A diver without good buoyancy is like a driver who is unable to change lanes, is uncomfortable reversing, and cannot parallel park. Not really a good driver, right? Mastering buoyancy is one of the most fundamental skills that you must learn and perfect to really be in control of your dive. This is our comprehensive guide to buoyancy, with eight tips for helping you improve your buoyancy control.
Scuba diving is not a competitive sport, but if it was, buoyancy control would be one of the main points of competition. Mastering buoyancy—that is, a diver’s ability to control her body movements, depth and position underwater—is the key to optimal scuba diving performance.
Buoyancy control is what prevents divers from falling deep into the abyss when diving in open water and from shooting up to the surface like a torpedo when ascending. It is what allows underwater photographers to get up close and personal with macro critters that hide beneath coral outcrops and it’s what allows cave and wreck divers to safely penetrate into overhead environments.
Because it is such an important skill, we’ve created this guide that will tell you everything you need to know about buoyancy control: what it is, why it’s important, and tips for improving your buoyancy that you can implement on your very next dive.
Advantages of Buoyancy Control
Good buoyancy control is what separates seasoned pros and experienced veterans from newbie divers, and it is the single most important skills any diver can master. Once a diver becomes a proficient practitioner of buoyancy, they reap a number of benefits:
Increased Safety: According to Diver’s Alert Network (DAN), overweighting and poor buoyancy are often contributing factors to scuba diving accidents. Good buoyancy reduces the risk of decompression illness by helping divers control their ascent and descent rates.
Protected Marine Environment: Divers with good buoyancy do not cause damage to delicate marine environments by crashing into rocks and corals. Instead, they glide effortlessly through them, taking in the sights as they go, zooming in close when they want to, and pulling out without leaving a trace.
Improved Air Consumption and Reduced Fatigue: Divers with bad buoyancy tend to flail around and move their limbs a lot. This causes them to exert a lot of energy and consume air quickly. By contrast, neutrally buoyant divers do not have to work very hard to maintain their position in the water, allowing them to conserve air and energy, and prolong their bottom times.
Better Diving Experience: Being able to control your movements makes each dive more enjoyable. Diving becomes a more relaxed activity, you can get a closer look at interesting marine animals, and it improves your confidence in your abilities.
Basics of Buoyancy
Before you can become a master of buoyancy you need to make sure that you understand the fundamental principles governing how solid objects interact with water.
Buoyancy refers to an object’s tendency to float, sink or do neither. In the case of scuba diving, there are three different types of buoyancy that are of importance; positive buoyancy refers to a diver floating upwards towards the surface; negative buoyancy is when a diver sinks downwards towards the bottom; and neutral buoyancy is when a diver neither sinks nor floats, but instead remains suspended in the water at the same depth level.
When you suit up, take a giant stride and jump into the ocean, your body displaces water. At the same time, the water surrounding your body has a tendency to try to fill in the space that your body now occupies. As a result, your body is pushed upwards by a ‘buoyant force’ equal to the weight of the water that your body is displacing. This is called Archimedes’ Principle.
According to Archimedes’ Principle, an object floats up if the weight of the water it displaces is more than its own weight. An object sinks down is the weight of the water it displaces is less than its own weight. Finally, an object remains suspended at one level if it is the same weight at the weight of the water it displaces.
From the very beginning of the Open Water scuba course, divers are taught how to achieve negative buoyancy for descending, and to strive for neutral buoyancy while diving at depth. Unfortunately, we cannot simply change from negatively to neutrally buoyant on a whim, so we use weights and a buoyancy compensator device (BCD) to help control our buoyancy.
How to Improve Your Buoyancy
Mastering buoyancy takes practice and is something a diver can work on for much of their diving career before perfecting. To achieve neutral buoyancy, scuba divers must achieve a balance among a number of factors that affect buoyancy: weighting, exposure suit, body position, breathing, equipment, and more. The following eight tips will help you to improve your buoyancy control while scuba diving.
Tip #1: Get Your Weight Right
Wearing the right amount of weight is the single most important factor when trying to achieve neutral buoyancy. You must think about all of the factors throughout a dive that will affect whether you will sink or float, including the type of exposure suit you will be wearing, the size of the cylinder, how deep you will be going, and more. Then you must choose the right amount of weight to compensate for the positive buoyancy of the each.
Many dive instructors overweight their Open Water students to keep them from making an early visit to the surface. This makes monitoring easy for the dive instructor, but can make students leave the course thinking they require more weight than they actually do. Overweighted divers need to compensate for extra weight by putting more air into their BCDs, making them more susceptible to erratic buoyancy shifts as they change depths.
The best practice is to use only the amount of weight you need. Each kilogram and pound should be justified. If you are unsure of how much weight you need, do a buoyancy check at the end of your dive to help achieve the optimal starting point for perfecting your buoyancy.
Tip #2: Know Your Equipment
The size and weight of each piece of dive gear influences your buoyancy. As a general rule, the heavier a piece of gear, the the more negatively buoyant you will be. The two pieces of gear that have the greatest impact on buoyancy—other than the BCD—are the type of exposure suit and air tank.
Wetsuits have tiny air bubbles contained within the neoprene material that make them positively buoyant. The thicker the wetsuit, the more buoyant it will be. With drysuits, a layer of insulating air gets trapped between the diver’s body and the suit, also causing positive buoyancy. It is also important to consider the thickness, age and condition of wetsuits, as they become less buoyant as they are used more.
