The whole concept of buoyancy control seems simple enough, you just add some air to your BCD, breathe right and you float though the water with the greatest of ease achieving what is called neutral buoyancy! Ah yes that effortless, fully in control completely relaxed state of diving.
Unfortunately buoyancy control for most divers is more like a constant tug of war with the power inflator hose. Too much weight sends you looking for the inflator hose with even the slightest change in depth. Too little weight and you struggle to stay down at depth, if you can reach depth that is. It is the intent of this article is to help improve your buoyancy through the suggestions of a few simple skills and techniques.
The first thing is to look at how we breathe. What does breathing have to do with buoyancy and equipment? Actually breathing is the key thing, we'll address the equipment issue but it is our breathing that fine-tunes our buoyancy. I suggest that you start by checking how you breathe. Ideally you should breathe by using your diaphragm, this way you will ensure a full exchange of oxygen within your lungs and you will be much more efficient and relaxed during the dive. Slow deep breathing and relaxation are key elements to good buoyancy control. In your basic open water class you may have been instructed that proper weighting was achieved by having no air in your BCD, holding your breath and the water should be approximately dissecting your mask at eye level. WAIT A MINUTE HERE! What did I see - holding your breath - I DON'T THINK SO! If you are not breathing and have the right amount of weight to off set the equipment and the environment to which you are diving in, then you are not properly weighted. Get your breathing settled down before you do anything else, slow deep diaphragm breathing.
Now let's look at the equipment you may be using and how you wear that equipment
First, look at some equipment characteristics. The scuba cylinder is often overlooked as an issue to consider for good buoyancy control. The fact is that depending on how big and what kind of material the cylinder is made of has a great effect on buoyancy. An aluminum cylinder when full will be negatively buoyant by as much as 8 pounds, but when empty that same cylinder at as little as 1000 psig will be more positive buoyant by as much as 1-2 pounds. A steel cylinder depending on cubic footage will be as much as 8-10 pounds negative when full. When empty that same steel cylinder will still be negative 4-6 pounds buoyant. That means that less weight can be carried when wearing a steel cylinder. It also means that when a cylinder is full that air does have weight and that you will be more negative at the start of the dive. We need to adjust our weights so that at the end of the dive when attempting to complete the safety stop we are correctly weighted and have achieved neutral buoyancy. Weighting is best checked with little to no air in the cylinder 700-500 psig.
The next thing to look at is the environmental protection suit you choose to wear based upon the environment you will be diving. Warm water requires a thinner suit whereas colder water requires a thicker suit. Salt water versus fresh water, you will require more weight in the salt water than in the fresh water by as much as 4-6 pounds of lead. Sometimes I have my students wear the environmental suit they will wear most often for the environment they will be diving. I have them wear a scuba cylinder with about 500-700 psig. They remove all the lead weight they are wearing and then we begin by placing the weight back onto them in small increments, usually in 2-3 pound packets or blocks. With no air in the BCD and a normal breathing rate achieved we adjust the weight until they can sink just by exhaling and remain below the surface breathing normally. At this point I have them practice the fin pivot to obtain neutral buoyancy. Further to this I have them practice changing their depth just by varying their breathing. From this the diver learns the key to buoyancy control, the BCD is used to make the course adjustments, and breathing is used to fine-tune buoyancy to perfection.
Ok so now we have the basic equipment used for adjusting our buoyancy
Our breathing is established, our BCD has the right amount of air in it, and the correct amount of weights needed to offset our diving suit in the environment to which we are diving, and we have a full cylinder, all things are good to go. So why is it that we still don't feel all that great stuff about neutral buoyancy. Well it may be the position we are floating at or we may still not be fully relaxed. First of all lets just relax. We can practice this by not moving, no kicking, no sculling - nothing just freeze and see where you end up. Too much movement when attempting to obtain neutral buoyancy can make the difference between good and great buoyancy control.
Secondly we may need to trim ourselves properly. This means to ensure that we have positioned our weights and scuba cylinder to the correct ballast point to where we feel most comfortable. Make sure that you have even weight distribution from head to toe and left to right. Make a note of the material your fins are made of. Some fins sink while others float, Some BCD's have the use of rear weight pockets to distribute weight across the body. You can also strap weights to your BCD's tank band and trim yourself quite effectively with no lessening towards your safety should you need to ditch your weight in an emergency. Some divers use ankle weights as a means to distribute weight. You can even place an ankle weight up around the tank valve to assist you in trimming. And lets not forget that where we position our scuba cylinder itself will have a great affect on our buoyancy and trimming. A scuba cylinder, worn high places us in a more head down position, a cylinder worn too low places us in a feet heavy position. Try moving your cylinder up, taking care not to bump your head when you look forward. The advantage of this is you will find you are actually more streamlined and your breathing and movements will become easier and better. As an added result of regulator mechanics you'll have improved air consumption because your regulator will be working at a greater pressure than your lungs, if only by a few inches.
Once you get all the tricks mastered you'll be able to breath your way up and down the water column, around the reefs or through a hole in a shipwreck (avoid overhead environments unless you are properly trained to dive in these areas). The type of BCD you choose be it back inflation or jacket style will also affect your in water position but with practice you'll soon master control of that as well. Practice your buoyancy skills on each and every dive even if only for a few minutes, it will most certainly make a difference in the enjoyment of your diving.
Keep Diving .. Keep Training!
If you have questions, or if there is a topic you'd like to see covered in a future training article, please contact us.