Self-inflating SMBs

[The Chairman]

I haven't tried to deploy a sausage on a CCR. I do see that in my future.

 

[hroark2112]

Hroark

Not a nice a nice solution on a CCR, especially in a drysuit.

As I say, I can do a normal DSMB if needed but it a faf, so the little gas cartridge version makes like very straight forward.

Gareth

Worked great from 180' on the Lowrance a few weeks ago. I can't claim it as an original idea though. Got it from Lamar Hires during training with him last month.

 

[DevonDiver]

How hard is it to blow into a SMB?

BSAC accident reports illustrated that DSMB deployment was a factor in a significant number of diving injuries. PADI even released a standardized 'DSMB' distinctive for the UK to address some of these issues (at the time, it was looking like DSMBs would become mandatory equipment for the UK).

Whilst inflating a DSMB isn't rocket-science, doing so whilst minimizing the risk of diver entanglement in the line, or issues with jammed reels etc, can be more problematic. These problems can lead to rapid, uncontrolled, ascents.

I've seen (and, on occasion, had to intervene to assist with) novice-intermediate divers getting tangled in DSMB lines. I don't think it's an uncommon problem.

I see lots of 'bad technique' with DSMB deployments - most of which stems from allowing slack line between the DSMB and reel... and/or not keeping the reel at arms length during deployment.

15 years ago, I owned a CO2 cartridge self-inflating DSMB. It seemed an easy and quick solution for DSMB deployment. All you had to do was unroll the DSMB, pull a cord and 'whoosh' the DSMB was on it's way to the surface.

However, over time, I just couldn't shake the unease of thinking that the mechanism could malfunction and/or be accidentally triggered during the dive... when the DSMB was clipped off behind me. That never happened, but in the end, I sold it on eBay. I've used oral/LPI-inflate closed or semi-closed DSMBs ever since. I took the time to refine my skills for deploying them safely and now it's a quick and easy process.

I've had reels jam during DSMB deployments several times. On the worst occasion, with a lot less experience, I was dragged up more than 10m before I let go of the reel (a matter of 2-3 seconds). For that reason, I much prefer using finger spools. Even if you let them go, they unwind and come back down to you. Obviously, there are depth limitations with finger spools... and if you need to deploy from depth at the beginning of an ascent (strong currents etc), then a reel is your only option. If a reel is prone to tangling/snagging, then it shouldn't be used for DSMB deployment. Some reels are definitely better than others in this respect.... the biggest issue often being the 'clearance' between the reel itself and the handle or body.. and whether the reel design permits the line to wrap through this gap.

For tech courses, my goal is for students to deploy a DSMB within 1 minute, without interrupting the ascent schedule. Shooting an oral-inflate DSMB from a large finger spool seems to be the quickest, most fool-proof and least task-loaded method...in my experience and from what I observe with students over the last decade.

I don't know about other training agencies, but on my JJ-CCR course with IART, one of the skills was DSMB deployment. I can see the value of a self-inflating DSMBs when diving a loop makes oral inflation 'problematic'. That said, there are plenty of alternate strategies, depending on your CCR unit and equipment set-up.

 

[Edward3c]

BSAC have had DSMB deployment in core training for number of years.

Sports Diver: Deploy from the bottom @ 10m, with a simulated deco stop at 6.
Diver Leaders: Deploy mid-water 10m whilst maintaining depth within +/- 0.5m, having made a no-reference ascent from the bottom (at least 15m), then do a deco stop @ 6m.

It's also an activity I get Dive Leaders and Advanced Divers to do for the Buoyancy Workshop if they look like borderline Gold/Black standard. Those who use one on a regular basis usually get the Black Standard (+/- O.3m).

 

[Gareth J]

I will try to summarise.


Deploying a DSMB appears to be a simple and straight forward skill.


However – Incident reports show that it is a cause of a large number of uncontrolled ascents, as such there are a number of precautions.

1. NEVER, EVER, have the reel attached to the diver during or after deploying a DSMB.
2. Keep the amount of ‘free’ line in the water to an absolute minimum.
3. Be prepared to jettison the reel and DSMB in the event of the line jamming.
   
4. A diver should be able to deploy a DSMB without assistance.
   
5. If using a DSMB that relies on a gas cartridge, be that CO2 or refillable cylinder. It should be possible to fill the DSMB the traditional way, and the diver SHOULD BE CAPABLE OF DOING SO.
   
6. Practice makes perfect!

Incident reports often site the following when discussing accidents relating to DSMB's


The end result is normally a diver having being dragged to the surface. Either due to entanglement, or reels jamming.

The risk of entanglement is not just from the line, but Regulators, BCD inflators, etc, getting caught in the DSMB during filling. The other entanglement issue is other pieces of diver equipment, such as torches, stage cylinders etc getting caught in the DSMB or the line.

Also, be aware that there are often obstructions or risks form things above you, be they parts of the wreck or dive site. Or surface boat traffic snagging the line. DO NOT CLIP THE REEL/SPOOL TO YOU, be ready to let go if there is a risk of being dragged to the surface.


Gareth

 

[tr3a]

Inflation concept reminds me of the old Fenzy's and Nemrod BC's

 

[dumpsterDiver]

I know very little about rebreathers but why is inflation of a SMB a problem? Dontcha guys have bailout bottles/regulators that you can use to inflate a marker without getting off the rebreather?

 

[Jim Lapenta]

I use and sell DSMB's in 36 inch, 4.5 ft, and 6 ft lengths. Normally for local diving I only carry the 36 since most of our quarries are small and no waves to overcome with a large tube. Great Lakes, river, and ocean diving I take the 36 and a 6 ft.

Teaching DSMB deployment in the pool with a 6 ft is a pain in the butt and can be intimidating and frustrating for students. The 36 inch is the perfect tool for me to use with my students. I have had 8 yr old kids deploy the 36 on breath-hold dives with a spool.

At 10 ft a 1/4 breath will have it fully inflated on the surface. With less than 10 lbs of lift the risk of rapid ascent due to getting caught up in the line is greatly minimized. As such we can deploy multiple times and just pull it back down to practice. In the quarry the 36 is big enough to provide an ascent line giving the students a visual and tactile reference. However the lack of significant lift means they also have to manage their buoyancy and not hang on the tube.

Once on the surface they can deploy the larger 4.5 or 6 ft sausage if it's required.

As for spool or reel some factors we encounter are the conditions that may require heavy gloves. Spools can be used with practice but the more popular choice seems to be a small reel like the Manta Nano or Nano plus. Well made, tough to tangle (though like any reel not paying attention will allow you to make a nest out of it), and has 50 -75 ft of line depending on the the line weight. The larger one is in the 125 - 150 range. My spools and reels tend to be set up with the lower values as I like to use #36 vs #24. I also use these as lines for wreck dives and so prefer the heavier line. I've sold a few of them and will package them with a DSMB.

 

[rongoodman]

I know very little about rebreathers but why is inflation of a SMB a problem? Dontcha guys have bailout bottles/regulators that you can use to inflate a marker without getting off the rebreather?

I just keep a BC hose on my bailout bottle and use that to inflate the SMB with.

 

[gcarter]

I have three DSMBs of various sizes.

Pet peeve: size (length) is always indicated, lift capability is (most often) not. The lift capability needs to be considered in conjunction with length, as it has a direct bearing on deployment effort depending on depth and can influence the appropriateness of selection to a particular type of diving.