divetrippers
07-01-2008, 09:07 PM
Some info from one of PADI's Instructors nice enough to pass along:
Recreational BCD options
Recreational BCDs have come a long way in the comfort department. Most are extremely adjustable and have a bunch of lift (buoyancy capability) and most are similar in design and function. There are, however, several variations to consider when purchasing your recreational BCD.
A quick history
When Scuba was first introduced, divers didn’t wear BCDs. They fine-tuned their weights so that they could use their lungs as miniature buoyancy devices. Then along came horse collar BCDs, developed by Michael Fenzy in 1961, which were orally inflated at the time but they made it easier to be less careful about being perfectly weighted. Ten years later Scubapro developed the first jacket style BCD. As the years have passed, the evolution of the BCD has brought about different options including back-inflation, weight integration, and pneumatic inflators.
Back Inflation
Back inflation BCDs are popular for shore divers because of the long surface swims sometimes necessary to get to the descent spot. Kicking on one’s back with a back inflated BCD is nice because it’s like lying back on an air mattress on top of a water mattress. Also, while kicking on one's back, the diver’s head is nice and high out of the water so there is less drag while kicking and less water on the face than wearing a back inflation BCD.
On the surface, though, when the kicking’s done and it’s time to descend, the back inflation BCD will have a tendency to push your head down. That’s why most of the back inflation BCDs will have non-releasable pockets in the back for small weights to balance you out on the surface.
Another advantage of a back inflation BCD is there is no squeeze on your belly when the BCD is fully inflated so there is an ability to get more lift out of a back inflation BCD.
Many recreational divers like the feel of the traditional wrap around BCD underwater because the air wraps around the BCD nicely making it easier to maneuver for some people. Wrap around BCDs are thought of as being more comfortable on the surface for extended periods. Also, many rental departments and classes use the traditional jacket style BCDs so it is the style many divers are familiar with.
Weight Integration
Weight integration is a great tool for recreational divers. Integrating the weight system makes for a comfortable system, especially when a lot of weight is needed or when the diver's waist is larger than his/her hips. The stress of the heavy weights with a weight integration system will be on the shoulders and mid back and that's a nice thing when you've got to do some walking with the tank on your back to the site's entry point. For those with a larger waist, a standard weight belt is difficult to deal with because it's constantly slipping down over the hips.
In the water, especially on the surface, weight integrated BCDs help with the problem of a weight belt pulling you down, and the BCD pulling you up separately. Integrated, it seems to be a more natural feel.
Pneumatic Inflator
Some manufacturers these days are offering a pneumatic inflator which rests on the bottom left pocket of the BCD. The advantage of this system is there is not a dangling hose coming off the BCD and you can vent out air from the BCD at any position. With standard inflators, you must make sure your are in an upright position for the air to vent out of the highest point. Although most BCDs will have dump valves elsewhere so you don't have to go upright to vent out air. The nice thing about the pneumatic system is you'll always use your left hand at the same spot to dump some unnecessary air.
Most certification agencies these days recognize the pneumatic inflator as being an acceptable piece of scuba equipment for training and recreational diving.
Recreational BCD options
Recreational BCDs have come a long way in the comfort department. Most are extremely adjustable and have a bunch of lift (buoyancy capability) and most are similar in design and function. There are, however, several variations to consider when purchasing your recreational BCD.
A quick history
When Scuba was first introduced, divers didn’t wear BCDs. They fine-tuned their weights so that they could use their lungs as miniature buoyancy devices. Then along came horse collar BCDs, developed by Michael Fenzy in 1961, which were orally inflated at the time but they made it easier to be less careful about being perfectly weighted. Ten years later Scubapro developed the first jacket style BCD. As the years have passed, the evolution of the BCD has brought about different options including back-inflation, weight integration, and pneumatic inflators.
Back Inflation
Back inflation BCDs are popular for shore divers because of the long surface swims sometimes necessary to get to the descent spot. Kicking on one’s back with a back inflated BCD is nice because it’s like lying back on an air mattress on top of a water mattress. Also, while kicking on one's back, the diver’s head is nice and high out of the water so there is less drag while kicking and less water on the face than wearing a back inflation BCD.
On the surface, though, when the kicking’s done and it’s time to descend, the back inflation BCD will have a tendency to push your head down. That’s why most of the back inflation BCDs will have non-releasable pockets in the back for small weights to balance you out on the surface.
Another advantage of a back inflation BCD is there is no squeeze on your belly when the BCD is fully inflated so there is an ability to get more lift out of a back inflation BCD.
Many recreational divers like the feel of the traditional wrap around BCD underwater because the air wraps around the BCD nicely making it easier to maneuver for some people. Wrap around BCDs are thought of as being more comfortable on the surface for extended periods. Also, many rental departments and classes use the traditional jacket style BCDs so it is the style many divers are familiar with.
Weight Integration
Weight integration is a great tool for recreational divers. Integrating the weight system makes for a comfortable system, especially when a lot of weight is needed or when the diver's waist is larger than his/her hips. The stress of the heavy weights with a weight integration system will be on the shoulders and mid back and that's a nice thing when you've got to do some walking with the tank on your back to the site's entry point. For those with a larger waist, a standard weight belt is difficult to deal with because it's constantly slipping down over the hips.
In the water, especially on the surface, weight integrated BCDs help with the problem of a weight belt pulling you down, and the BCD pulling you up separately. Integrated, it seems to be a more natural feel.
Pneumatic Inflator
Some manufacturers these days are offering a pneumatic inflator which rests on the bottom left pocket of the BCD. The advantage of this system is there is not a dangling hose coming off the BCD and you can vent out air from the BCD at any position. With standard inflators, you must make sure your are in an upright position for the air to vent out of the highest point. Although most BCDs will have dump valves elsewhere so you don't have to go upright to vent out air. The nice thing about the pneumatic system is you'll always use your left hand at the same spot to dump some unnecessary air.
Most certification agencies these days recognize the pneumatic inflator as being an acceptable piece of scuba equipment for training and recreational diving.