1. Use the Proper Weight
Using the proper amount of weight is key to buoyancy control. Most new scuba divers begin a dive overweighted, resulting in more use of the buoyancy compensator low pressure inflater as changes in depth occur. So what is the proper weight? The most common answer is when you are on the surface, you should be at eye level with the water with no air in your BCD. However, this is with a full tank. As you use up your air, your scuba tank will become positively buoyant. This is especially important at your 15 foot safety stop because if you use the above method, you will be underweighted and will begin floating toward the surface. Consequently, you should be a little negatively buoyant (1-2 extra pounds) at the surface with a full tank and no air in your BC and your lungs half-full. Your goal is to be neutrally buoyant at your 15 foot safety stop. So at your safety stop with no air in your BCD, if you are motionless (concentrate on that!) and you start ascending, you’re underweighted. Conversely, if you are sinking, you are overweighted. Make adjustments in 1-2 lb. increments on your next dive.
This method is also cited in articles on DAN’s website (Divers Alert Network, a non-profit organization that provides emergency medical advice and assistance for underwater diving injuries).
2. Be Patient and Inflate/Deflate in Small Increments
When you add or release air from your BCD, give it time to take effect – It will not be instantaneous. If you don’t give it a bit of time, you will have the tendency to over-inflate (or deflate). A few seconds wait should be sufficient. Also, just give the BCD a small burst (or release) of air. See if that is sufficient. If not, you can always add more air. Your goal is to reach that neutral feeling and not over-inflate or under-inflate.
3. Remember the Effects of Your Wetsuit
Remember that you will become less buoyant as you descend in the water column. As your wetsuit becomes wet and the bubbles in the wetsuit compress from the pressure, the suit will lose a small amount of buoyancy. You may think you are underweighted at this point but wait until you a down for a bit before you decide – especially if you are unfamiliar with the affects of your wetsuit. In addition, your wetsuit will lose some of its buoyancy over time as the bubbles break down. Unfortunately, it also means that it will lose some of its insulation properties and become ineffective.
4. Empty Your BCD
If you feel you are underweighted, make sure your BC is empty of all air. Sometimes air bubbles can get trapped inside; the effect of which will be magnified as you ascend. Some tips to get the last of the air out of your BCD: Hold the inflator hose straight up while pressing the deflate button; Hold the right side of your BCD against your body and tilt a little to the right; Go upside down or inverted and pull the dump valve(s) on the lower back of your BCD; and, Roll backwards a little and give a little shake.
5. Stay Horizontal
You should be horizontal in the water so your kicks propel you forward and not upward. Concentrate on pointing your toes, extending your leg at the knees and kicking from the hips. Most new divers bicycle kick or crawl in the water, resulting in a slight incline in posture. You may have to adjust where your weights are to accomplish this. It is also a function of experience, so be patient.
6. Breath Control
Don’t forget about the air in your lungs. Do not hold your breath – besides being dangerous, it will give you extra buoyancy. Eventually you will get to the point where you can ascend or descend a few feet solely by breathing in or out.
7. Dive, Dive, Dive
Like all scuba diving skills, the more you practice them, the easier it will be. Learn to relax underwater and determine your ideal weight for the conditions (e.g., fresh or salt water) and equipment (e.g., dive skin or 5mm wetsuit) early in your diving career. Soon you will be diving without even giving scuba diving buoyancy a second thought.