Neutral Buoyancy, a rule to dive by!
Why is neutral buoyancy so important? Neutral buoyancy is not only an important skill for your diving comfort, it is also very important for your safety and the environment. There are many nasty creatures that live on the sea floor, the Spiny Sea Urchin and the Stonefish, not to mention the many homes that exist in the sand and between corals. Imagine a giant crashing down onto your home; this is exactly what the Bulldozer Shrimp and Goby feel like when divers land knees in the sand while they attempt to adjust their buoyancy.
What is neutral buoyancy? A ship is positively buoyant because it floats; the anchor is negatively buoyant because it sinks. We as scuba divers want to be neutrally buoyant underwater as to not sink or float. We want to be like astronauts in space, weightless!
How do I know if I have enough weights? Well, we will perform a weight check before the dive. With a completely empty BCD and lungs full of air, you should float at eye level at the water surface. Remember to keep into account that a full aluminium cylinder becomes more buoyant when it is empty and a full steel cylinder becomes less buoyant when empty. This means you should perform a weight check with an empty aluminium cylinder and a full steel cylinder.
Factors to consider
What affects my buoyancy? There are quite a few factors. This is a short list on factors which affect buoyancy.
- Lean body mass: The more muscle you have the less buoyant you will be. The inverse is also true, the more fatty tissue the more buoyant you will be. The distribution of that mass also affects your trim in the water. Generally, women have more fatty tissue in the lower part of the body making their legs more buoyant. Men generally carry their fatty tissue around their stomach, making that the most buoyant area.
- Water Salinity: More salt in the water the more buoyant a person will be. E.g. Dead Sea. A person will be least buoyant in fresh water.
- Wetsuit thickness: The thicker of a wetsuit you wear the more buoyant you will be. Also, a new wetsuit will be more buoyant than a wetsuit that has been used for 20 dives. A general starting rule for weighting, use 10% of your body weight with a 5mm wetsuit.
- Lung Volume: The larger your lungs the more buoyant you will become with a full breath.
- Arm movement: Using your hands to swim affects your upward and downward direction in the water. It may seem logical to use your hands to climb your way down the water column but this is counter-effective. Using your hands causes you to breathe in which causes even greater upward force, creating a vicious cycle of hand flailing. Stop using your hands, BREATHE OUT!
Neutral buoyancy and swimming position
The most comfortable position to be in the water is a horizontal position. It is more difficult to lower your diaphragm in a vertical position in the water. This is because the bottom of your lungs is in a greater pressure than the top of your lungs, it therefore takes more effort to lower your diaphragm. This increased effort raises anxiety and leads to the stress cycle. Break down the cycle where it starts, be aware of your breathing patterns and stress levels.
Buoyancy is the skill most often used in scuba diving. When you learn to scuba in the pool, you will learn to clear the regulator and clear the mask. These skills are not used half as much as you will be neutrally buoyant. You will be neutral the whole dive if everything goes well. Our instructors follow these training philosophies starting from your first pool dive.
Choosing to do your Open Water Course
Your instructor should introduce neutral buoyancy as early as possible. They should allow plenty time for you to practice your buoyancy in the pool, you should also get comfortable repeating all your skills in a neutrally buoyant position. When you are diving you are not going to sit on your knees to clear your mask, therefore it should be a skill you are comfortable doing while swimming.
PADI diver training is the top training organization in the world for a reason! Check this article on buoyancy from PADI
As mammals our natural instinct is not to breath under water. It takes some coaxing of our body’s to convince them that we actually have the ability to breath underwater with our equipment. It is our natural instinct to take a full breath in as soon as we hit the water to make ourselves more buoyant. We then over compensate for this extra buoyancy by putting on too much weight. We then have to add a lot of air to our BCD once at the bottom, this leads to more drag and increases our air consumption.
The “old school” of instruction
Instructors would add too many weights to students to allow them to sink, this was done to compensate for the natural instinct keep a lot of air in the lungs while scuba diving. It is important to identify this instinct in yourself, keeping your lungs full of air while breathing causes anxiety and leads to a stressful dive.
On your next dive take note of this reaction next time you hit the water. Take a few seconds to re-assess your breathing and ensure you exhale all the air from your lungs before reaching for more weights.
It is important that we protect coral reefs for our future. It may not look like it but the hard rocky surface, which looks dead, it actually a living organism which suffers when divers kick and kneel on them. Please perfect your buoyancy in a sandy area before attempting it over sensitive corals.
Follow these tips to revolutionize your diving experience!