What is a Buoyancy Control Device (BCD)?

You just got your Open Water Diver certification and you are ready to dive into the big, wide world of scuba diving. But before you do, there are a few pieces of essential gear that you need to get first. One of those pieces is a Buoyancy Control Device (BCD). So, what exactly is a BCD and what does it do?

This article will give you the skinny on all things BCD and shed some light on this mysterious piece of gear that will be an essential part of your dive equipment collection.

🤿 1. Why Do We Need a BCD Device When Scuba Diving?

BCD stands for Buoyancy Compensator Device, and some folks are known to call it a Buoyancy Control Device, or Buoyancy Compensating Device.

In short, a BCD is like a life jacket for divers, helping you control your buoyancy while scuba diving. This is important because if you are too buoyant, you will float to the surface and if you are too heavy, you will sink to the bottom.

Your BCD will help you maintain your position underwater, preventing you from ascending or descending too quickly.

divers near reef

The BCD is also what your tank is attached to. Without it, you’d be sinking with your tank!

Of course, your weight system also plays a part in controlling your buoyancy. Your BCD and weight system work together to keep you perfectly neutral, helping you use less energy and maintain more control, which is the main goal for every diver.

In addition, a fully inflated BCD at the surface will help you stay afloat and swim backwards, saving precious energy for the next dives.

🛠️ 2. How Does A Scuba BCD Work

Think of it as a jacket that you can pump air into, to control your buoyancy.

A BCD provides positive buoyancy when required and adjustable negative buoyancy at other times.

The amount of air in a BCD is controlled by the inflator hose, a device hooked up to the first stage that pressured air can be pumped into.

This is controlled by the diver, who uses either a button or knob on the device to control how much air goes into it. Breathing into it also fills the bladder.

Divers getting ready for scuba diving

👉 3. How Do You Use A BCD

The BCD is strapped onto the scuba cylinder, also known as the tank, and the tank goes onto your back in a system called the back mount.

The inflator hose is hooked up to the BCD, allowing you to use air from the tank and pump it into the BCD through the inflation valve. Needless to say, you add air into the BCD through the inflator hose, you’ll float, and when you release air, you’ll sink.

The diver needs to ensure that he or she has proper weighting and that tanks do not get in their way. A poorly weighted diver will constantly be struggling with buoyancy control, causing much stress and adjustments during the dive.

Buoyancy control is the key to floating gracefully underwater with minimal effort as opposed to constantly bobbing up and down like a yo-yo.

Keep in mind, too much air in the BCD during the dive and you will be swimming around like the Michelin man and create a bunch of drag during the dive.

A BCD can have two or more inflation and deflation valves on the top of the unit so that air can be added to inflate the bladder and make the diver positively buoyant.

Or, air can be released from the bladder to deflate it and make the diver negatively buoyant, allowing you to fine tune your buoyancy during your dive.

On the surface, a fully inflated BCD will help with flotation and keep you buoyant.

📊 4. Types Of Scuba BCDs

Recreational diving uses two main types of BCDs – jacket, and back-plated.

Jacket Style Buoyancy Control Device

This is the most common type of BCD and the main way to teach, making them a staple piece of gear for any dive center or dive resorts.

A jacket style BCD is built for comfort and is the most popular choice, whether for the novice or experienced diver. These BCDs are worn precisely as their name indicates – as a jacket!

Chuck it on just like you would a jacket with adjustable shoulder straps. A cummerbund and waist strap buckles at the bottom front while the diver’s chest is secured with a chest strap.

Jacket style BCD can also hold integrated weights. More on that to come, but quickly put, an integrated weight system has weight pockets that are built into the BCD that you can ditch in an event of an emergency. This takes the place of a separate weight belt.

One of the main advantages of a jacket BCD is that it is very comfortable to wear. It also provides a lot of buoyancy, which makes it easier to stay afloat. Additionally, a jacket BCD is very easy to use and can be quickly inflated or deflated.

Keep in mind, too much air in the jacket style BCD and your torso will be pushed upwards, resulting in a worse trim.

In addition, a jacket style BC will help float an unconscious diver face up on the surface. This brings us to the back inflate BCD.

Back-Plated Buoyancy Control Device

Experienced divers seem to love the back inflated BCDs! They are certainly a favorite for cave divers.

A back inflate BCD typically has a balloon-like structure at the diver’s back called the air bladder. Between this and the buoyancy chambers, there are usually straps that allow for adjustment.

One of the main advantages of a back inflated BCD is that it provides enough buoyancy to keep an average-sized person afloat while using a minimal amount of air.

