Difference Between Scuba Diving BCDs
I am often asked by students and other divers why I choose to use a backplate and wing rather than a jacket or even a back inflate BCD. So I figured I would address the differences by writing a blog post.
As you may or may not know, the BCD (Buoyancy Control Device) is an integral part of your scuba diving equipment. Not only does it hold your tank firmly on your back while you dive, but it helps you control your buoyancy by adding small bursts of air into it when you are at depths and releasing the air as you become more buoyant (changes in depth, buoyancy characteristics of the tank, etc), and it helps you float on the surface (all things covered during an open water scuba diver course).
If you’re looking at purchasing your first BCD, all the different kinds might be a bit overwhelming. There are jacket style, back inflate, back plate/wing setups. Enough to make you just pick the first thing the salesperson tells you is the latest and the greatest. Well, hopefully with this blog post, you will understand a bit more about the different kinds.
Jacket Style BCDs
Jacket style BCDs are the most commonly found type of BCD in dive center rental stocks. They are somewhat big and bulky, but when the diver adds air to them, since the bladder basically wraps around the diver, there will be air in the front, sides and back. This makes it extremely comfortable for a lot of people, and it is very comfortable when floating on the surface. Also, since the air is basically all around the diver, it is quite easy to deflate these types of BCDs, Plus the generally have big pockets to put an extra mask, slates, or other stuff that might come in handy (remember, never take anything while diving – except for trash).
However, as they are usually bulkier, they tend to create more drag, and since they have more padding, they require more weight to sink due to their inherent buoyancy. Also, if it is isn’t fitted properly, these types of BCD will alter a diver’s body position underwater, putting them in a slightly feet down, head up position (due to the air traveling to the highest point), which can sometimes make it more difficult to achieve that perfect trim that divers want.
So make sure that if you are using a jacket style BCD, it is fitted properly (not too big and not too small!).
Back Inflate BCDs
On a back inflation BCD, the bladder is only behind the diver, there is nothing wrapping around the diver. These type of BCDs are inspired on the back plate and wing setups, but they’ve been made more “user friendly” if you will. So as I said, the air bladder is behind the diver, then you have your shoulder straps coming out from it, on the waist you have a cummerbund which may or may not have integrated weight pockets, and utility pockets.
The benefits of these type of BDCs is that since the air bladder doesn’t wrap around the diver, there isn’t that feeling of being squeezed like there may be on jacked style BCDs. Also, they are generally more streamlined, which allows the diver easier movement in the water. Usually, back inflate BCDs have trim weight pockets which allow the diver to put some of the weight (non-ditchable) behind them, and that will in many (not all) cases help the diver obtain a better, horizontal trim.
Some folks claim that back inflate BCDs will throw you on your face on the surface when inflated. While that may be true to some extent, it only really happens if you over-inflate your BCD. The reason for this is that all of the air is on your back rather than around you like in a jacket BCD. However, if only enough air is put into it to keep you on the surface comfortably, then no issue should be had. Since these are still fully recreational BCDs, you should expect lots of padding, which makes the inherent buoyancy on them while not as radical as on a jacket style BCD, still pretty noticeable.
Back Plate and Wing Setups
For years people thought of these setups as “tech only” setups. And while yes, any technical dive who is diving in backmount will be diving one of these setups (although with a larger wing), for many years we have been using them for recreational diving as well.
These setups are minimalist by design. My personal favorite is the Hogarthian design. Without getting too deep into the details, it is a design by Bill Hogarth Maine, who in the 1980’s came up with a minimalist approach to cave diving. Wait!?! Cave diving, you say? Remember what I said before… For many years this setup has been adapted into recreational, single tank diving as well.
Anyways, this setup is made up of a stainless steel or aluminum back plate, the harness is a single piece of 2″ nylon webbing (same as the weight belts) that is woven through the back plate, 1 d-ring on each shoulder, and 1 d-ring on the left waist band, a crotch strap, a back mounted air bladder (wing – 20 to 30 lbs lift max) and that’s it. No pockets (though utility pockets can be added), no padding, nothing else.
Ok, so what’s so great about this? It sounds horrible! Well, it is actually super comfortable. Plus, the fact that this type of setup is completely negatively buoyant, means that you need to carry around less weight on a weight belt. You can add weight pockets to these setups, but me personally, I don’t need any weight in salt water with my setup, so it is perfect. Since all the weight is on your back (a steel plate weighs around 6lbs, and an aluminum 4lbs), and the air bladder is also on your back, it helps you maintain that perfectly horizontal trim (obviously, it is not a magic bullet. Practice is required!). There are some other harnesses that are adjustable and have some padding, but I personally like the minimalist style. Also, if/when the harness wears out, I just buy a length of webbing (super cheap), and make a new harness.
The cons of this type of setup is that to set it up, it does require some some assembly since they are modular systems, and may require some help to set up properly. But once you’ve done it once, if you ever need to do it again, you can probably do it yourself with just the help of a mirror. Also, some people may not like that there are no pockets on these systems. Me personally, I have a leg mounted utility pocket that works wonderfully to carry my extra mask, slates and other safety items I carry.
I hope I was able to clear up some of the differences between the most common types of BCDs out there. Remember, you should always seek proper training prior to attempting to use any scuba diving equipment, and if you buy used equipment, have the gear inspected and serviced by an experienced, certified and qualified service person prior to using it. After that, schedule some time in the pool to test it out and get used to it. Never try out brand new gear on your diving vacation. That is a recipe for disaster, and we will cover that in another blog.