MDW - 10/30/2017 6:29 PM
That bottom dump valve should be your primary method of dumping gas if you are in decent swimming trim. If any agency is not teaching the use of the dump valve for dumping, they are doing a disservice to their students. Really, the main time the shoulder hose is useful is only when you are "standing up" underwater (which should be rare, but unfortunately is most of the time for OW divers taught by PADI, et. al.)

Get horizontal and put air in through the top (inflator hose) and out through the bottom (like the way food and drink goes through your body)