cadiver67:
Hi,
I am looking to purchase a BCD and want a back inflate type but am a little worried about the tendency go forward at the surface.
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Back inflate BCs do not push you forward in normal use. Normal use at the surface is floating with yoru chin out of water. If you remember that a BC is at the surface is only suppose to keep your head out of the water you will be fine.
The trouble comes when divers attempt to inflate the BC too much so they float high out of the water (some seem to want to be verticle with their navels out of the water) with their chest above the surface. When you try to ride high out of the water using a back inflate bc, naturally you have put air into almost all if not all of the bladder. The bladder in turn attempts to rise out of the water and ridesup onyour boddy and this in turn pushes you face down into the water.
In a Jacket BC the air is distributed more around you and so as the BC attempts to rise above the water you don't go face down. Jacket BC also are designed to float you with your head or at most shoulder out of the water.
I dive a jacket BC (becasue that is what I bought when I got certified), but recently rented a back inflate. I did not notice any issues of the back inflate pushing my face into the water. But then, I only put a little air in my BC, enough to establish flotation and keep my head above the water.
To put it another way, this new BC sounds like a great solution to a non-existent problem. IF you feel like your back inflate BC is pushing you over, and planting your face into the water two solutions come to mind; 1. let a little air out of the BC and 2: install a crotch strap.
Bottome line, buy the BC you like for the performance DURING the dive. A BC is not a life perserver, but a buoancy Control device. The surface swim with it is a minor part of the dive and IMHO should not be the controling factor in the purchase of a BC, the dive performance should be.