Buoyancy Control

Neutral buoyancy

Whilst scuba diving you want to be able to have full control over your position in the water, so much so that you can stably remain in the one spot. This is called neutral buoyancy, where you neither sink nor float. It is not as easy as it looks but once it is learnt, skills in buoyancy will help you get the most out of your scuba diving experience.

Why is neutral buoyancy so important

Keeping good buoyancy will allow you to direct your body with much greater ease so that you can be careful not to damage plant and animal life whilst swimming gently through the water. You will be much quieter as you aren’t thrashing about in the water trying to regain control. You will be able to approach and swim alongside sea life without startling them. Good buoyancy skills help you to avoid dragging your flippers across the sea bed, which again can cause damage and reduce visibility as you kick up silt.

Controlling your basic positioning in the water is the first step of buoyancy. Once you have a firm grasp on this you can learn more advanced manoeuvres which will optimize your scuba diving experience. You will be able to hover just above the seabed and in front of sea life on close observation, swim alongside sea life and safely manoeuvre in spaces such as shipwrecks. Less oxygen is used when neutral buoyancy is maintained; prolonging the amount of time spent exploring.

Buoyancy control device (BCD)

The primary piece of equipment utilized for buoyancy is called a buoyancy compensator (BC) or a buoyancy control device (BCD). There are 3 types of BCDs.

• Wings are two inflatable bladders that are attached to either side of the divers back. These can inflate to large volumes and therefore have high buoyancy.
• Stab jackets are vests worn in the upper part of the diver’s body and inflate either the back and side or the back alone.
• Divers lifejackets are generally cheaper and lighter then wings or stab jackets but they are also comparably uncomfortable and less buoyant.

How does one become neutrally bouyant? Role of BCD

To be neutrally buoyant, the weight of the water that the diver is displacing equals the weight of the diver themselves.

• If the diver is sinking, they are too heavy and the BCD needs some inflation by gas to increase the diver’s buoyancy.
• If the diver is floating, they are too light and gas needs to be removed from the BCD to reduce the diver’s buoyancy.

The role of BCD equipment in ascent & decent

The altering of the gas in the BCD isn’t just used for staying neutrally buoyant. It is used to go higher, lower and very important for a controlled ascent and descent. In away the BCD is used to apply brakes.

• During decent gas is actually added to the BCD so that the fall of the diver is not too fast resulting in them hitting the seabed floor.
• During ascent gas is released so that the diver is not buoyant to the extent that ascent is not too fast and unsafe.