Another SMB question, or two

[Crowley]

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.

 

[dumpsterDiver]

I 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.

True, but a SMB (with an OP valve) could be used as an alternative means to control bouyancy and allow the retention of all gear and to facilitiate a safe and slow ascent in a "non"-emergency; emergency.

 

[DevonDiver]

Why ascend with the SMB?

Pop the SMB and ascend hand-over-hand up the line.
Or ascend up the shot/boat line if one is available.

 

[soccerguy83]

That's what I have been wondering the entire thread, why would you ever want to hold onto a SMB to ascend when you can just hand over hand it up the line?

 

[GrumpyOldGuy]

That's what I have been wondering the entire thread, why would you ever want to hold onto a SMB to ascend when you can just hand over hand it up the line?

If you did not have the foresight to have an adequate length of line on the SMB......

 

[DevonDiver]

If you did not have the foresight to have an adequate length of line on the SMB......

...then you're probably not the calibre of diver that should be trying to ascend with a DSMB for your bouyancy.

 

[fjpatrum]

Thank you, everyone, for the great comments.

My question regarding lift was more for "establishing positive buoyancy at the surface" than for actually getting to the surface. I don't generally have any air in my BC down to about 40 feet or so with 10+mm neoprene and in the couple dives I've done in warm water didn't use my BC until about 60 feet. I wouldn't really need to "compensate" for any lost lift of a BC like when my horse-collar-turned-wing did catastrophically fail on my first dive with it.

I believe you should be able to swim up your gear (injury notwithstanding) but I wanted to check whether other folks used it as a consideration for size of SMB. I am looking at the 6' SMB because I don't like the idea of being invisible on the water. In my opinion, this is an issue where size really does matter.

My biggest concern is the "free ride", especially since I very rarely have any air in my BC, so I'll be practicing this quite a bit in the pool. At least to get the motions smooth, if not the buoyancy adjustments.

Thanks again, everyone. Great advice, as usual.

 

[mjatkins]

Thank you, everyone, for the great comments.

My question regarding lift was more for "establishing positive buoyancy at the surface" than for actually getting to the surface.

To this specific point, I can say that although I have never considered it when it comes to establishing my own buoyancy, I do use my SMB as an example of something that can be used to reach and offer buoyancy to a diver in the rescue course. I like the tall one for the fact that I can offer buoyancy while still keeping a bit of distance between me and the victim. The big one also offers enough lift to be valuable in this instance.

I advise all my students to have one for this purpose as well as for being visible on the surface.