The Underwater World

Buoyancy

You control your buoyancy using two pieces of equipment. These are lead weights and a buoyancy control device (BCD). You will want to purchase these items as soon as possible. You use lead weight in a weight system (such as a weight belt or in a weight integrated BCD) to adjust your weight. The BCD is a device that you inflate (increases your volume) or deflate (reduces your volume) thereby changing your buoyancy at any time during a dive. During the confined water dives, you'll learn how to start a dive with the right amount of lead weight, and how to adjust your buoyancy as you need to using your BCD.

Since buoyancy results from the weight of water volume displaced, the heavier the water, the greater the buoyancy for a given displacement. Salt water (due to its dissolved salts) weighs more than fresh water, so you're more buoyant in salt water than in fresh. Without any gear on, most people float in either fresh or salt water. When floating motionless at the surface, most people need to exhale to sink.

When you exhale, you decrease the volume of your lungs and the amount of water you displace, which makes you, less buoyant. You'll discover during the confined water dives that in addition to using lead and your BCD to control your buoyancy, you can fine-tune your buoyancy by breathing more deeply or more shallowly.

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Dive Equipment Equipment Identification Fins Give Preview Introduction Padi Open Water Pressure and Your Body Regulators Scuba Systems

Scuba Tanks SnorkelsSubmersible Pressure Succed Course The Effects of Increased Air Density The Effects Pressure The Underwater World The Buddy System Valve Types