The Complete Guide to Scuba BCDs (Buoyancy compensator/control device)

The Complete Guide to Scuba BCDs (Buoyancy compensator/control device)

This article is another addition to our “Complete Guide to…” series. This series is where we discuss each part of your scuba diving equipment and tell you, well, “everything you need to know.” Today we are going to be discussing the critical but confusing BCD. Let’s start with the basics.

What is A BCD?

A BCD is a critical part of your scuba diving gear. It gets worn like a jacket or a vest with the most essential scuba diving equipment, such as the tank, attached to the back. Your oxygen tank connects directly to the BCD via a power inflator and is wrapped around your body. You use the BCD to maintain proper buoyancy in the water.

When we say “everything you need to know,” we quite literally mean everything, so this is going to be a thorough deep dive into buoyancy control devices for scuba diving. If you are curious or perhaps a new scuba diver, you have come to the right place.

Let’s get into the article…

(I’ve got to stop saying “let’s dive in” (damn it, said it again!))

When you are scuba diving, you need a BCD to control your buoyancy.

When you are still on the surface of the water waiting to descend or relaxing after a dive, a BCD provides positive buoyancy. If you did not have a BCD, you would have to tread water.

The heavier your gear is, especially your weights, the more you need positive buoyancy, and thus the BCD is there to help. It is essential to remember that while you are diving, there will be constant buoyancy changes due to pressure.

While you are descending, you usually make slight adjustments to your buoyancy by adding air into the bladder of the BCD. Remember, your wetsuit loses buoyancy the deeper you go because it compresses.

While you are coming up to the surface, the air in the BCD starts to expand; therefore, you need to release some of that air to avoid a dangerous rapid ascent that could possibly cause the bends.

How Does a BCD Work?

A BCD works with your oxygen tank. It is connected directly to the tank with a power inflator. This power inflator takes oxygen from your cylinder through a hose and into the bladder of the BCD. The diver controls this with a button close to the inflator.

If your power inflator fails, each BCD has a safety feature that allows you to blow air into the bladder manually. So, don’t worry too much about the BCB failing in this regard.

Each BCD should have one or two relief valves. These valves are used to expel air from the bladder without allowing water to fill up the bladder. 

Scuba diving equipment on the boat

3 Main Styles of BCDs

Before you go out and get a BCD, it is essential to note that there are three main styles. None of them have many advantages over the other. Instead, it is more about aesthetics and also comfort. What suits you may not suit someone else and vice versa.

With that said, the minor differences are important.

The Jacket

The BCD jacket is the more traditional style. It is called a jacket even though it has no sleeves and resembles a vest. You can quickly tell the jacket BCD apart from any other type as it kind of looks like a racing car seat from a distance.

When you look at the jacket BCD, you can see that it is designed almost to wrap around you to keep you stable.

The main advantage of the jacket BCD over the others is that it is more user-friendly. So, if you are new to diving, I recommend using a jacket Style BCD. Here are a few reasons why the jacket style BCD is more friendly for beginner divers.

  • Bulkier sides help keep you orientated and upright.
  • The bigger BCD makes carrying the rest of your equipment more accessible.
  • They often have an integrated weight system (in most cases).
  • Attaching your tank is easier.

The Semi-swing

The semi-swing is more like a backpack than anything else. It offers a lot of freedom of movement for a diver, which means that it might sound better. However, this kind of BCD is only used by more advanced divers.

The Backplate

The backplate design also resembles a backpack, albeit a small one. It has one job only, and that is to act as a buoyancy control device without any other added features.

The reason for this is the backplate is designed with the technical and commercial diver in mind. It is minimalistic because a specialised diver would prefer to customize their setup to suit their job. What better way to achieve this than by offering a simple bladder with the option to have it customized.

If you are a beginner or intermediate diver, we do not recommend going for the backplate design.

How important is a BCD?

When it comes to pretty much all of the scuba gear, they work together. When we discuss the importance of that gear, saying that one is less important than the other doesn’t mean you don’t need it. Instead, what we mean is you don’t have to spend as much on that item as you do on others.

With that said, a BCD is critical to your scuba gear setup. Without proper buoyancy control, you can find yourself in some tricky situations. 

