If you have a few minutes, I have an interesting story for you.

I have been slowly gaining weight since over the last 9 years. So last summer, I finally decided to do something about it. I posted a piece of graph paper on the fridge and started tracking my weight. I ate smaller meals and cut back on the fatty foods. In addition, I started exercising for longer periods. It worked. It was gratifying to see the pounds drop away and once I got rolling it wasn’t difficult. In all, I lost over 20 pounds of blubber. It didn’t come without a price however.

I had to buy a new belt and pants because those old ones were way too big for the new and improved me. However, I looked at the cost of those new pants (and belts) as the price I had to pay for my new streamlined look. So, on a subsequent dive, it came as a no surprise that my BC was too big and was shifting around during the dive.

I will admit, I had had my eye on a new BC even before I lost the weight, but now I had the excuse I needed to fork over some serious dough for the latest and greatest. The BC I was drooling over was one of those new rear inflation models with a dozen stainless D-rings and integrated weight pouches. It looked incredibly manly just hanging there on the rack. Not only did this work of art look good, but also it felt great. I tried it on, it was comfortable and solid. I could tell it wouldn’t be wandering around on my slim body like the old BC. I bought it.

Much to my surprise, I had some problems on the first dive with my new BC. My attitude was off. I was swimming through the water tilted. I was leaning over on the left side and my right side was up. I wasn’t sure why, but it was annoying. I rocked left and right to see if it was a lodged air bubble but that didn’t change anything. Towards the end of the dive, I popped up to the surface to get a bearing to the shore. After I went down, the tilt disappeared. The last few minutes of the dive were enjoyable and without any weirdness. The only explanation I could think of was that there must have been an air bubble on the right side of my BC that shifted to somewhere harmless or disappeared after my ascent to the surface. Intrigued, I decided to do a little testing in the local swimming pool.

I took my "New and Improved" BC to the swimming pool the next week. At the pool I confirmed my fears. My new expensive BC looked good, but didn’t work very well. Here is the scoop....

I found a couple of problems at the pool. The first problem was that air bubbles and big rear inflation bladders don’t mix well. Air inside of a BC, displaces water at the highest point of the bladder. Inside my new BC air bubbles tended to float to one side of the huge bladder and lift it sufficiently to prevent it’s release while swimming in a normal position. As long as I was swimming level I could rock left or right all I want and it wasn’t enough to shift the bubble. The bigger the bubble, the bigger the problem.

Because the average divers buoyancy changes about 4 - 5 pounds due to air consumption during a dive, it is not unusual to have at least some bubble at the beginning of the dive. That way, you can trickle it out during the dive and still be near neutral at the end of the dive. If you are under weighted, you may well float to the surface (perhaps at a bad time) towards the end of your dive as you drop weight from air loss.

Problem two: In a rear inflation BC the bladders tend to be very big. Big bladders can also be a problem because any air in them tends to be much further from you body than a vest style BC. This increase in distance amounts to a greater torque on the diver for a given bubble size over a vest style BC. Vest style BCs hold air closer to the body and distribute bubbles over a greater area. This results in less susceptibility to weighting issues over the big bladder style BC’s. Since most divers need a 4 - 5 pound air bubble at the beginning of the dive (to compensate for air loss) I could not see a rear inflation style working very well for me.

Problem three: In addition, when I was at the surface with my rear inflation BC nearly fully inflated, it was difficult to get a breath of air because my face tended to be in the water. Why would I want my face to be in the water while on the surface? Although I could flip over on my back, that took a lot of energy and the process felt unnatural.

I’ve been diving too long to put up poorly designed equipment. You need more than good looks and popularity to impress me. I need functionality. So, with great sadness, I hung up my expensive manly rear inflation BC and resumed my search for a better BC.

Then came a humbling revelation, in dusting off my oldest BC in preparation to sell it, I noticed the real reason the BC had been moving around during the dive. Both sides of my cummerbund had slid out of the looped mounting straps located on the inside at the BC (both left and right). Apparently, when the cummerbund had been re-threaded, I had carelessly passed the cummerbund behind the straps rather that through the narrowly sandwiched and stitched straps. This resulted in the sides and the front of the BC moving around like crazy during the dive!! It wasn’t the weight loss after all. The problem could be traced back to the bonehead who created it, ME! So I properly threaded the cummerbund and retested the BC. Sure enough, my original BC fits well and works like a champion.

A few thoughts…. The old gear sometimes works better than the new.  Be alert when changing or adjusting your gear. You don’t have to spend $500 to get a great performing BC. Magazine performance reviews don’t tell it all. Read carefully, do some research,but most of all .... think for yourself  

Stay tuned for additional stories.

John Burns, Owner, Discount Divers Supply

John dives with a ProSub Mariner BC, modified with a Sea Tec tank strap.