe withont sealing your mouth on the regulator, "sipping" the air you need while allowing excess air to escape. A free flowing regulator can really rush - don't be surprised if it jostles and floods your mask a bit. You'll breathe from your simulated free flow for at least 30 seconds, and your instructor may have you practice turning off your air after surfacing like you would with a real free flow. If you can't reach your tank valve unless you remove the scuba unit, do so for practice. Although your buddy might do this for you, doing it yourself develops self-reliance. Check your SPG when you're done; you'll be amazed how much air a free flow eats up in only 30 seconds - which is why you head straight for the surface if it happens.

Controlled Emergency Swimming Ascent


As you learned, the controlled emergency swimming ascent (also called CESA - pronounced "see-sa") is one option if you lose your air supply at 6 to 9 metres/20 to 30 feet or less, and your buddy is too far away to provide an alternate air source (Buddy system, buddy system! You shouldn't be that far from your buddy!).

Emergency swimming ascents are interesting because you start with air in your lungs, exhale all the way to the surface and still have air in your lungs when you get there. This happens because air expands in your lungs as you ascend; the potential hazard is a lung over expansion injury, which you avoid by not holding your breath.

To make a controlled emergency swimming ascent, simply swim upward with all your equipment in place, including your regulator. Look up, reach up and come up, swimming at 18 metres/60 feet per minute or slower. Exhale the entire time by making a continuous sound through your regulator as you ascend.

By saving, you exhale air at the right rate to prevent lung over expansion injury, but you don't exhale too much either The idea is to maintain a lung volume

Since you won't be 9 metres/30 feet deep during your confined water dive, you'll simulate the controlled emergency swimming ascent first horizontaly, then diagonally from deeper to shal lower water. You'll have enough air in your lungs to swim a long way horizontally while exhaling continuously, but 9 metres/30 feet will be ample for practice. After you do this horizontally, you can be more than sure that you can do it uerticallv assisted by air expanding in your BCD and lungs. After an actual controlled emergency swimming ascent, you don't feel out of breath-you still have air in your lungs. You'll get a chance to practice CESA vertically during your open water dives and may be surprised how much easier it is than simulating it horizontally.

Perhaps the greatest value of controlled emergency swimming ascent training is knowing you can do it. When you realize you can reach the surface without difficulty, even if you suddenly lose your air supply, you can relax and enjoy diving more. But watch your SPG and stay close to your buddy so you never need to.