Inflating dsmb without flying up with it

[Bert van den Berg]

This may not be the right forum to ask but would like to know how you can properly inflate your dsmb fully without being towed to the surface when it's only half full.

DUMB IS DSMB AFTER SPELL CHECKER GETS DONE WITH IT LOL. (Mod edit, fixed your title for you)

 

[greeniguana]

It is possible courtesy of Boyles law.

 

[wnissen]

This may not be the right forum to ask but would like to know how you can properly inflate your dsmb fully without being towed to the surface when it's only half full.

DUMB IS DSMB AFTER SPELL CHECKER GETS DONE WITH IT LOL. (Mod edit, fixed your title for you)

I would appreciate some tips as well. Do you need to carry more weight when intending to deploy one? Have only tried a couple times and the first was a total failure (thank goodness the spool fell in shallow water) and the second was, well, barely adequate. Practice, practice, I know.

 

[mmerriman]

fill it at 33 feet. then its fully inflated at the surface

 

[divezonescuba]

You take a breath, get completely neutrally buoyant, exhale into the dsmb. Don’t take another breath until you release it and it is on its way to the surface.

This should be taught in an advanced class.

If you want to put more than one breath in it, you have to invert and swim down or other wise be negative.

That is a much more advanced skill.

 

[Degenerate]

I fill mine at at 10-6m, and I nearly always unplug the hose to my drysuit and fill the SMB with that.
It's really fast and I don't need to add any more gas to my suit at that point anyways, SMB always comes up filled to the brim using this technique.

Don't do any drift dives here so never really any need to fill it from depth, if that was the case a simple deep breath would do it.

 

[Brett Hatch]

Here's a decent video of a diver demonstrating how to do it. The first 2 minutes of the video they are doing something else, so skip to 2:15 mark or so.

Notice that the diver completely prepares the DSMB before blowing it up. It is unravelled, and both the buoy and the reel are in their left hand. That leaves their right hand free to handle the reg in their mouth. So they remove the reg, blow a breath into the buoy, and replace the reg. At this point, they will still be neutrally buoyant, because the gas in the buoy was a moment ago in their lungs. They will only become buoyant if they take in a big breath, but can stay neutral by taking small breaths at the "bottom" of their lungs, ie not fully inflating their lungs.

Once they do this, the buoy is halfway filled. Notice that at this point the DSMB is not attached to their body, it is loose in their hand. They do a quick check above to make sure they buoy won't become entangled on kelp or a boat or another diver or whatever. They move the DSMB and reel away from their body which will keep themselves from being entangled. And finally release some grip on the reel to allow the buoy to shoot upward. As the buoy goes up, the gas inside will expand such that it is fully inflated when it arrives at the surface (this is why DSMBs have an overinflation valve).

At that point, they can clip the line off to the reel with the double-ender, which will allow the diver to let go of the buoy and reel -- it's not going anywhere.

Some folks prefer to fill it from a drysuit or inflator hose. I guess the upside there is that they don't have to remove their reg from their mouth. The downside is that they are not transferring gas from one low-pressure compartment (lungs) to another low-pressure compartment (buoy). Instead it's from the high-pressure compartment (tank) to the low-pressure buoy. So it causes a net increase in buoyancy, versus from the lungs causes no net change in buoyancy, and makes the whole thing more time-sensitive since you'll have to swim down until the thing is deployed, which makes it harder to deploy than it would be if they could relax.

 

[lowwall]

If you are orally inflating, the air is going from your lungs to the DSMB. Thus there is no change in your net buoyancy until you inhale.

My advice is to give the DSMB a big exhale and then hold it while you put the reg back in your mouth and purge. Now let the DSMB go. As soon as you let go, you can inhale.

If you are shallow enough or your DSMB is large enough that one breath won't do it, you need to be at least slightly head down so you can kick to maintain your depth between puffs. I guess you could be heads up and negative, but if you're careful about your weighting you may not have any air left to dump at the safety stop.

 

[lowwall]

Brett and I were posting at the same time. One note on the video. Save yourself a few steps and have the spool already rigged up to the DSMB before you splash. Keeping them separate is for divers who carry multiple spools/reels/DSMBs for whatever reason (such as running lines when wreck diving).

 

[TuckerIdaho]

Here's a decent video of a diver demonstrating how to do it. The first 2 minutes of the video they are doing something else, so skip to 2:15 mark or so.

The dude who swims past at a 45 degree angle made my head crazy.