At some point, I can’t quite remember when, someone, somewhere decided to have a BCD war. Mine is bigger than yours so mine is better. The next day his was bigger than mine and so on until we all arrived at BCD’s with some amazing and ridiculous amount of lift. This war spilled over to the general diving community and people were told the more lift the better the BCD. Manufacturers made bigger BCD’s and then, through marketing, told everyone they needed them.
Are Heavier BCD’s Necessary?
Being a diver who has spent time in both cold (under ice) and tropical waters, my observations are far from limited to one area of diving. I had a discussion once with a diver who did most of his diving on North Atlantic wrecks. He was in one of my buoyancy classes and made it very clear that my ideas probably worked well in warm water but for his type of diving a BCD with 65 pounds or more of lift (that’s what he said!) was necessary. Asking why, he explained because of the heavier equipment worn and heavier wetsuits. He also explained that his kind of diving used twin steel 90’s or 120’s and with all that weight, plus 2 heavy knives, lights that sink plus a few other odds and ends and X pounds of lead, 65 plus pounds of lift was necessary.
Let’s examine this a bit closer. Are these divers with all this heavy equipment, which is apparently already dragging them down, wearing additional lead on a belt? If so, why? If I put weight on my back (e.g. heavy tanks) then some amount would come off the weight belt. If I leave my knives and lights home, perhaps use an aluminum tank, then I would add some lead. But to add both weighty equipment and then lead to the belt is counterproductive.
One of the primary objectives of good diving is to get as neutral as possible. Pure neutrality is quite impossible though, because of numerous factors such as breathing, wetsuit compression/expansion and the tank gets lighter with each breath taken. But getting close is what a good diver strives towards. With that in mind, why would someone make themselves so negative that they would need 65 pounds of lift? Or even 50 or 30 for that matter. The only explanation would be, for example, a diver who actually needs 28 pounds of lead but wears 58, so a BCD with at least 30 pounds lift would be needed just to get neutral.
Wetsuit compression
Wetsuit compression always enters into any discussion about cold water BCD’s versus tropical. This is pointed out quickly in any argument for those who wear oodles of lead with inflatable boats strapped to their backs. Wetsuits do compress but not to the degree that the kind of lift some claim is necessary. Again, I wear a heavy wetsuit (I have even worn a full hooded farmer john in tropical water) as do some of my staff, and none of us, no matter what depth (even very deep) have any trouble with buoyancy. Nor do we put air in our BCD’s to compensate. I can see the reason some people do need to overcompensate with a BCD. They are so overweighted that they would be walking on the bottom. Instead, they inflate the BCD and more or less walk through the water because of all the air lifting them at the top. So where is the argument about wetsuits?
A friend of mine completed his second diving expedition to Antarctica. He wore a total of 50 pounds of lead. No BCD’s were worn at all. The 50 pounds made him “neutral.” No need for 65-pound lift BCD’s. And that has got to be some of the most extreme diving there is.
There was an article in a well-known dive magazine which was about selecting a BCD. It said something to the effect that one should choose a BCD with 10 or so pounds more lift than the total weight worn. As an example, it said a diver who wears 30 pounds of weight should have BCD with at least 40 pounds of lift. I read this twice to make sure I understood and wondered why a diver would wear 30 pounds if it made him 30 pounds negative? 30 pounds should make him close to neutral negating the lead. So, a BCD with just a little lift would be fine.
Why I never put air in my BCD underwater
I never put air in my BCD underwater. I use my BCD for 3 reasons only. One, it is great way to keep a tank on my back. Two, it meets a requirement of not diving without one and three, the most important, it makes a great surface flotation device. And that is what it should be, an SFD. A true buoyancy compensation device would be designed completely differently.
Generally speaking, the less buoyant part of our body is from the waist down. Where do we put weight? On the waist. The more buoyant part of our body is from the waist up, the lungs. Where do we put air for buoyancy compensation? At the top. Because of the design of a BCD this air is always at the highest point. Our equipment is making us stand up in the water. It is all backwards.
This makes many divers foot heavy. In being foot heavy the diver’s angle to the water is always in a “head pointing up” manner. This can also be referred to as “air head” but foot heavy sounds nicer. This angle can be slight, or I have seen in many cases quite severe. Every time a diver kicks, part of that force is propelling the diver up and part forward. Part up, part forward. A very inefficient kick. To keep from going up with each kick, a diver must add weight. Where does that weight go? Around the waist making the diver even more foot heavy, compounding the problem. Inefficiency usually means breathing more. More air in and out of the lungs makes a diver float more, compounding the problem. If you float you add more lead and on and on, we go…
Not one BCD on the market is correct
Not one BCD on the market is correct. I don’t need 20, 30 or 40 pounds of buoyancy control. A diver should not need more than a few pounds of control. Because manufacturers always like to make things enough for everyone, I would say 8 pounds of control is an awful lot but let’s use that for the sake of discussion. Any more than 8 pounds of lift and I highly suggest taking that much lead off and emptying the BCD. Why would I want 8 pounds of air in my BCD and add 8 pounds of lead to equal the air when I can get rid of the air and the lead?
Where should this 8 pounds of buoyancy control be? Definitely not at the neck. This lifts a person up at the head creating a very bad swimming angle. This is what every single BCD on the market does. Not at the feet which is impractical and lifts the feet up. The only place is in the middle which balances the diver. This cannot be in front (on the stomach) as it would flip the diver over. Years ago, one manufacturer had a horse collar BCD with both bottom and top flotation. The idea was there but done all wrong. The place for an 8-pound bladder would be at the bottom of the BCD and at the back.
There are some arguments against this. Yes, it would need a separate inflator – one that is very restricted so it would inflate very slowly. The actual partitioning of an existing BCD should not be too hard as all that has to be done is ultrasonically seal it. A simple manual dump valve could be installed since it is an easy place to reach. Another argument was that it would require another inflator, more hoses etc. This can be worked out as either a separate hose or incorporating the current one to do two jobs. Many got upset when the auto inflator first arrived. “All of them there extra hoses!!” Hoses became accepted but it took how many years to finally get rid of CO 2 cartridges and thank you for getting rid of them.
BCD’s have come a long way since horse collars, which still have a use in certain places. But BCD’s have been mostly marketed and not designed to a diver’s needs. The current rash of BCD’s designed especially for women also leave a bit to be desired. Only a few are really designed for women. The rest, well, just marketed as such.
Too many divers are sold a BCD that is much too large
I am sure I would be sold a large and if I told the store salesperson, I was wearing a 6mm wetsuit, I would be forced to try even an extra-large. A salesman was in my store recently with a sample of a “woman’s” BCD. It fit me well and it was supposed to be a woman’s small! I am sure if I had been in someone else’s shop, I would not be allowed to buy something that small even though it was a great fit. “You need bigger especially if you are wearing a wetsuit.” When I think of how much “bigger” a wetsuit makes me, it just isn’t much. I certainly don’t look like the Michelin man when I wear it so why do I need a BCD 2 sizes larger than what fits me? I guess I just need all that lift! Ah, the BCD wars.
Bruce Bowker