The buoyancy compensator, or buoyancy control device (BCD), is one of the most important pieces of diving equipment. A diving course gives you the basics, and if you haven't finished one yet, you will certainly get the chance to try a BCD there and talk it over with your instructor.
What a BCD is for
A BCD does many jobs:
- Controls your buoyancy. This is its main job: it gives you the buoyancy you need during the dive and keeps you afloat on the surface when you are not diving.
- Holds your cylinder.
- Carries your gear. All your other diving equipment attaches to it.
- Carries weights. Many BCDs have an integrated weight system.
Kinds of BCD
When choosing a BCD, think about the style or kind of diving you plan to do.
Jacket style
The most common design: fairly simple and popular with divers. The air bladders are spread evenly over almost the whole jacket.
- Pros: a very stable position on the surface and neutral buoyancy at any depth.
- Con: when fully inflated, it squeezes the diver noticeably and can restrict movement a little.
Back-mounted (wing style)
The air bladder sits behind your back and looks a little like a wing, hence the name.
- Pros: it doesn't restrict your movement, and it is easier to stay horizontal during the dive.
- Con: it is harder to stay upright on the surface, for example when you have to wait a long time for the boat to pick you up after a dive.
This kind is more often chosen by underwater photographers and by divers who go deeper or plan to use more than one cylinder.
Advanced design
These BCDs try to combine the good points of the two designs above.
Backplate and wing
This kind of buoyancy compensator is used by technical divers. The plate is made of stainless steel, aluminium alloy or carbon fibre. The wing, the harness and usually twin cylinders are attached to it.
Such systems are becoming more popular with recreational divers too: wings come in various sizes, and a single cylinder can be mounted as well.
Integrated weight system
Many modern BCDs have an integrated weight system. It helps avoid overloading your lower back and spreads the weights evenly. Many divers combine such a system with a weight belt, while some very conservative divers use only a belt and avoid integrated weights.
In our view, integrated weights are a good choice. If you look after your BCD, the chance of losing weights during a dive is minimal. And if it does happen, losing one pocket means losing only part of your weight, not all of it as with a lost belt. You are then likely to keep your buoyancy under control and, with your buddies' help, reach the surface safely. We write more about weights in a separate tip.
Lift
| Diving | Lift |
|---|---|
| An average recreational diver's dives | 9–18 kg is usually enough |
| More demanding conditions, more equipment, technical dives | usually 18–36 kg |
How to choose and check a BCD
- Decide what kind of diving the BCD is for, and choose its type and lift accordingly.
- Choose the right size. Remember that you will wear the BCD over your suit: it should sit comfortably on your body.
- Inflate the BCD fully until the overpressure valves release. Fully inflated, it must not restrict your breathing.
- Check that you can reach all the dump valves and buckles, and that you can operate the inflator with one hand. Most BCDs have several dump valves, which is handy.
- If you can, dive with different BCDs before you buy: it will help you find the right one.
Choose quality
A BCD is not a one-day purchase: with proper care it will serve you for a long time, so it is worth choosing a really good one.
You can try BCDs on in our shop in Vilnius or choose one online.
Frequently asked questions
What is the difference between a jacket and a wing BCD?
A jacket BCD has its air bladders all around the jacket: it is very stable on the surface, but squeezes you when fully inflated. A wing BCD has its bladder behind your back: it doesn't restrict your movement and helps you stay horizontal, but it is harder to stay upright on the surface.
How much lift do I need?
For an average recreational diver, 9–18 kg is usually enough. In more demanding conditions, with more equipment and for technical dives, BCDs with 18–36 kg of lift are usually used.
Are integrated weights safe?
In our view, yes. If you look after your BCD, the chance of losing weights is minimal, and if you lose one pocket you lose only part of your weight, not all of it as with a lost belt.