deploy a delayed smb

[charles scatchard]

just been looking through the feb issue of dive. I notice they are against using exhaled air to inflate. I suppose the thinking is loss of buoyancy, I and some other members of our branch have used this method for some time without any problems in fact I find it the easy option in mid water.

[Ben Panter]

just been looking through the feb issue of dive. I notice they are against using exhaled air to inflate. I suppose the thinking is loss of buoyancy, I and some other members of our branch have used this method for some time without any problems in fact I find it the easy option in mid water.
I haven't seen the article in question, but the usual thinking behind this is that there is an entanglement risk when a reel, DSMB, DV and divers head are in close proximity, and that should such an entanglement occur there is almost certainly going to be an uncontrolled ascent. Personally I've never had a problem doing it, but I wouldn't teach it. Thinking about it, I haven't actually done it on a dive for a long time - I'd need to practise if I was going to do it again.

cheers,

Ben

[John Williams]

just been looking through the feb issue of dive. I notice they are against using exhaled air to inflate. I suppose the thinking is loss of buoyancy, I and some other members of our branch have used this method for some time without any problems in fact I find it the easy option in mid water.

Oh - the benefits of being a member!:p

For those of you who can ...this topic has received a truly thorough debate in the thread in the Instructors forum within the members section:D

http://www.bsacforum.co.uk/forums/showthread.php?t=302

For those of you who can't...

Please visit your local branch and join the BSAC ...then you'd be able to see it all!:)

Luv

John;)

[Tony F]

For those of you who can't...

Please visit your local branch and join the BSAC ...then you'd be able to see it all!:)

Shameless! :D

[John Williams]

Shameless! :D

My middle name!
:D :p :D

J;)

[charles scatchard]

I haven't seen the article in question, but the usual thinking behind this is that there is an entanglement risk when a reel, DSMB, DV and divers head are in close proximity, and that should such an entanglement occur there is almost certainly going to be an uncontrolled ascent. Personally I've never had a problem doing it, but I wouldn't teach it. Thinking about it, I haven't actually done it on a dive for a long time - I'd need to practise if I was going to do it again.

cheers,

Ben
I can understand the entanglement risk but that is a possibility with any method. My point is the artical says you should NEVER use the expired air method. Surely if it works for you as an experienced diver its ok. I have used gun .aas. and like the expired air method. A point to consider 40 metre dive ending on a wreck, inflate with aas and get a free flow not the best time for that to happen with deco stops to do. I think the trick with deploying is give yourself plenty of time and do it slowly and carefully witchever method you use.

[David Walker]

I can understand the entanglement risk but that is a possibility with any method.

Absolutely. I've heard this discussed a few times, and I don't really buy the entanglement risk one. No worse than sticking your octopus in underneath it, using your drysuit hose for the nipple-inflator type DSMBs, etc. In fact, it has advantages too - you've got both hands free to hold the bag/reel - you don't need to hold your reg too, its in your mouth. If people are letting too much line out then of course its a greater risk, but then i'd suggest their technique was at fault, not the method. And of course you're eliminating the probably more significant risk of freeflows, especially in winter.

I don't use it personally, and wouldn't teach it to inexperienced divers, but thats more because it takes a bit more thinking about (various bouyancy changes, multiple breaths, etc) rather than it being more risky.... and lots of people tend to miss the bottom of the DSMB too! :D

David

[James - Narked@50]

That's strange?

The pictures I'm looking at look like it's the alternative air source, and the write up specificaly says do not use your main reg.

Have another look and check out the tips on the right of the page.

James

[Louby Lou]

The pictures I'm looking at look like it's the alternative air source, and the write up specificaly says do not use your main reg.

I hope it was an alternative air source as the diver's primary in the photos is a closed loop ;)

[Paul Beal]

I have not read this thread yet but I am glad I have now - I had to lift a student with a full on (ice, the works), freeflow while diving today. We were only at 6 m and the situation was well controlled but it was the purge button that did it.

Today was the fourth or fifth time I personally have had to sort out a freeflow during a dSMB deployment lesson over the last 3 years or so. I have seen countless instructors have the same problem. You can tell students several times in the briefing to purge the AAS slowly, you can get them doing it gently in the dry run, you can even demo that you are doing it slowly and get them to have a go with a tethered SMB. However, once they are having a go on their own (or midwater in DL training) many students will hit the purge button hard. Whether they get a freeflow when doing this in winter is a matter of luck.

