(D)SMB or Safety Sausage for safety in current

[boogs34]

I am a vacation diver with 110 dives under my belt. Always trying to learn. I just came back from an amazing trip in the Maldives where we did a lot of hook diving and some incredibly strong currents (was told by the more experienced divers that the currents were unusually strong and "like Komodo"). Of course every day is different but the diving in the Maldives was surprisingly challenging (I had picked the Maldives because I was bringing my recently certified girlfriend). Anyway was a very good learning experience but I struggled with one thing.


Anyway, the SMB provided were the same open ended types that dive guides typically employ (research calls this a DSMB?). I was sent up early a few times as my buddy ran low on air. This led to the realization that I am not good at deploying DSMBs. It would not stay afloat when I deployed at depth - a skill I am lacking. (I typically dive with a safety sausage I own that you manually blow into and it stays closed). It was important to deploy at depth due to boat traffic on some sites.


But I am trying to improve and am wondering for those future bucket list trips to Cocos / etc. what should I be using? I read on another thread here an sausage + reel should be totally fine for "when you need it". That is you can manually inflate the sausage under water with 4 breaths, and send it up with the reel. Can someone confirm this is practical? Or should I be investing in a DSMB and practicing with it? Any recommendations or thoughts from more experienced divers?


Is the "trick" to the DSMB keeping some tension in the line so it stays afloat instead of just falling down? That could have been my problem as I did not have a reel...and I did not have that problem when the divemaster gave me her reel on another dive when I was taking up the less experienced divers of the group.


Either way, I plan on practicing on my next trip whichever I decide based on some advice I read here.

 

[J-Vo]

Not all DSMBs are open bottom. A DSMB is essentially a sausage with an over pressure valve.

Get one of those, a spool, and practice practice practice.

 

[shoredivr]

Here’s a video on how to shoot a DSMB, and reasons why to use this method.

 

[shoredivr]

One thing missing from the video is looking up before you inflate the DSMB to avoid hitting anything with it, or getting the line entangled.

The deeper you are in the water column when you inflate the DSMB, the less gas you need, as the gas expands as the pressure decreases. So at 70 ft maybe only one breath depending on the size of the DSMB, at 30ft maybe three. Inflating at the surface maybe four breaths, and so on.

However inflating deeper in the water column means you have more line to manage. In courses I’ve taken, keeping the line taught is important. You might even pull down on the line to get the DSMB to be upright. You don’t want to get entangled, as the video stresses.

You also want to be comfortable with your buoyancy control, so you’re not drifting up or down in the water while launching. Practice everything slowly and deliberately. Keep your breathing rate slow, so you’re not over inflating your lungs and slowly drifting shallower. “Slow is smooth, smooth is fast.”

As you ascend, you wind up the line. I was taught when I first got my spool and line to tie knots in the line, one knot at 10 ft, two knots at 20 ft, three knots at 30 ft and so on so I have a rough idea of my depth.

Maybe practice in 15 ft of water for a while, and once you get the hang of launching and line control, try deploying it in 30 ft and notice the difference in how much air you need to blow in for the DSMB to be full when it surfaces.

For some deep (decompression) diving applications I’ve deployed a DSMB from the bottom at 150ft, when I want the boat captain to know my location right away. But for the kind of Rec diving you’re doing now, between 30 and 15 ft should give adequate marking of your position.

 

[shoredivr]

One other thing is that in a current, the flow of the water can differ in both direction and speed. So at the surface the water - with your DSMB - is moving along faster than you are at depth. Or maybe going in a different direction. Which is why launching 30 ft or 15 ft of depth might work for you, less to manage.

 

[BlueTrin]

Here’s a video on how to shoot a DSMB, and reasons why to use this method.

That’s a nice vid but it wouldn’t work with a DSMB that is very large and that you need to inflate with your octo, isn’t it ?

 

[shoredivr]

That’s a nice vid but it wouldn’t work with a DSMB that is very large and that you need to inflate with your octo, isn’t it ?

Sure. Open bottom, large DSMBs can be filled with an octo. Just don’t tangle the line with the octo.

Another option is to have an extra LP hose on your stage or deco bottle which can be used on certain styles of non-stick DSMB inflator valves, where the LP collar mechanism does not attach to the inflator valve. The DSMB just pops off the LP hose when you let go.

There are several ways to deploy DSMBs. The OP can start practicing somewhere.

 

[boogs34]

Thank you. I think I know what I was doing wrong. But I absolutely need to practice. My buddy was a natural at it and did it perfectly every time. But she's also a natural at almost everything dive related...

There is 0 chance I would have been able to do what she did at my first few dozen dives.

Anyway the message is clear: get my own dsmb and practice using it AT DEPTH. I won't have to worry about learning to use some other dsmb if I am comfortable with my own (and size matters). Leaning towards the DAN dsmb + reel based off my research on older threads here.

 

[scubafied]

To add to what @shoredivr said in regards to current.....DSMB's can have a tendency to act like sails because of differences in current speed. Make sure you've discussed the plan with your buddy so they can send their's up at the same time or at least be near by when you shoot yours in the event you start to pick up speed. I've seen groups get pretty scattered and blown apart in heavier current during this stage of the dive.

 

[Akimbo]

It isn't mandatory to deploy the DSMB from near the bottom. I deploy mine for most dives from my first stop. When my first stop is less than 20'/6M I prefer this setup:

See: Reels of death?

The downside of deploying the bag when so shallow is you have to give it a pretty good blast of gas from your second stage to come close to having it fully inflated at the surface. Even then, the buoy will not be upright unless you are seriously overweighted, regardless of how it is deployed. It still helps with boat traffic, especially if they know it is an area with a lot of divers.

Deploying shallow helps when surface currents are much higher than at the bottom. Another advantage of deploying from your decompression or safety stop is you aren't spending time deploying that adds to your decompression obligation. Reels definitely have their place, but are more trouble than they are worth to me on typical recreational dive profiles.

Having the webbing hanging below you significantly reduces the risk of getting entangled in a buoy rocketing for the surface, or the spool ripped out of your hands if the line binds up.