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Vintage Scuba: Evolution of BCs

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This is the next step in the evolution of the BC – did I say BC? Buoyancy compensator. This is actually one of the very first true buoyancy compensators – it’s tough to call a horse-collar or (Mae West) vest a BC. What’s the difference? It’s still got a CO2 cartridge – still got the straps and an overpressure valve – but else does it got? Aha! Look here! The tube has changed. Does it look familiar? This is like the corrugated hose that’s on your BC.

By Alec Peirce

Now look what you can do underwater: reg out, reg back. I can put some air into this vest so if I’m deep and too negative, I can make myself more positive. As I’m coming back to the surface and the vest starts to expand, I can push the end and the air comes out. This is a true buoyancy compensator: you can put the air into it under water and let the air out as you’re ascending. You can compensate, adjust, your buoyancy. It’s one of the first BCs and all because of that device. That’s all there is to it.

Let’s see how it developed from there. Lots of companies got on the bandwagon then and they all started making BCs. Here’s typical one made by a company that’s still here today, Sherwood. This is from the ‘70s: same kind of thing: pocket on the front and it still has the CO2 cartridge since they didn’t disappear until the ‘80s. This is a horse-collar buoyancy compensator – “Mae West” had probably been gone by then.

The Sherwood model has a couple of additional features. First of all, you can blow air into just as you do today and let air out. It also has a dump over here so it doesn’t get over pressurized and blown up on ascent – which you can manually dump, too, just as you have on your current buoyancy compensator. Look at your own BC and you’ll see you have at least one of these, if not two.



What else has it got? Look down here. What’s this? Someone has gone and added an after market addition: a power inflator, just like the ones you use today. Someone came along and said, “Hey. This is a nuisance having to blow this up underwater.” They sat down and figured out a way to hook this BC hose to the tank. A lot of divers today would say, “Well, I don’t want to put one of those power inflators on because they use up air from the tank, and if they use up the air I can’t stay down as long.” (Some of us old divers said those things; I said them too.) I learned quickly that, in fact, careful use of the power inflator saves air. If you use it just when you need it, at the bottom of your dive at 60 feet, letting a bit of air in is better than kicking like mad to hold yourself in position. Which uses more air? On the way up, get to where you want to stop, and again, it saves you from having to kick with your hands and arms.

It took a while before we caught onto the fact that a power inflator valve (PIV) actually saved air, and after that, it became common. All BCs today have the same power inflator valve. The horse-collar style disappeared, and we took this BC and made it into a jacket, attaching a tank to it.

-Alec

Join Alec in the final installment of the Evolution of BCs Vintage Scuba series in our next edition of Scuba H2O Adventures Magazine.