Quick poll—When do you inflate your SMB?

[Wookie]

I must try that, I have a crack bottle dsmb which goes off like a missile

And I've written the speciality on winding spools badly.

My crack bottle DSMB is always the last one to be used, as I’ve lost the orange one and the green one by then. I’ve never had to use it yet.

 

[RyanT]

Pro tip - power inflate from you LP inflator hose. Its the shizzle. The dump valve keeps it from over pressurising, woooosh, and up it goes.

I have an extra LP hose with a blow gun nozzle attached. It's so easy to stick it in the bottom of the bag, inflate, and away it goes. Also, it means no unconnecting my inflator hose from my wing to inflate the bag.

 

[seeker242]

OK, let me rephrase that... hands up if you haven't had an embarrassing DSMB moment!

I would like to thank the guy who invented neutrally buoyant spools.

 

[NothingClever]

During an OW deco dive, after I’ve switched from bottom gas to first deco gas is when I shoot my DSMB. It provides a helpful way to get myself and the team locked in tight to our virtual ceilings.

In other circumstances, I make a plan/decision based on:

a) crew proficiency
b) dive team proficiency
c) sea state
d) surface visibility

I think the input from more experienced divers here about the amount of surplus line they like to carry is informative. I’ve thought my 30m spool for a typical 21m shot was adequate but I’m learning it’s probably not for some seas.

 

[Marie13]

I have an extra LP hose with a blow gun nozzle attached. It's so easy to stick it in the bottom of the bag, inflate, and away it goes. Also, it means no unconnecting my inflator hose from my wing to inflate the bag.

Link to nozzle, please?

 

[rongoodman]

DGX Adapter: HQ Air Nozzle = BC Inflator QD Post | Dive Gear Express®

The problem with the open bottom bags, though, is that they're worthless for extra flotation on the surface if you need it, or holding them up in the air to make yourself more visible.

 

[RyanT]

The one that @rongoodman posted is it. Just make sure you put a piece of bungee on it and attach it to your lp hose. Otherwise, a bump on the quick connect collar could result in it shooting off into the abyss.

@rongoodman, most bags these days have a baffle in the bottom. It allows for inflation from the bottom of the bag, but prevents air spill at the surface. I've rested on my mine multiple times with no air spill.

 

[RyanT]

I’ve thought my 30m spool for a typical 21m shot was adequate but I’m learning it’s probably not for some seas.

It's a good point! I've shot my 100' spool from 80' on more than one occasion, hit the end of the line and still had it drag me up a few feet. Currents have a way of doing that! I've been thinking seriously of going to a 150' spool.

 

[uncfnp]

It's a good point! I've shot my 100' spool from 80' on more than one occasion, hit the end of the line and still had it drag me up a few feet. Currents have a way of doing that! I've been thinking seriously of going to a 150' spool.

If the current is strong enough it seems it is going to lift you eventually anyway. This was one of those learn by experience moments. My reel had 220 line. I was at about 90 and it didn’t seem like too much current at depth. I shot my bag and the line started reeling off, and off, and off. It was near the end when I decided it was let it go and probably lose it, or see how far up it dragged me. I’d estimate about 10 to 15 feet before I started drifting with the bag. Back on the boat I learned this was about typical. Fortunately I never had the opportunity to retest this theory.

 

[johndiver999]

If the current is strong enough it seems it is going to lift you eventually anyway. This was one of those learn by experience moments. My reel had 220 line. I was at about 90 and it didn’t seem like too much current at depth. I shot my bag and the line started reeling off, and off, and off. It was near the end when I decided it was let it go and probably lose it, or see how far up it dragged me. I’d estimate about 10 to 15 feet before I started drifting with the bag. Back on the boat I learned this was about typical. Fortunately I never had the opportunity to retest this theory.

The presence of a current is irrelevant to needing extra line. That is based on the assumption that the current is uniform (unvarying in velocity throughout the water column).

However, what normally happens is that the surface current is faster than the bottom current (as you seem to describe). This situation will cause the tethered smb to "pull" on the diver and try to drag the diver toward the surface.

A diver can offset this problem by delaying the launch of the smb to a shallower depth, and/or having a lot more line on the smb and the other thing that works is to stay heavy and HANG on the line. The fast current will tend to drag you up, but if you have enough line and enough extra ballast, you can balance the two forces and control the ascent rate. The diver may end up being pulled horizontally through the water column by holding onto an smb that it entrained by a significantly faster current on the surface. You do not want to be neutral when you first launch the smb from depth with a strong surface current.