Let's discuss this for a moment -- IF he can get a "few feet underwater" with the "Bob Technique", then how would he now become MORE buoyant? There are only three ways I can think of: a. He puts air into his wing; b. He puts air into his dry suit; or c. He takes a deep breath now that he is "a few feet underwater." Of course, if he is still vertical, he has probably now gone back to "happy feet" while he takes that big sigh of relief, both of which will stall him out as he has described.I can only seem to get a few feet underwater and kinda stall.
OP -- I know you specifically did NOT ask for advice, but you are going to get some, the same advice one of the world's top horse trainers gave to students -- Do More Of Nothing. In other words continue to just let yourself sink -- don't kick, don't breathe too much, DO exhale completely, don't move your hands -- Do More Of Nothing.