SMB / Safety sausage deployment at depth

[geoff w]

Last weekend I was talking to diving relatives about current and deploying safety sausages if someone gets caught in current during a dive (several of us are going to Fiji in June). In theory it sounds simple enough - squirt air in to safety sausage, let line out of attached reel, slowly ascend doing safety stop. However, in an open water column, when you start inflating the safety sausage, doesn't it change your buoyancy? Is the trick to release air from your BC to fill the safety sausage (no net change in buoyancy), then as you release the SMB to the surface, add air back in to your BC to regain neutral buoyancy? Or is there some other way to do this in practice? Am I missing something or trying to overthink the process? Up until we talked about this, I always assumed inflating the safety sausage was the same whether on the surface or underwater, but now I'm not sure

 

[Deefstes]

No you're not missing something, it's a good question. There are specific techniques for deploying an SMB and I studied some video clips when I wanted to get clarity on this topic. I can't remember where those clips are now but I'm sure you'll find some if you just search around on Youtube a little.

Here is what I do, and bear in mind, the DIR guys will probably identify any number of errors in this approach, but it works for me:

1. Get the SMB out of my BC pocket and unroll it. I have a 30m spool attached to the SMB.
2. Hold the spool between my thumb and middle finger of my left hand and blow the slightest amount of air into the SMB just so that it stands upright. This makes it easier when I'm ready to put the final amount of air into it and letting it run.
3. Hold the SMB with the index finger of my left hand, ready to let it go by just straightening the finger.
4. Look up to see if the path to the surface is clear.
5. Critical step: Inflate the SMB. I used to use my octo for this but are fairly comfortable with the procedure now so I just use my primary. If I'm on a solid surface I deflate my BC entirely but if I'm in open water I deflate my BC slightly. I then breath out just as I start inflating the SMB. I give it a proper blow of air for 2 or 3 seconds and then let it run.

I guess the important thing is to inflate the SMB as quickly as you can and not holding on to it any longer than is necessary. Inflating it takes only a couple of seconds so it shouldn't have much time to pull you up anyway. Seeing as I've deflated my BC just before inflating the SMB I'm slightly negative after releasing the SMB. I can compensate for this by just putting more friction on the spool with my hand until I've added air to my BC again.

All this deflating the BC stuff is a bit theoretical though because on most dives I try to weight myself such that I need very little air in my BC anyway. But even then, by inflating the SMB quickly and letting go of it as soon as I can, I usually don't get pulled up by it.

If I am negative after releasing the SMB I often don't even bother to get neutral again because I can just hang on to the SMB. This is probably not good practice but it's convenient. I rarely deploy the SMB if I'm not about to ascend (or have started my ascent already) so neutral buoyancy isn't all that important to me then. In fact, I often sit out my safety stop by clipping the spool to my BC D-ring and just hanging off the SMB.

Like I said, this is how I do it. I'm not a hugely experienced diver so please don't put too much value on this advice. I just thought I'd put it out there and you can take from it what you think is safe and can the rest.

 

[Searcaigh]

I usually use my octopus for inflating the SMB, however always remember to let it go immediately otherwise you might start an uncontrolled ascent. Make sure your line is already attached before inflating.

A few months ago a new buddy of mine inflated her SMB and nearly shot to the surface from 6M, I managed to grab her ankle and dump my air whilst still holding on to my camera housing and prevent a possible incident.

Practice with the SMB on every dive until you are totally comfortable with the deployment and it becomes as easy as breathing from your regulator.

 

[DevonDiver]

If you have a small DSMB, then orally inflating it from depth won't change your buoyancy (until you inhale again). It's quite possible to practice and get slick with deploying the DSMB with a single breath and immediately deploy it, before replacing your regulator and inhaling again.

If you are using an air-source (primary, secondary or nozzle) to inflate a larger bag, then you will gain buoyancy until the point you release it. The solution is to become slightly negative - use your breath control and, if necessary, fin to maintain constant depth - reducing your lung volume and finning power as you add air to the DSMB to compensate for the increasing buoyancy. Once released, you get neutrally buoyant again...and continue your ascent by reeling up..

 

[Saudi-Diver]

Next to people running out of air in my experience the next most common incidents seem to be associated with poor DSMB deployment. I have seen a number of near misses. The answer seems to be practice, practice and more practice. Its a skill to be honest I was never trained in I just picked it up as my diving career progressed, here in Scotland if your diving from a boat you will deploy a DSMB. I use a Reel and tend to deploy when I start my ascent. For tropical diving I would use a finger reel and deploy from my safety stop. My procedure is

1. Unravel DSMB, unclip reel

2. Attach DSMB to Reel using bolt snap

3. Using Octo put a wee bit of air in to DSMB to straighten out buoy and tension line. The amount of air I put in the buoy at this stage is easily controllable with my lung volumn.

4. Visually inspect buoy/ reel and check above for obstructions/ other divers.

5. Using Octo add more air and release buoy. In the event of the line jamming you can just let go of the reel.

This procedure works for me.

I think DSMB deployment should be covered in open water training.

 

[Spazzy]

Go get some training

 

[Deefstes]

Go get some training

WHAT?!?!? You can't be serious?

 

[DevonDiver]

I think he is serious... and justifiably so. DSMB deployments account for far too many DCI incidents (according to BSAC reports). Deployment is a relatively complicated skill - so it is definitely a good idea to get some input and supervision when learning and practicing. Where that input/supervision is with an informal mentor or formally on a course, depends on your network and resources...

If more people got trained...then I am sure the DCI statistics related to DSMB use would decrease.

 

[Deefstes]

OK, just don't let PADI find out about this as it sounds like the perfect subject for yet another speciality course, through which they can relieve yet more divers of yet more money.

But if "training" also refers to a friend showing you the ropes then I'm all for it.

 

[Wookie]

Snip....
But if "training" also refers to a friend showing you the ropes then I'm all for it.

However anyone chooses to "acquire" the training, SMB deployment training and practice is a valuable skill for anyone diving from a boat, especially in a current. I highly recommend it. Shooting a bag while laying in a pool will be as valuable as shooting one in open water. It's that first couple of feet that get you, not the other 60.