I don't ever touch the purge button on my reg at this time of the year in any other situation. When diving myself I use my exhaled bubbles and have never had an issue with entanglement. Surely risk assessment is about acknowledging and minimising risk and therefore purging an octopus in 4 C water represents a serious risk that is difficult to minimise. Why therefore do we continue to recommend that students are taught to purge their regs into a dSMB? I think this is a serious issue that needs addressing because the statistics are stacked very badly against the technique.

Over the next 3 weekends my club is running 1 DL weekend and 2 sports dive training weekends - all of which include dSMB work. These will involve around 50 students and I anticipate at least 4 freeflows caused by students purging their octopus into their SMB. I am having serious deliberations about which technique to teach. Students are allowed off into the big wide world after this lesson and I shudder to think about what would happen if they had a freeflow at 20 m (or more :eek:) while with another sports diver when they both panicked. Trying to sort out a panicking diver is hard at the best of times let alone when you can hardly see them through a stream of bubbles.

What are the risks of using the exhaust from the main reg? I fully acknowledge the main and often quoted one of the straps or line catching round the main reg, tearing it from the mouth and dragging a reg-less student to the surface. This is obviously a serious problem and one that should not be underestimated. This problem can be minimised though. The strap on the SMB can be knotted; the instructor can ensure the straps are held clear; the instructor can be ready to help is necessary; the student can be corrected if excess line is taken off the reel.

I will of course go on teaching the AAS purge method but I can always guarentee I will have to continue to sort out freeflowing regs as a result of this. Could we justify something that is a known risk if the worst did happen in a dSMB lesson?

Paul

[Ben Panter]

I have not read this thread yet but I am glad I have now - I had to lift a student with a full on (ice, the works), freeflow while diving today. We were only at 6 m and the situation was well controlled but it was the purge button that did it.

Scary stuff and no mistake.

I can't give you an official answer because I don't know it, but I wonder if it has something to do with the consequences of a mishap. In your case above, worst case scenario should be that the divers resort to a shared air ascent, shook up but theoretically having already had training to cope with such a situation. In an exhaled air DSMB launch the worst case scenario is an uncontrolled ascent, possibly including the reg being ripped out of the mouth. The only training we offer for such a situation is how to administer oxygen and call in a helicopter.

The risk assessment you'd do for such a decision is the (risk of the accident happening) x (damage caused by the accident). In this case it seems that the powers that be deemed this was higher for exhaled air. I think I agree with that, but I'm open to persuasion.

cheers,

Ben

[Ed Howarth]

The risk assessment you'd do for such a decision is the (risk of the accident happening) x (damage caused by the accident). In this case it seems that the powers that be deemed this was higher for exhaled air. I think I agree with that, but I'm open to persuasion.

cheers,

Ben

That's the way I see it and teach on the nitrox course. In the last course a couple of weeks ago me and one of my students had freeflows - on separate dives, thank goodness. Mine was first, her's was second. By the time her's happened, I was so anticipating it that sorting it out was a piece of cake. If you are practiced/ready then it is a mild inconvenience - breathe off pony/twin - shutdown - wait - turn on - swap to main. We then just carried on diving.

The chance of an uncontrolled ascent due to entanglement may be much less, but the consequences may be, at worst, fatal, and at best finish diving for the day.

Ed

[Woz]

Exhaled air is the method I use. Plus you don't need to put that much air in- just a couple of breaths is perfectly fine and not enough to be a "drag to the surface" problem. Overfilling is a big potential problem- I would rather have a floppy blob than have the oooooooooooooooooo crap moment between filling the blob and releasing the ratchet. Watch the 5th D video to watch a mid-water fire. That's how much air you need to pop in. And it's not alot.

[Steve Pearson]

Watch the 5th D video to watch a mid-water fire. That's how much air you need to pop in. And it's not alot.

Where can we see this vid

Steve

[Woz]

There you go:
http://www.divetekadventures.com/Videos/VideoShotBag.htm

If you look carefully you can see the bit where he is finning slightly downwards.