This benefits divers because they have to carry all their buoyancy compensators on their person and travel relatively light when diving.

In addition to the usual straps that allow for easy adjustment by the diver, a back-inflated BCD can come with shoulders, and crotch and leg straps in a harness type design.

Back-inflated BCDs also are known to give more buoyancy control and allow for better trim. While buoyancy is whether you float up and down, trim is the position of your body throughout the dive. Simply put, the better the trim (aka, swimming more horizontally), the less effort you’ll spend when you swimming.

Back-inflated BCDs have bladders of different types and sizes so make sure you pick one appropriate to your body weight so your BCD helps with flotation and you can easily stay buoyant when on the surface.

One of the main disadvantages known about back-inflated BCDs is that when on the surface, these BCDs have a tendency to push your face down, making it not very pleasant for an unconscious diver.

This safety fault, although rare, is one of the biggest drawbacks of back inflated BCDs.

All BCDs come with dump valves, or purge valves, to quickly dump air if you have to be negatively buoyant quickly. Some divers are known to use a purge valve on descent.

Most BCDs also come with D rings to attach other scuba diving equipment to like alternate air sources, SMBs, and reels.

Back-plated buoyancy control device

⚖️ 5. Weight Belt Or Integrated Weight System?

As previously mentioned, some BCDs have weight pockets that are slotted into where normal pockets are. These are removable and can be easily pulled and ditched in an event of an emergency.

An integrated weight system on a BCD takes the place of the traditional belt. Keep in mind, with integrated weights, you’ll be lugging around more weight so make sure to pick a weight integrated bc with proper lumbar support based on your torso length, size, and body weight.

Also check that the weight pockets don’t affect your horizontal trim which will create more drag and take more effort.

🔍 6. Picking A BCD

Of course, all things are a personal preference. First, decide on whether you want a jacket style BCD or one that back inflates.

Once you do, the design, weight, and buoyancy of the BCD all play an important role in how it feels underwater. For example, a diver wearing a BCD will also be affected by where the air sits and the effect it has on trim.

Try several brands and see what works for you.


Of course, you don’t want something that will break the bank. BCDs have a huge range of prices, and back-inflated BCDs tend to cost a bit more than minimalistic jacket style BCDs. Most recreational divers get away with paying about US$500 to $1000 for a BCD.

Lift Capacity

Lift capacity is the amount of weight that a BCD can support with fully inflated. The appropriate amount of lift depends on the diver’s torso length, size, shape, dive conditions, and gear.

Whether diving in a dry suit or thick wetsuit with 30 pounds of weight or in the tropics with 2 pounds and a neoprene foam shortie, your BCD must be enough to allow you to float comfortably on the surface. If you need extra buoyancy, go for a BCD that is capable of larger lifts.


Whether you want a weight integrated BCD, more pockets, a cummerbund other features will also help you narrow down your choices. If you expect to dive in a variety of conditions, a more generic model might be suitable.

However, if you are primarily looking at specialized dive gear like that for cave or wreck diving, you can consider back inflated BCDs.


If you are expecting to travel on a regular basis to dive, a travel BCD would be your best bet. There are numerous models of ultra lightweight, minimalistic BCDs for the folks that travel to go diving.

Keep in mind that back inflated BCDs often have a steel or aluminum backplate that can weigh more.

✅ 7. Taking Care Of Your BCD

Like everything, your BCD needs some lovin’ just after the dive. Always clean your BCD in fresh water after the dive.

  1. Dunk your BCD in fresh water to get the exterior clean of any sea water or sand
  2. Fill the air bladder with fresh water and swish it around, cleaning the interior
  3. Drain the BCD of water, and if you want, give the inside a second rinse
  4. This will help get the rest of the salt water out.
  5. After your BCD has been rinsed, fill the air bladder with air and hang it out to dry in a shaded area
  6. Never put your BCD in the sun or near a heat source. Direct sunlight or a heat source could break down the material in the BC or turn it brittle, compromising its durability.
Buoyancy control device floating on water

💭 8. Final Thoughts On BCD Scuba Equipment

In the world of scuba diving, Buoyancy Compensator Devices go by many names. One way to know if this is right for you? If your next trip involves deep-sea diving adventures, then yes!

Your BCD will be an essential piece of equipment right up there with your regulator set. We hope this article makes you more aware of what this piece of scuba diving equipment does and how to use one. Of course, nothing beats professional advice so go to your dive center and chat with them.

Thanks for reading, and happy diving!

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