The type of cylinder you use, steel or aluminum, and the size, will also impact your buoyancy. Steel tanks are generally more negatively buoyant than aluminum tanks. They will begin the dive negatively buoyant and then gradually become less negatively buoyant. Aluminum tanks, on the other hand, will have you floating up to the surface at the end of the dive if you are not weighted properly.
It is crucial that you know how your equipment affects your buoyancy, how it changes, and how much weight is necessary to compensate.
Trip #3: With the BCD, Less is More
While the rest of your gear maintains a constant weight and volume, your BCD is the one piece of your gear whose weight and size fluctuates throughout a dive. It can be inflated and deflated to change the amount of water it displaces. It is very important that you know how to use it, and that you use it properly.
When you descend, do so with an empty BCD. If you are properly weighted all you should need to do is exhale deeply to start sinking. As you descend from from a dive you must add air to you BCD to maintain neutral or slightly negative buoyancy. Do so i small bursts, to prevent over-inflation. As you ascend to shallower depths, make sure to release air from your BCD to maintain depth control and stay neutrally buoyant.
When you are properly weighted, you shouldn’t need to use your BCD very much. In fact, being over-reliant on adding air to your BCD can be dangerous. It puts you at risk of a rapid ascent and also means bigger buoyancy shifts as you change depths, because the size of the air bubble in the BCD will grow or shrink rapidly each time you ascend or descend.
Tip# 4: Assume the (Trim) Position
Maintaining the correct body position while underwater is also of paramount importance to achieving good buoyancy. Divers who have control of their buoyancy are able to glide along in a smooth, horizontal position, with their body completely flat and steady, knees bent 90 degrees, and fins pointing backwards. Combined with proper finning techniques, diving in this position will ensure that each kick propels the diver forward, not up or down.
Some divers may find it difficult to maintain a completely prone body position. This is most likely because their weight is not distributed properly. Traditional weight belts center all of the weight around the diver’s waistline while the buoyant force from the BCD is concentrated near the shoulders. This causes the diver’s shoulders to be pulled to the surface while the waist is pulled downwards. It may be necessary to play around with your gear configuration to find the optimal position for your weights. For example, backplate and harness BCDs better distribute weight among the wearer’s torso. Also, steel cylinders are useful for moving your center of gravity higher up your body to balance the buoyancy provided by the BCD.
Tip #5: Be Aware of Changes in Time and Depth
During a dive, you become more or less buoyant based on how deep you are and how much time has passed. It is extremely important to be aware of these buoyancy shifts caused by changes in depth and time, so you can act accordingly to adjust your buoyancy.
First, as you descend at the beginning of a dive, the buoyancy from your exposure suit lessens as the bubbles within the neoprene become compressed. The gas spaces in your body also compress at depth, further reducing your buoyancy. You must compensate for this loss of buoyancy as you descend by adding air to your BCD and releasing air when you ascend to maintain depth control and stay neutrally buoyant. Don’t forget that you have air in your BCD! The more air you have in your BCD at depth, the more you will have as you ascend. If you do not vent air from your BCD as you ascend, you may end up skipping your safety stop and risking decompression illness in the process.
Second, as each dive progresses, your tank becomes lighter because it has less air in it. Therefore, it is more positively buoyant near the end of a dive than at the beginning. This is a buoyancy shift of several kilograms that must be compensated for by venting air out of your BCD. It is one of the main reasons why we must start a dive heavy with weight.
Keeping in mind the predictable changes in buoyancy that take place throughout a dive is necessary to maintaining good buoyancy.
Tip #6: Use Your Lungs
Your lungs can be used as a natural buoyancy compensator device for fine-tuning your buoyancy. When you are neutrally buoyant you can rise and fall simply by controlling the amount of air you breathe in and exhale from your lungs, without having to inflate or deflate your BCD.
If you find yourself rising away from the bottom, simply exhale all the way to empty your lungs and you will become negatively buoyant. If you find yourself too close to the bottom, take a deep breath to rise a bit. Make sure not to hold you breath as you rise, as this could lead to a lung over-expansion injury.
Tip#7: Keep Calm and Dive On
Staying calm and relaxing during each and every dive is crucial. Newbie divers who are very nervous and anxious tend to breath rapidly, causing them to consume their air quickly and to float uncontrollably. By staying in control of your breathing you can observe how your body reacts to each inhale and exhale.
Tip #8: Log it
Mastering buoyancy is essentially achieving the perfect balance of a number of variables that affect whether you float or sink. Recording the information from each dive in your dive log so that you know which combination of variables works under different water conditions helps you make adjustments when you dive at different locations. By using your dive log as a learning tool, you can help identify the skills you need to work on and track progress towards achieving your goals.
Practice Makes Perfectly Buoyant
As with most things in life. Practice makes perfect. The best way to improve your buoyancy is to get into the water and dive as much as you can. Pay attention to the equipment you wear, the type of water you dive in, and how much weight you need. Analyze your breathing to get a feel for how it effects your buoyancy. Eventually, buoyancy control will become second nature to you, just like changing lanes while driving.
– Ryan Patrick Jones, Contributing Writer