What I’m trying to say is, if there’s one piece of equipment you shouldn’t scrimp on, personally, I’d never buy a second hand one. When it comes to my life, I want to know the history of potentially lifesaving equipment.

How Should a BCD Fit?

For a jacket and a semi swing style, you want them to be snug and comfortable but not too tight. The jacket should not dig into your skin or your wetsuit. If it does dig into your skin, this could be uncomfortable and cause damage to your wetsuit.

Finally, you don’t want a BCD to rise on your body when you fill it with air. This generally happens if the BCD is too big.

How Much Does a BCD Cost?

For a good quality BCD, you can expect to pay around $350 to $500. While this may seem like a lot at first, it is essential to remember that this is an integral part of your safety equipment while doing an activity that requires some precaution.

As I said earlier, you shouldn’t try and cut corners when buying a BCD.

Remember, you are constantly allowing air in and out of the bladders. When you are ascending, there are times where the air expands before you have enough time to release some of it. This expansion causes stress on the bladders, so you want a high-quality BCD.

How Long Does a BCD Last?

The average lifespan for a high-quality BCD is around eight years. This is excellent news because, as we discussed above, it is not the cheapest piece of equipment in your scuba gear setup. It is important to remember that this lifespan can be shorter if you do not properly maintain the device, and it can be longer if you take extra good care of it.

Scuba diver and a huge group of fish

How to Clean Your BCD: 5 Easy Steps

  • Rinse With Fresh Water
  • Place in a Freshwater Tub
  • Clean The Power Inflator and Bladders
  • Let it dry out
  • Inspect the BCD

Maintenance and cleaning are something that you have to do. It is the best way to prevent malfunction and make sure that your equipment lasts as long as possible, so in the section, we’ll give five easy steps to effectively cleaning and maintaining your BCD.

1. Rinse With Fresh Water

Before you start the cleaning process, you want to lay the BCD down on some grass or preferably hang it up outside. You then want to take a freshwater hose and spray the BCD with medium intensity. This preparation is going to get most of the saltwater or even chlorine off of the device.

2. Place in a Freshwater Tub

Once you have adequately rinsed the BCD, you want to soak it in a freshwater tub. Don’t use a swimming pool for this process because it is filled with chlorine and defeats the whole object. A bathtub is actually perfect for this.

Please don’t use soap in the water but instead get yourself a good quality scuba gear wash

Now, Gently wash the outside of your gear. Do not scrub too hard.

3. Clean The Power Inflator and Bladders

For some, this may be pretty scary, but you do need to clean the inside of the BCD bladders and the power inflator. The best way to do this would be to use a freshwater hose. However, a nice trick is to use a shower by disconnecting the showerhead. Be sure not to use warm water.

You are basically going to flush the power inflator while holding down the inflate button that usually allows air from a cylinder into the bladder.

Once the bladders are filled with water, you want to give the BCD a gentle shake just so that the water inside it cleans the entirety of the bladder.

You can use the pressure release valve to get rid of any water left in the bladders. Remember, try not to leave any water in there because you need as much space for air as possible.

4. Let it dry out

Your next step is to allow your BCD to dry out. For me, the best method is to hang the BCD in the shade. I understand that it can be pretty tricky, but you don’t want it to be left outside in the sun, but it still has to be out to dry, and you want fresh air circulating the device. So, hang it up in the shade if you can.

5. Inspect The BCD

The final step of this mini service is to inspect your BCD. It would be best if you were as thorough as possible. Remember, you want to check for any cracks or leaks. This is the first part of your inspection.

Once you have gone through an inspection, you want to inspect every component of the BCD to check that it is all working as it should.

Don’t Forget Your Dive Insurance!

Before you go out on any dive trip or holiday, it is essential to make sure you have insurance that covers you if something goes wrong. Check out our dive insurance article for more information.

Or go straight to these dive insurance company websites:


Diver Alert Network (DAN)

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Final Thoughts

Understanding how your scuba gear works is of the utmost importance. Hopefully, after reading this article, you now have enough information to buy and maintain your BCD.

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Paul Fulbrook

Paul Fulbrook is a writer, scuba diver, ex-science teacher and marine biologist. He has a passion for coral reef biology, diving on coral reefs and writing about diving. He also loves cats and his children (sometimes).

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