Other videos and stuff:
http://www.divetekadventures.com/links.htm

[ahar]

Oh - the benefits of being a member!:p

For those of you who can ...this topic has received a truly thorough debate in the thread in the Instructors forum within the members section:D

http://www.bsacforum.co.uk/forums/showthread.php?t=302

For those of you who can't...

Please visit your local branch and join the BSAC ...then you'd be able to see it all!:)

Luv

John;)
I think that section is only available to instructors. I have access to the members section (having added in my BSAC membership details) but not the instructors section - not surprising as I'm not an instructor!

I've had a few tries now with the kind of dSMB (filled from drysuit hose) that Woz posted a video of someone using and I must say I find it much better than exhaled gas. I've been using exhaled gas for almost as long as I've been using a dSMB and had no problems, but this one seems much less messy and has less chance on tangles as the hose doesn't go near the line.

Still not as good as a buddy crack bottle though :)

[Paul Renucci]

Im going to stick my head in the chopping block.
In the lake district we have a slight problem in that half the time we cant see too well - we know where our smb and mouth is so we tend to use this method instead of fiddling around with our hose :D.

The entaglement issue is real in lakes such as Coniston, Ullswater, Windermere where viz is low - very low (2 metres in summer, 5 in winter) which can create a challenge for your buddy and self when trying to spot where the lines are. Because of this some of us opt not to use smbs.

Speaking from experience:
Another problem we have is that other water users in yachts and the like (obviously with little experience) suddenly get the urge to go chase after the smb and attempt to pull it up with their grappling hooks and us with it - say no more :eek: For the given circumstance which one is the safer option and bearing in mind that shore cover can see where we are on most occcasions. Life can be difficult in the lakes.

[Andy Wade]

Im going to stick my head in the chopping block.
In the lake district we have a slight problem in that half the time we cant see too well - we know where our smb and mouth is so we tend to use this method instead of fiddling around with our hose :D.

The entaglement issue is real in lakes such as Coniston, Ullswater, Windermere where viz is low - very low (2 metres in summer, 5 in winter) which can create a challenge for your buddy and self when trying to spot where the lines are. Because of this some of us opt not to use smbs.

Speaking from experience:
Another problem we have is that other water users in yachts and the like (obviously with little experience) suddenly get the urge to go chase after the smb and attempt to pull it up with their grappling hooks and us with it - say no more :eek: For the given circumstance which one is the safer option and bearing in mind that shore cover can see where we are on most occcasions. Life can be difficult in the lakes.

At least there are no more waterskiers using your blob to turn around on. :D

[Paul Renucci]

Hi Andy - you've got me rolling around on the floor at your reply.
I don't mind describing the experience - nice peaceful and relaxing dive followed by an invisible force pulling you violently upwards :eek: . Scary stuff.

I had to slice through the reels lanyard because the pressure on the carabina stopped me from using the "quick?" release. Never saw the reel again :( but at least I'm still here :) . You should have seen my dive buddies face :eek: when he saw me take off vertical - thank god I was fast if you know what I mean.

The shore cover told us what had happened from their vantage point.
As Andy says, at least there ani't no more speed boats in Windermere.
The lake this all happened in was Ullswater (4 years ago).

[Andy Wade]

Hi Andy - you've got me rolling around on the floor at your reply.
I don't mind describing the experience - nice peaceful and relaxing dive followed by an invisible force pulling you violently upwards :eek: . Scary stuff.

I had to slice through the reels lanyard because the pressure on the carabina stopped me from using the "quick?" release. Never saw the reel again :( but at least I'm still here :) . You should have seen my dive buddies face :eek: when he saw me take off vertical - thank god I was fast if you know what I mean.

The shore cover told us what had happened from their vantage point.
As Andy says, at least there ani't no more speed boats in Windermere.
The lake this all happened in was Ullswater (4 years ago).

Yes, I can also laugh about it years after the event, but at the time....:eek:
My experience was similar to yours, except that I was diving a wreck on the N E coast, and it was another dive boat's grapnel hook catching my blob line, they set off with the boat before they had properly landed the hook, how stupid is that? Took my blob and the reel and line with it, never stopped either.
#astards.
Fortunately my wrist lanyard slipped off my hand as the line tensed up, luck was with me that day... well kind of, I too never saw my kit again.