I of course carry an SMB at all times - mostly clear tropical water but sometimes with howling currents. I rarely inflate from depth and like DevonDiver, usually deploy at or near the safety stop. It's a 1.5 metre narrow sausage with a dump valve and can be inflated either orally or from the LP hose, or from the non-return valve bottom using a second stage. I can fill it satisfactorily about 1/2 full on one breath of air, but usually use my alternate.
Given that I am correctly weighted when I am guiding (plus one kilo) then deploying in shallow water (5m/15ft) does have some buoyancy issues so the technique: Either as DevonDiver says, inflating orally so air is simply transferred from one place to another, or, if I use my LP or Alternate Air source, I unroll the SMB and then in quick succession, dump air from my BCD (if necessary), exhale deeply and simultaneously inflate the SMB whilst pulling it downwards - this counteracts the effects of the increase buoyancy long enough for the SMB to be inflated before I let go - it takes a matter of seconds.
I do not consider it an emergency lifting device, at all. If the BCD fails so spectacularly that it cannot contain any air at all, which I have never seen happen, then in my environment, a diver should be able to swim to the surface unsupported - if not, they are overweighted. I have never seen a BCD rupture in this fashion - small leaks, yes, catastrophic failure, no.
If I screw up so badly I need to make a rapid buoyant emergency ascent, which has never happened to me and is highly unlikely to, I would ditch my weight belt, not waste time unrolling a sausage.
Safe diving,
C.
Given that I am correctly weighted when I am guiding (plus one kilo) then deploying in shallow water (5m/15ft) does have some buoyancy issues so the technique: Either as DevonDiver says, inflating orally so air is simply transferred from one place to another, or, if I use my LP or Alternate Air source, I unroll the SMB and then in quick succession, dump air from my BCD (if necessary), exhale deeply and simultaneously inflate the SMB whilst pulling it downwards - this counteracts the effects of the increase buoyancy long enough for the SMB to be inflated before I let go - it takes a matter of seconds.
I do not consider it an emergency lifting device, at all. If the BCD fails so spectacularly that it cannot contain any air at all, which I have never seen happen, then in my environment, a diver should be able to swim to the surface unsupported - if not, they are overweighted. I have never seen a BCD rupture in this fashion - small leaks, yes, catastrophic failure, no.
If I screw up so badly I need to make a rapid buoyant emergency ascent, which has never happened to me and is highly unlikely to, I would ditch my weight belt, not waste time unrolling a sausage.
Safe diving,
C.